adm roadway design manual

ROADWAY DESIGN MANUAL – Roads and Bridges

TTaabbllee ooff CCoonntteennttss PPaaggee NNoo..

Page -1-

PART 1: ROADWAY DEVELOPMENTSECTION 100: GENERAL INFORMATION

101 PURPOSE 100-1101.01 INTRODUCTION 100-1

102 CONTENTS AND ORGANIZATION 100-1102.01 PART 1: ROADWAY DEVELOPMENT 100-1102.02 PART 2: ROADWAY DESIGN 100-2102.03 PART 3: STRUCTURES AND BRIDGES 100-2

103 TECHNICAL MEMORANDUMS 100-2103.01 GENERAL 100-2103.02 TECHNICAL MEMORANDUMS - GENERAL 100-2103.03 TECHNICAL MEMORANDUMS - SPECIFIC 100-3

104 ROADWAY CLASSIFICATIONS 100-3104.01 ROADWAY SYSTEM 100-3104.02 DESIGN 100-3104.03 CRITERIA FOR DESIGN CLASS DESIGNATION 100-3

105 ROUTE DESIGNATIONS 100-5105.01 INTRODUCTION 100-5105.02 ROUTE NUMBERS 100-5105.03 ADDITIONS, DELETIONS, AND REVISIONS 100-5

SECTION 200: DESIGN CONCEPT DEVELOPMENT201 TRANSPORTATION PLANNING 200-1

201.01 INTRODUCTION 200-1201.02 ROAD SECTION 200-1201.03 TOWN PLANNING 200-1201.04 MAPPING 200-1

201.04.01 General 200-1201.04.02 Topographic Mapping 200-2

201.05 PROJECT LIMITS 200-2201.06 PROJECT IDENTIFICATION AND NUMBERING 200-6201.07 INTERDEPARTMENTAL COORDINATION 200-6

202 ENVIRONMENTAL FACTORS INFLUENCING DESIGN 200-6202.01 INTRODUCTION 200-6202.02 SOCIOECONOMIC/COMMUNITY RESOURCE DATA 200-6

202.02.01 Land Use 200-6202.02.02 Growth Projections 200-7202.02.03 Public Services 200-7202.02.04 Schools 200-7202.02.05 Mosques 200-8202.02.06 Utilities 200-8202.02.07 Security 200-8202.02.08 Commercial Activities 200-9202.02.09 Economics 200-9202.02.10 Local Transportation/Circulation 200-9202.02.11 Parking Requirements 200-9202.02.12 Recreation 200-10202.02.13 Historical Site Identification and Preservation 200-10

202.03 NATURAL/ENVIRONMENTAL RESOURCE DATA 200-10202.03.01 Landscape Preservation 200-10202.03.02 Topography 200-11202.03.03 Water 200-11202.03.04 Wildlife 200-11202.03.05 Air Quality 200-11202.03.06 Noise 200-11



Page -2-

202.03.07 Visual/Aesthetic 200-11202.03.08 Hazardous Materials 200-11

202.04 ENVIRONMENTAL CHECKLIST 200-12203 TECHNICAL INVESTIGATIONS 200-12

203.01 INTRODUCTION 200-12203.02 GEOTECHNICAL ENGINEERING 200-12203.03 TRAFFIC COUNTS 200-12

203.03.01 Introduction 200-12203.03.02 Traffic Projections 200-13203.03.03 Procedures for Traffic Volumes 200-14

203.04 SURVEY CONTROL/FIELD SURVEYS 200-14203.04.01 Introduction 200-14203.04.02 Horizontal Control 200-14203.04.03 Vertical Control 200-14203.04.04 Coordinate System 200-14203.04.05 Field Surveys 200-14

203.5 DRAINAGE SURVEYS 200-15 SECTION 300: DESIGN CONCEPT REPORT

301 CONTENTS 300-1301.01 FORMAT 300-1

302 EXECUTIVE SUMMARY 300-3303 INTRODUCTION 300-3304 TRAFFIC ANALYSIS 300-3305 DESCRIPTION OF ALTERNATIVES 300-3306 DESIGN DATA 300-4307 TYPICAL SECTIONS 300-4308 GEOMETRICS 300-4309 INTERCHANGE/ INTERSECTION CONFIGURATION 300-5310 PARKING STUDY 300-5311 HYDROLOGY AND HYDRAULICS 300-5

311.01 PURPOSE 300-6311.02 PLANNING & PREPARATION OF THE DRAINAGE DESIGN CONCEPTS 300-6

311.02.01 Problem Categories 300-7311.02.02 Flood Plain Encroachment and Risk Evaluation 300-9311.02.03 Data Collection 300-10

311.03 STORM WATER HYDROLOGY 300-14311.04 OPEN CHANNEL HYDRAULICS 300-15311.05 BRIDGE HYDRAULICS 300-16

311.05.01 Bridge Location and Hydraulics Report 300-16311.05.02 Bridge Hydraulics Recommendations Sheet (BHRS) 300-19

311.06 STORMWATER MANAGEMENT USING RETENTION/DETENTION DESIGN 300-20312 SUBSURFACE INVESTIGATIONS 300-21313 BRIDGE TYPE SELECTION 300-21

313.01 BRIDGES OVER WATERWAYS 300-22313.02 WIDENINGS/REHABILITATION 300-22313.03 BRIDGE SELECTION REPORT 300-22

314 UTILITY IMPACT ANALYSIS 300-23315 SOCIOECONOMIC ANALYSIS 300-23316 AGRICULTURE IMPACT 300-23317 PUBLIC FEEDBACK 300-24318 SIGNING AND PAVEMENT MARKINGS 300-24319 LIGHTING CONCEPTS 300-24320 CONSTRUCTION STAGING 300-24321 COST ESTIMATE 300-25322 CONCLUSIONS/RECOMMENDATIONS 300-25



Page -3-

323 APPENDIX 300-25324 DRAWINGS 300-25

PART 2: ROADWAY DESIGNSECTION 100: GENERAL DESIGN CRITERIA

101 DESIGN SPEED 100-1102 DESIGN VEHICLES 100-3103 DESIGN TRAFFIC 100-3

103.01 DESIGN PERIOD 100-3103.02 RELATION TO DESIGN 100-3

104 ROADWAY CAPACITY 100-3104.01 DESIGN CAPACITIES 100-3

104.01.01 Multi-lane Rural Roadway 100-4104.01.02 Two Lane Roadways 100-4104.01.03 Expressways 100-5104.01.04 Expressway Ramps and Weaving Sections 100-5104.01.05 Intersection Capacity 100-5

105 CONTROL OF ACCESS 100-5105.01 GENERAL 100-5105.02 ACCESS CONTROL DESIGN CRITERIA 100-5

105.02.01 Primary Roadways 100-5105.02.02 Secondary Roadways, ADT > 2500 100-6105.02.03 Secondary Roadways, ADT < 2500 100-6

105.03 USE OF FRONTAGE ROADS 100-7105.04 PROTECTION OF ACCESS RIGHTS 100-7

106 DESIGN STANDARD EXCEPTIONS 100-7107 BICYCLE FACILITIES 100-9

107.01 GENERAL 100-9107.02 SPECIAL BICYCLE FACILITIES 100-9107.03 BICYCLE CHARACTERISTICS 100-9107.04 BICYCLES AT INTERSECTIONS 100-9

SECTION 200: GEOMETRIC DESIGN STANDARDS201 SIGHT DISTANCE 200-1

201.01 GENERAL 200-1201.02 PASSING SIGHT DISTANCE 200-1201.03 STOPPING SIGHT DISTANCE 200-1201.04 STOPPING SIGHT DISTANCE AT GRADE CRESTS 200-1201.05 STOPPING SIGHT DISTANCE AT GRADE SAGS 200-3201.06 STOPPING SIGHT DISTANCE ON HORIZONTAL CURVES 200-3201.07 DECISION SIGHT DISTANCE 200-3

202 SUPERELEVATION 200-3202.01 GENERAL 200-3202.02 SUPERELEVATION STANDARDS 200-4202.03 CITY ROAD CONDITIONS 200-4202.04 AXIS OF ROTATION 200-6202.05 SUPERELEVATION TRANSITION 200-6202.06 SUPERELEVATION OF COMPOUND CURVES 200-6

203 HORIZONTAL ALIGNMENT 200-9203.01 GENERAL 200-9203.02 STANDARDS FOR HORIZONTAL CURVATURE 200-9

204 VERTICAL ALIGNMENT 200-10204.01 GENERAL 200-10204.02 VERTICAL ALIGNMENT POSITION WITH RESPECT TO CROSS SECTION 200-10204.03 STANDARDS FOR GRADES 200-10



Page -4-

204.04 VERTICAL CURVES 200-11204.05 LONG SUSTAINED GRADES 200-11204.06 STRUCTURE GRADE LINE 200-11204.07 SEPARATE PROFILE GRADE LINES 200-16

205 COORDINATION OF HORIZONTAL AND VERTICAL ALIGNMENTS 200-16206 PAVEMENT TRANSITIONS 200-16

206.01 GENERAL 200-16206.02 TRANSITIONS FOR MULTILANE ROADWAYS 200-16

207 BRIDGES AND GRADE SEPARATION STRUCTURES 200-18207.01 CLEAR WIDTH 200-18207.02 CROSS SLOPE 200-18207.03 SIDEWALKS 200-18

208 PEDESTRIAN FACILITIES 200-18208.01 SIDEWALKS 200-18208.02 PEDESTRIAN GRADE SEPARATIONS 200-18208.03 PEDESTRIAN UNDERPASSES 200-18

209 CURBS 200-18209.01 GENERAL 200-18209.02 TYPES AND USES 200-19209.03 CURB PARAMETERS 200-19

210 BUS STOPS AND TAXI STOPS 200-19210.01 BUS STOPS 200-19210.02 TAXI STOPS 200-19

211 PARKING 200-20211.01 GENERAL 200-20211.02 PARKING AREAS 200-20211.03 ON ROAD PARKING SPACES 200-20211.04 PARKING LOTS 200-21211.05 PARKING DEMAND/SUPPLY ANALYSIS 200-21

SECTION 300: GEOMETRIC CROSSECTIONS301 TRAVELLED WAY STANDARDS 300-1

301.01 TRAVELLED WAY WIDTH 300-1301.02 TRAVELLED WAY CROSS SLOPES 300-1

302 SHOULDER STANDARDS 300-1302.01 SHOULDER WIDTH STANDARDS 300-1302.02 SHOULDER CROSS SLOPES 300-1

303 SIDE SLOPE STANDARDS 300-1303.01 SIDE SLOPE VALUES 300-2303.02 SLOPE CLEARANCE FROM RIGHT OF WAY 300-2

304 MEDIAN STANDARDS 300-2305 CROSS SECTION ELEMENTS 300-2

305.01 RURAL FREEWAY/EXPRESSWAY CROSS SECTION 300-2305.02 URBAN FREEWAY/EXPRESSWAY CROSS SECTION 300-2305.03 ARTERIAL (MAIN ROAD) CROSS SECTION 300-4305.04 SECTOR ROAD CROSS SECTION 300-5305.05 FRONTAGE ROAD CROSS SECTION 300-5

306 HORIZONTAL AND VERTICAL CLEARANCES 300-5306.01 HORIZONTAL CLEARANCES 300-5306.02 VERTICAL CLEARANCES 300-6306.03 TUNNEL CLEARANCES 300-6

307 CLEAR ZONE CONCEPT 300-6307.01 APPLICATION OF CLEAR ZONE 300-8

307.01.01 Roadside Terrain: Foreslope 300-8307.01.02 Roadside Terrain: Backslope 300-9307.01.03 Roadside Terrain: Cross-slope 300-9



Page -5-

307.01.04 Roadside Terrain: Ditch 300-9308 BARRIERS 300-11

308.01 BARRIER NEED 300-11308.02 ROADSIDE BARRIER TYPES AND FEATURES 300-11308.03 ROADSIDE BARRIER PLACEMENT 300-12

308.03.01 Lateral Placement 300-12308.03.02 Barrier to Hazard Clearances 300-12308.03.03 Effects of Roadside Terrain 300-13308.03.04 Barrier Length Design 300-13

308.04 MEDIAN BARRIERS 300-15308.04.01 Median Barrier Warrants 300-15308.04.02 Median Barrier Types and Features 300-15

308.05 MEDIAN BARRIER PLACEMENT 300-15308.05.01 Median Geometry 300-15308.05.02 Treatment of Fixed Object Hazards 300-16

308.06 END TREATMENTS AND CRASH CUSHIONS 300-16308.06.01 End Treatments 300-16308.06.02 Crash Cushion-Selection Guidelines 300-18308.06.03 Placement Recommendations 300-18

SECTION 400: AT-GRADE INTERSECTIONS401 GENERAL 400-1402 DESIGN CONSIDERATIONS 400-1403 AT GRADE INTERSECTION TYPES 400-1404 CHANNELIZATION 400-2

404.01 PREFERENCE TO MAJOR MOVEMENTS 400-2404.02 AREAS OF CONFLICT 400-2404.03 INTERSECTION ANGLES 400-2404.04 POINTS OF CONFLICT 400-2404.05 SPEED-CHANGE LANES 400-3404.06 TURNING MOVEMENTS 400-3404.07 REFUGE AREAS 400-3404.08 PROHIBITED TURNS 400-3404.09 EFFECTIVE SIGNAL CONTROL 400-3404.10 INSTALLATION OF TRAFFIC CONTROL DEVICES 400-3404.11 GUIDELINES 400-3

405 DESIGN VEHICLES 400-4405.01 OFF TRACKING 400-4405.02 DESIGN VEHICLES 400-4405.03 TURNING TEMPLATES 400-4

406 INTERSECTION DESIGN STANDARDS 400-4406.01 SIGHT DISTANCE 400-4406.02 EFFECT OF SKEW 400-10406.03 EFFECT OF VERTICAL PROFILES 400-13406.04 LEFT-TURN CHANNELIZATION 400-13406.05 RIGHT-TURN CHANNELIZATION 400-14406.06 TRAFFIC ISLANDS 400-14

407 ROUNDABOUT DESIGN 400-15

SECTION 500: INTERCHANGES501 GENERAL 500-1502 INTERCHANGE WARRANTS 500-1503 DESIGN CONSIDERATIONS 500-1504 INTERCHANGE TYPES 500-1

504.01 THREE-LEG INTERCHANGE 500-1504.02 FOUR-LEG INTERCHANGES 500-3



Page -6-

505 INTERCHANGE DESIGN PROCEDURES 500-8506 INTERCHANGE DESIGN STANDARDS 500-8507 RAMP DESIGN STANDARDS 500-9508 ENTRANCE/ EXIT RAMP DESIGN STANDARDS 500-11

508.01 RAMP TERMINAL DESIGN 500-16

SECTION 600: GEOTECHNICAL ENGINEERING601 INTRODUCTION 600-1602 GENERAL 600-1603 GEOTECHNICAL REPORT 600-1604 STRUCTURAL PAVEMENT SECTION DESIGN 600-2

604.01 GENERAL 600-2604.01.01 Pavement Design Methods 600-2604.01.02 Comparison of Design Results 600-4

604.02 PAVEMENT DESIGN METHOD 600-5

SECTION 700: DRAINAGE701 GENERAL 700-1

SECTION 800: UTILITIES801 GENERAL 800-1802 UTILITY PLANNING 800-1803 SERVICE RESERVATIONS 800-2804 UTILITY DESIGN 800-3

804.01 GENERAL 800-3804.02 UTILITY PROTECTION 800-3804.03 UTILITY RELOCATION 800-4804.04 CONTINGENCY DUCTS 800-4804.05 UTILITY LOCATIONS 800-4804.06 NON-DISRUPTIVE ROAD CROSSINGS 800-4

SECTION 900: TRAFFIC ENGINEERING901 TRAFFIC OPERATIONAL ANALYSIS 900-1

901.01 GENERAL 900-1901.02 OPERATIONAL ANALYSIS 900-1

902 SIGNALIZATION 900-1902.01 TRAFFIC SIGNAL DESIGN 900-1902.02 SIGNALS, POLES, AND CONTROLLERS 900-2902.03 DUCTS AND PULLBOXES 900-3902.04 PYLONS 900-3

903 TRAFFIC SURVEILLANCE 900-3904 SIGNING 900-3

904.01 SIGN STRUCTURE INSTALLATIONS 900-4904.01.01 Ground Mounted 900-4904.01.02 Overhead Mounted 900-4

904.02 SIGN SHEETING 900-5904.03 SIGN TYPES 900-5

904.03.01 Regulatory And Warning Signs 900-5904.03.02 Guide Signs 900-5

904.04 FINAL SIGNING PLAN REQUIREMENTS 900-5904.05 ARABIC LETTERING FOR GUIDE SIGNS 900-10

904.05.01 General 900-10904.05.02 The Arabic Alphabet 900-10904.05.03 Use of the Standard Arabic Script 900-10

904.06 GUIDE SIGN DIMENSIONS 900-10



Page -7-

904.06.01 Single Message Guide Signs (Example 900-02) 900-10904.06.02 Multiple Message Guide Signs (Example 900-03) 900-12

904.07 STANDARD ARABIC SCRIPT FOR HIGHWAY SIGNS 1 OF 14 900-15904.08 SIGN LIGHTING 900-29904.09 SIGN LUMINARES 900-29

905 PAVEMENT MARKINGS 900-29905.01 GENERAL 900-29905.02 TYPES OF PAVEMENT MARKINGS 900-29

905.02.01 Lane Markings 900-29905.02.02 Stop Line Markings 900-30905.02.03 Pedestrian Crossing Markings 900-30905.02.04 Channelization Markings 900-30905.02.05 Pavement Edge Markings 900-30905.02.06 Parking Space Markings 900-30905.02.07 Pavement Symbols 900-30

906 MAINTENANCE OF TRAFFIC 900-30906.01 CONSTRUCTION STAGING 900-30906.02 SAFETY MEASURES 900-31906.03 TEMPORARY TRAFFIC SIGNALS 900-31906.04 MAINTENANCE OF TRAFFIC PLANS 900-31

SECTION 1000: LIGHTING1001 ROADWAY LIGHTING 1000-1

1001.01 GENERAL 1000-11001.02 LIGHTING DESIGN CONSIDERATIONS 1000-11001.03 ILLUMINATION REQUIREMENTS 1000-2

1002 PARKING AREA LIGHTING 1000-31002.01 GENERAL 1000-31002.02 ILLUMINATION REQUIREMENTS 1000-31002.03 LANTERN MOUNTING HEIGHT 1000-41002.04 LANTERN SELECTION 1000-4

1003 SIDEWALK LIGHTING 1000-41003.01 GENERAL 1000-41003.02 ILLUMINATION REQUIREMENTS 1000-41003.03 LANTERN MOUNTING HEIGHT 1000-41003.04 LANTERN SELECTION 1000-4

1004 LIGHTING CONTROLS 1000-41004.01 GENERAL 1000-41004.02 LIGHTING CONTROLLER REQUIREMENTS 1000-41004.03 DESIGN STANDARDS AND PROCEDURES 1000-4

1005 POWER DISTRIBUTION 1000-41006 DESIGN AND SUPERVISION RESPONSIBILITIES 1000-5

SECTION 1100: ROADSIDE DEVELOPMENT1101 LANDSCAPING 1100-11102 IRRIGATION 1100-1

1102.01 IRRIGATION DUCTS 1100-11103 FENCING 1100-21104 SLOPE PAVING 1100-21105 SWEET SAND COVERING 1100-21106 STREET FURNITURE 1100-2

1106.01 GENERAL 1100-21106.02 DESIGN 1100-21106.03 BENCHES 1100-2

1106.03.01 Type A bench 1100-21106.03.02 Type B bench 1100-2



Page -8-

1106.03.03 Type C bench 1100-31106.04 BUS SHELTERS 1100-31106.05 TELEPHONE BOOTHS 1100-3

1107 NOISE ABATEMENT 1100-3

PART 3: STRUCTURE DESIGNSECTION 100: DESIGN CRITERIA

101 GENERAL 100-1101.01 PURPOSE 100-1101.02 DEFINITIONS 100-1101.03 BRIDGE TYPES 100-1

102 DESIGN FEATURES 100-2102.01 GENERAL 100-2102.02 DESIGN METHODS 100-2102.03 VERTICAL CLEARANCE AT STRUCTURES 100-2

102.03.01 Highway Traffic Structures 100-2102.03.02 Pedestrian Overpasses 100-2102.03.03 Railroad Overpasses 100-2102.03.04 Tunnels 100-3102.03.05 Sign Structures 100-3102.03.06 Width 100-3

102.04 RAILINGS 100-3102.05 CONCRETE BARRIER TRANSITIONS 100-3102.06 APPROACH SLABS 100-3102.07 ANCHOR SLABS 100-3102.08 DECK DRAINAGE 100-3102.09 WING WALLS 100-4102.10 LIGHTING 100-4102.11 BRIDGE DECK ELEVATIONS 100-4102.12 CONCRETE CRACK CONTROL 100-4102.13 CORROSION PROTECTION 100-4

103 ARCHITECTURAL CONSIDERATIONS 100-4103.01 PROCEDURE 100-4103.02 GENERAL CRITERIA 100-5

SECTION 200: DESIGN LOADS201 LOAD TYPES 200-1

201.01 GENERAL 200-1201.02 DEAD LOADS 200-1201.03 FUTURE WEARING SURFACE 200-1201.04 WEARING SURFACE 200-1201.05 HIGHWAY LOADS 200-1201.06 STRUCTURE LOADINGS 200-1201.07 FRICTION FORCES 200-1201.08 THERMAL FORCES 200-1201.09 STREAM FORCES 200-1201.10 LATERAL EARTH PRESSURE 200-3201.11 DIFFERENTIAL SETTLEMENT 200-3201.12 EARTHQUAKES 200-3

202 DISTRIBUTION OF LOADS 200-4202.01 SUPERIMPOSED DEADLOAD DISTRIBUTION 200-4202.02 CONCRETE BOX GIRDERS 200-4202.03 PRESTRESSED VOIDED SLABS 200-4202.04 PRESTRESSED BOX BEAMS 200-4202.05 LATERAL TENSIONING OF MULTI-BEAM UNITS 200-5



Page -9-

202.06 LIVE LOAD DISTRIBUTION 200-5203 LOAD FACTORS 200-5

SECTION 300: REINFORCED CONCRETE301 GENERAL 300-1

301.01 CONCRETE 300-1301.02 DIAPHRAGMS 300-1301.03 DESIGN METHODS 300-1301.04 REINFORCEMENT 300-1

302 SLAB DESIGN 300-1302.01 SPAN LENGTHS 300-2302.02 SLAB THICKNESS 300-2302.03 PROTECTION AGAINST CORROSION 300-2302.04 DISTRIBUTION METHOD 300-2302.05 RAILING LOADS 300-2

SECTION 400: PRESTRESSED CONCRETE401 DESIGN CRITERIA 400-1

401.01 GENERAL 400-1401.02 ALLOWABLE STRESSES—CONCRETE 400-1401.03 SHEAR 400-1

402 POST TENSIONED BOX GIRDER BRIDGES 400-2402.01 GENERAL 400-2402.02 CONCRETE 400-2402.03 BEARING PADS 400-2402.04 CREEP AND SHRINKAGE 400-2402.05 FLANGE AND WEB THICKNESS - BOX GIRDERS 400-2402.06 DIAPHRAGMS 400-2402.07 DEFLECTIONS 400-2402.08 ALLOWABLE STRESSES - PRESTRESSING STEEL 400-2402.09 ALLOWABLE STRESSES-CONCRETE 400-2402.10 LOSS OF PRESTRESS 400-3402.11 FLEXURAL STRENGTH 400-3402.12 SHEAR 400-3402.13 FLANGE REINFORCEMENT 400-3402.14 METHOD OF ANALYSIS 400-3

403 PRECAST PRESTRESSED CONCRETE 400-4403.01 CONCRETE 400-4403.02 DEFLECTIONS 400-4403.03 ALLOWABLE STRESSES-PRESTRESSING STEEL 400-4403.04 ALLOWABLE STRESSES-CONCRETE 400-5403.05 LOSS OF PRESTRESS 400-5403.06 SHEAR 400-5403.07 METHOD OF ANALYSIS 400-5

404 PRESTRESSED I-GIRDERS 400-5404.01 GENERAL 400-5404.02 CONCRETE 400-5404.03 EFFECTIVE FLANGE WIDTH 400-6404.04 SHEAR 400-6404.05 INTERMEDIATE DIAPHRAGMS 400-6404.06 BEARING PADS 400-6404.07 CREEP FACTOR 400-6404.08 FRAMES AND CONTINUOUS CONSTRUCTION 400-6404.09 DIFFERENTIAL SHRINKAGE 400-7404.10 METHOD OF ANALYSIS 400-7

405 PRESTRESSSED VOIDED SLABS 400-7



Page -10-

405.01 END BLOCKS 400-7405.02 DIAPHRAGMS 400-7405.03 LATERAL TIES 400-7405.04 SHEAR KEYS 400-7405.05 BARRIERS 400-7

406 PRESTRESSED BOX BEAMS 400-7406.01 END BLOCKS 400-7406.02 DIAPHRAGM 400-7406.03 LATERAL TIES 400-7406.04 SHEAR KEYS 400-7

SECTION 500: STRUCTURAL STEEL501 DESIGN CRITERIA 500-1

501.01 GENERAL 500-1501.02 DESIGN METHODS 500-1501.03 MATERIALS 500-1501.04 ALLOWABLE FATIGUE STRESS 500-1501.05 LOAD CYCLES 500-1501.06 CHARPY V-NOTCH IMPACT REQUIREMENTS 500-1

SECTION 600: EXPANSION AND CONTRACTION601 MOVEMENT CRITERIA 600-1

601.01 MOVEMENT RATING 600-1602 DECK JOINTS 600-1

602.01 GENERAL 600-1602.02 COMPRESSION SEALS 600-2602.03 STRIP SEALS 600-2602.04 MODULAR JOINTS 600-2

603 BEARINGS 600-2603.01 GENERAL 600-2603.02 NEOPRENE STRIPS 600-3603.03 ELASTOMERIC BEARING PADS 600-3603.04 STEEL BEARINGS 600-4603.05 SLIDING ELASTOMERIC BEARINGS 600-4603.06 HIGH-LOAD MULTI-ROTATIONAL BEARINGS 600-4

603.06.01 Description 600-4603.06.02 Rotational Requirements 600-5603.06.03 Use 600-5603.06.04 Design Criteria 600-5

603.07 BEARING SCHEDULE 600-7604 RESTRAINING DEVICES 600-7

604.01 GENERAL 600-7604.02 VERTICAL FIXED RESTRAINERS 600-7604.03 VERTICAL EXPANSION RESTRAINERS 600-8604.04 EXTERNAL SHEAR KEYS 600-8604.05 INTERNAL SHEAR KEYS 600-8604.06 KEYED HINGE 600-8

SECTION 700: GEOTECHNICAL701 FOUNDATIONS 700-1

701.01 GENERAL 700-1701.02 SPREAD FOOTINGS 700-1701.03 PILE FOUNDATIONS 700-1701.04 DRIVEN PILES 700-2701.05 BORED PILES 700-2



Page -11-

SECTION 800: RETAINING WALLS801 DESIGN CRITERIA 800-1

801.01 GENERAL 800-1801.02 POLICY 800-1801.03 RESPONSIBILITIES 800-1

801.03.01 Roadway Design Section 800-1801.03.02 Geotechnical Section 800-2801.03.03 Bridge Design Section 800-2

801.04 PROPRIETARY RETAINING WALLS 800-2

SECTION 900: MISCELLANEOUS901 TRAFFIC STRUCTURAL SUPPORTS 900-1

901.01 GENERAL 900-1901.02 WIND SPEED 900-1901.03 ALLOWABLE STRESSES 900-1

902 UTILITIES IN STRUCTURES 900-1902.01 GENERAL 900-1902.02 POLICY 900-2902.03 UTILITY AGENCY RESPONSIBILITY 900-2902.04 BRIDGE GROUP RESPONSIBILITY 900-2

903 FALSEWORK POLICY FOR BRIDGE CONSTRUCTION 900-3903.01 FALSEWORK REQUIREMENTS 900-3903.02 FALSEWORK USE 900-3903.03 FALSEWORK CLEARANCES 900-3

904 CONSTRUCTION JOINT GUIDELINES FOR BRIDGE CONSTRUCTION 900-5904.01 GENERAL 900-5904.02 LONGITUDINAL CONSTRUCTION JOINTS 900-5904.03 PRECAST CONCRETE GIRDER BRIDGES 900-5904.04 STEEL GIRDER BRIDGES 900-6904.05 CAST-IN-PLACE BOX GIRDER BRIDGES 900-6


Part 1 100-1

PART 1ROADWAY DEVELOPMENT

SECTION 100GENERAL INFORMATION

101 PURPOSE

101.01 INTRODUCTION

The Manual is intended to serve as a guide for thedesign of the roads and highways that fall underthe jurisdiction of the Road Section, Abu DhabiMunicipality. The Manual provides a range ofacceptable values for critical dimensions andoutlines parameters that will help designersconform to the expectations of the Road Sectionof the Abu Dhabi Municipality. It is assumedthat the user has the educational and engineeringexperience necessary to properly implement itsprocedures, guidelines and criteria.

It is perceived that this manual will promote thefollowing:

1. All designs will be based on identicalcriteria.

2. Plans will have a consistent,well-organized format which will notvary greatly from project to project.

3. Familiarization of criteria and procedureswill be simplified.

4. The technical review process will beexpedited for both the Road Section andthe Consultant.

5. Cost efficiencies will be realized duringdesign by an early understanding ofprocedures and criteria to be employed.

The manual is presented in loose-leaf form tofacilitate revisions and additions. This manualutilized established analysis techniques and designstandards from recognized technical associationsthat are listed as references in Appendix A.

When the Roadway Design Manual is combinedwith the four companion documents listed below,the standardization of the planning, design andconstruction of roadway projects will be

complete. The companion documents to thismanual are:

z Standard Specifications for Roads andBridge Construction - 1996

z Consultant Procedures Manual - 1997z Roadway Standard Drawings - 1996z Construction Supervision Manual - 1997

Where the Consultant's scope of work and thismanual conflict, the scope of work shall govern.

Revisions and additions to this manual will beissued from time to time as required. This sectioncontains information regarding technicalmemorandums used to submit future revisionsand additions.

Further contained in this section is an overview ofthe layout of the manual content, roadwayclassifications, route designations connectingU.A.E cities and emirates, and streets and placenames as assigned by Abu Dhabi Municipality.

102 CONTENTS ANDORGANIZATION

The scope of the Roadway Design Manual iscomprehensive, and is divided into three parts.The three parts are further divided into sections,each with appropriate sub-sections. The threeparts are:

Part 1 Roadway DevelopmentPart 2 Roadway DesignPart 3 Structures and Bridges

102.01 PART 1: ROADWAYDEVELOPMENT

The purpose of the Roadway Development part isto outline the information and data which must beanalyzed to determine a project’s scope. Thisinformation and analyses are assembled into aDesign Concept Report, which becomes the basisfor the project design.

The Roadway Development part is divided intothree sections. The first section explains theformal organization of this manual and the othertwo sections, the Design Concept Development


Part 1 100-2

and the Design Concept Reports, define theconceptual design of the project.

The Design Concept Section includes subsectionsin Transportation Planning, Socio-economicData, and Technical Investigations. ConceptualDesign must be based upon site specificcommunity considerations that reflect military,utility, environmental features, physical propertiesof the site, and circulation that define the projectdesign. To support the land’s intended use,procurement of the information from departmentswithin the Municipality and outside ofMunicipality’s organization is required.

All the Project-specific data collected forms thebasis for the Design Concept Report, a summaryof the technical analyses and schematic designthat are to be used for plan preparation andconstruction.

102.02 PART 2: ROADWAY DESIGN

The purpose of the Roadway Design part is toidentify the design standards that all roadwayprojects are required to meet. The project designis based on these standards. When used inconjunction with the Standard Specifications forRoad and Bridge Construction, and Abu DhabiRoadway Standard Drawings, the resultingproject plans and specifications for all projectsare completed to the same requirements andformat.

Specifically, the Roadway Design Part providesdetails in geometric design standards for eachcomponent of the roadway project. Theinformation is divided into eleven sections thatinclude General Design Criteria, GeometricStandards, Geometric Cross Sections, At GradeIntersections, Interchanges, GeotechnicalEngineering, Drainage, Utilities, TrafficEngineering, Lighting, and RoadsideDevelopment.

102.03 PART 3: STRUCTURES ANDBRIDGES

The purpose of the Structures and Bridges part isto identify the design details with which allstructures are required to comply. As with the

Roadway Design part, this document is intendedto be used in conjunction with the StandardSpecifications and the Abu Dhabi StandardDrawings for the standardization of details forstructures and bridges.

Uniform design and construction of structures andbridges promotes efficiency of design,construction, and maintenance. This part focuseson features incorporating sound design and cost-effective design practices to meet this goal.

This part consists of nine sections that cover thegeneral aspects of structures and bridge design.Subjects covered include, General DesignCriteria, Design Loads, Reinforced Concrete,Prestressed Concrete, Structural Steel,Expansions and Contractions, Geotech andRetaining Walls. The last section addressesmiscellaneous items such as Traffic Supports,Utilities and the Falsework Policy andRequirements.

103 TECHNICAL MEMORANDUMS

103.01 GENERAL

This manual will be supplemented from time totime with technical memorandums (TM)addressed to the Consultants for the purpose oftransmitting and formalizing appropriate revisionsor additions, to the manual. This manual canonly be revised by the issuance of a TMauthorized and signed by the Chief of RoadSection, Abu Dhabi Municipality or hisdesignated representative. Technicalmemorandums will be developed and issued astwo distinct types, general and specific, and arefurther defined below.

103.02 TECHNICAL MEMORANDUMS- GENERAL

Technical Memorandums - General, deal withissues or information that must be distributed on asystem wide basis to all consultants. They arealso used to provide advance directives withrespect to imminent revision or additions to theRoadway Design Manual. Examples arerevisions or refinements to policies, guidelines orcriteria.


Part 1 100-3

103.03 TECHNICAL MEMORANDUMS- SPECIFIC

Technical Memorandums - Specific, deal withissues or information that is of specific interest toa particular section (design contract), and as suchhave no influence or effect on other designsections.

Examples of such memorandums are:

1. Deviations from the Design ProceduresManual on a project specific basis.

2. Drainage Design Guidelines.3. Lighting Design Guidelines.4. Report Transmittals, etc.

104 ROADWAY CLASSIFICATIONS

104.01 ROADWAY SYSTEM

Roadways within the jurisdiction of Abu DhabiMunicipality are classified into one of threefunctional categories, consistent with theTransportation Master plan:

z Primary Roads Freeways Expressways

z Secondary Roads Arterials Collectors

z Local Roads

The design classes discussed in this section areapplicable to all highway networks in both ruraland urban areas under the jurisdiction of the RoadSection, Abu Dhabi Municipality.

Table 100.01 summarizes the majorcharacteristics of the first tier classifications, i.e.,primary, secondary and local roads.

Table 100.02 is a matrix that differentiates theurban and rural roadway types by their first tierclassifications.

104.02 DESIGN

Roadway design standards are dependent on theclassification of the roadway. The Road Sectionwill determine the classification. The DesignConcept Report summarizes the design criteria tobe utilized in the design.

The roadway classification system is based on ahierarchy of roads. Local roads provide access toadjacent land. Collectors provide a combinationof land access and movement of through traffic.Arterials and expressways provide for movementof through traffic. Arterials and Expresswayshave at-grade or grade-separated intersections.Freeways shall have only grade-separatedcrossings and interchanges.

104.03 CRITERIA FOR DESIGN CLASS DESIGNATION

Table 100.03 defines the characteristics of thesecond-tier classifications, i.e., freeways,expressways, arterials, and collectors as theyrelate to design requirements.


Part 1 100-4

Table 100.01Summary of Functional Characteristics for Roadway Classifications*

Primary Roads Secondary Roads Local Roads

Function Regionaltransportation

Regional transportationand/or service to majorland developments

Local circulation

Service Points Connects multipleregions. Servesinternationalconnections and majormilitary installations.

Connects two regions.Serves internationalconnections, militaryinstallations andseaports not served byPrimary Roads. Mayconnect two PrimaryRoads.

Residential,industrial, andrecreational areasnot served by higherclass.

Population Density Connections to urbanareas of 100,000 ormore.

Connections to urbanareas of 50,000 ormore.

None

Access Access is controlled. May be controlled. Minimal control.

Minimum Level of Service C/D C D

Percent of Total Kilometers 35 35 30

Design Speed 120 kph (urban)140 kph (rural)

60 kph (urban)60-100 kph (rural)

50 kph (urban)60-90 kph (rural)

Weather Related RoadClosures - AllowableFrequency

Once per 100 years. Once per 50 years. Once per 25 years.

Minimum Percent of TruckTraffic (Other Than Pickups)

25 20 30

* See Part 2.0 for further details.


Part 1 100-5

105 ROUTE DESIGNATIONS

105.01 INTRODUCTION

The purpose of route designations is to providethe highway user with a consistent expectation ofthe:

z relative direction (north, south, east west)

z design standards (design speeds, shoulders, etc. resulting from

the highway classification)z origin/destination of the road.

Route designation and numbering facilitate rapidand accurate identification of specific locations inthe event of emergencies, accident reporting andanalysis and in the inventory of roadwayappurtenances, i.e., signs, drainage structures,guardrails, etc. Route assignments are made bythe Municipality and based on the functionalclassification of each roadway.

105.02 ROUTE NUMBERS

Figure 100.01 shows the designated routenumbers between emirates and cities within theU.A.E.

Figure 100.02 shows routes designated betweenexisting primary roads and secondary or localroads in the Abu Dhabi Emirate.

105.03 ADDITIONS, DELETIONS, ANDREVISIONS

From time to time, it may become necessary toassign new route numbers, delete route numbersfor obsolete roads or revise route numbers toreflect changes to road classifications. Users ofthis manual shall advise the Municipality if theyperceive the need for changes to the routenumbering system. Note that all changes of thisnature are subject to the approval of Abu DhabiMunicipality.

Table 100.02Roadway Types by Functional Classification

Roadway Roadway Type for DesignClassification Urban Rural

Primary FreewayExpressway

FreewayExpressway

SecondaryArterial(Main Roads)Frontage Roads

Collector• Major• Minor

LocalSector Road• Primary• Local

Local Access


Part 1 100-6

Table 100.03Characteristics of Urban/Rural Design Classes

Freeways/Expressways

Arterials Collectors Locals

Traffic Service:Urban andRural

Optimum mobility Traffic movementprimaryconsideration

Traffic movementand land access ofequal importance.

Traffic movementsecondaryconsideration

Land Service:Urban andRural

Full control of access −no direct land access

Land accesssecondary inconsideration

Traffic movementand land access ofequal importance.

Land accessprimaryconsideration

Traffic Flow Characteristics:Urban andRural

Free flow Uninterruptedexcept atintersections

Interrupted flow Interrupted flow

Private and Commercial Access:Urban andRural

Not permitted None or limited Permitted Permitted

Connection Type for Public Roads:Urban Grade separations &

interchangesAt-gradeintersections,interchanges,orslip-ramps

At-gradeintersections


Rural Grade separations &interchanges

At-gradeintersections orinterchanges



Connects to:Urban Arterials

ExpresswaysFreeways

ArterialsExpressways

Locals Arterials Locals

Rural ExpresswaysCollectorsFreeways

Locals CollectorsExpressways

Locals Collectors Locals Collectors

Vehicle Type:Urban All types up to 20

percent heavy trucksAll types up to 20percent heavytrucks

All types Passenger &service vehicles

Rural All types; heavy trucksaverage 20%-40%

All types up to40% trucks

All types, up to30% heavy trucksin the 3 mg to 5mg class

Predominantlypassenger cars &light to mediumtrucks: occasionalheavy trucks

ADT (20):Urban Level of Service is C/D 5,000-30,000 1,000-12,000 100-1,000Rural Level of Service is C/D 2,000-15,000 200-4,000 0 to 300

Average Running Speed for Off-Peak Conditions:Urban 80-110 kph 50-80 kph 30-50 kph 30-40 kphRural 80-120 kph 60-110 kph 50-90 kph 45-80 kph


Part 1 100-7

Figure 100.01Route Designations Between U.A.E. Cities and Emirates


Part 1 100-8

Figure 100.02Connections Between Primary and Secondary or Local Roads


Part 1 200-1

SECTION 200DESIGN CONCEPT

DEVELOPMENT

201 TRANSPORTATION PLANNING

201.01 INTRODUCTION

Data collection comprises this phase of the pre-design process. Existing data is collected fromthe Abu Dhabi Municipality, other governmentdepartments, landowners, and field surveys. Thisdata becomes the foundation for project road andbridge design. The Consultant is responsible forall data collection.

201.02 ROAD SECTION

The Road Section is the lead department fromwhich all road and bridge projects are initiatedand approved.

The Consultant shall work with assigned staff todevelop the project scope per the ConsultantProcedures Manual and identify applicable designcriteria from the Roadway Design Manual. TheConsultant is expected to develop the project byproper application of Abu Dhabi Municipalitypolicies and standards.

201.03 TOWN PLANNING

The Town Planning Department is comprised oftwo sections:

Planning Section - The Planning Section isresponsible for the development and maintenanceof the Master Plan and planning layouts. TheMaster Plan is the base document from which theproject’s roadway classifications are assigned.Roadway design standards are identified for eachroadway classification (see Tables 100.01,100.02 and 100.03, in Part 1, Section 100,General Information).

The planning layouts are used to identify theexisting and proposed land use and developmentintensity.

Utilities Section - The Town Planning UtilitiesSection is responsible for the development andapproval of all service reservations.

201.04 MAPPING

201.04.01 General

Current, accurate base mapping is an essentialtool in transportation planning. The specificmapping requirements depend on the length andcomplexity of the project and its location, eitherurban or rural. Aerial mapping is normally themost useful and cost-effective medium for largerprojects. Ground topographical surveys are usedfor smaller projects, especially in urban areas andto supplement aerial mapping at specific locationswhere more detail and accuracy is needed.

Three types of aerial maps are used in theplanning and design phases of roadway andbridge projects:

Uncontrolled Aerial Photography - These mapsare produced directly from the aerial photographsthat normally cover large areas at a reduced scale.The maps are generally used in route locationstudies to define transportation corridors andalternative alignments. The contact prints fromthe aerial photography are assembled to form aphotomosaic of the area under study to reducedistortion.

Controlled Aerial Photography - Prior to theflight, horizontal and vertical ground controlpoints are set and marked in the field. Thesepoints are used to control photomosaic productsthat are significantly more accurate and can beprepared at a specific scale. These maps can beused at larger scales for preliminary engineeringactivities including Design Concept Reports.

Topographic (Aerial) Mapping - These mapsrepresent the state-of-the-art in highway designand consist of topographic maps compiled fromcontrolled aerial photography in a digitizedformat that can be input directly to CADD. Thismapping can be used for both design conceptdevelopment and final design and is limited to thebroad roadway corridor.


Part 1 200-2

The Consultant is responsible for providing basemapping for design concept development.Specific requirements will be identified in theConsultant’s scope of work. Existing aerial andtopographic maps may be available and suitablefor use in consultation with the Department. TheAbu Dhabi Municipality and Town PlanningDepartment maintain a limited library of existingmapping which the Consultant shall review forbackground information.

Mapping scales and contour intervals generallysuitable for the intended purpose are shown inTable 200.01.

201.04.02 Topographic Mapping

Topographic maps for a specific project shall beprepared in accordance with the following:

Survey Control/Field Surveys - Therequirements for surveys are included in Section203.04, Survey Control/Field Survey.

CADD Standards - Mapping features andsymbology will be prepared in accordance withthe latest CADD Standards, supplemented by thestandard symbols shown in Figure 200.01, 200.02and 200.03.

Primary Control Points - All primary controlpoints for mapping which were established duringthe initial field survey will be shown on the mapsin their proper locations and with the appropriatesymbol, identification number and elevation. Atabulation of the primary control points shall alsobe shown in the original survey notebook. Thetabulation will show the identification number,coordinates and elevation of the point.

Supplemental Control Points - All supplementalcontrol points established for controlling aerialphotography will be shown on the maps. Theseinclude wing points, analytically bridged points,and aerial photo centers. See Figure 200.01.

Planimetric Features - Natural and manmadefeatures, spot elevations, topographic features andrelevant political subdivision lines shall be plottedon the maps as shown in Figure 200.02 andFigure 200.03.

Coordinate Grid - Coordinate grid ticks shall beshown on the maps at intervals to suit drawing.

North Arrow - A north arrow shall be placed oneach map sheet. The north arrow shall beoriented so that north points to the top or to theright of the map sheet. Match lines shall also belabeled so that each sheet may be joinedaccurately to adjacent sheets.

Map Index - A sheet index diagram shall beprepared for each mapping project. This diagramshall show the position and relationship of eachsheet to adjacent sheets. A title block is alsorequired and shall be placed on each sheet.

Table 200.01Map Scales and Contour Intervals for

Highway DevelopmentPurpose Scales Interval

(m)Route Location Studies:

Mountainous 1:5000 Max. 5Rolling to Flat 1:5000 2

Preliminary Design (DCR):Rural 1:1250 2Urban 1:1250 2

Rural Design: 1:1250 0.5

Urban Design: 1:500 0.5

Detailed Site Design: 1:100 0.51:250 0.5

201.05 PROJECT LIMITS

The Abu Dhabi Municipality will determine thelimits of the project. Typically, the limits includethe roadway/bridge, medians, sidewalk,parkways, and roadside improvements thatenhance the appearance, maintainability andsafety characteristics of the project. The projectlimits may also be determined by phasedimplementation considerations.


Part 1 200-3

Figure 200.01Standard Mapping Symbols - Boundaries and Monuments


Part 1 200-4

Figure 200.02Standard Mapping Symbols - Natural Planimetric Features


Part 1 200-5

Figure 200.03Standard Mapping Symbols - Manmade Planimetric Symbols


Part 1 200-6

201.06 PROJECT IDENTIFICATIONAND NUMBERING

The Abu Dhabi Municipality Road Section willassign the Title and Number for each individualroadway and bridge project. The Consultant willinclude this information on all drawings, reports,correspondence, calculations and other designdocumentation associated with the subject project.

201.07 INTERDEPARTMENTALCOORDINATION

Throughout the development of the project,coordination with Municipality Sections as wellas other government departments is essential.The Consultant is expected to identify therequirements of the involved governmentdepartments, and insure that the project designaddresses these requirements. Table 200.02 liststhe agency or authority responsible fortransportation related functions.

Table 200.02Municipal Agencies

Function Agency/AuthorityRoad/Bridge

Construction ADM-Road SectionPlanning ADM-Town Planning Dept.Utilities ADM-Town Planning Dept.Parking ADM-Road SectionRight-of-Way ADM-Town Planning Dept.Plantation ADM-Agriculture Section

202 ENVIRONMENTAL FACTORSINFLUENCING DESIGN

202.01 INTRODUCTION

There are a number of important environmentalfactors that influence the design of all roadwayand bridge projects. These factors are bothnatural and man-made and have been divided intotwo major categories; Socioeconomic/Community Resource Data and Natural/Environmental Resource Data. The identificationof these resources enables the project to bedeveloped to avoid and/or minimize impact tothese resources to the greatest extent practicable.

This will contribute significantly to publicacceptance and the ultimate success of a project.The following sections describe the variousenvironmental factors that comprise each of thetwo categories. It is the Consultant’sresponsibility to assess each factor and develop afunctional and compatible design.

202.02 SOCIOECONOMIC/COMMUNITYRESOURCE DATA

The Consultant shall consider each of thefollowing factors as part of the development ofproject design. The goal is to develop afunctional design that accommodates or maintainsthe integrity of each socioeconomic andcommunity resource with minimal disruption. Toassist with the planning involved with thedevelopment of the design, the Consultant shouldmap all resources that are capable of being placedonto a map.

202.02.01 Land Use

The project plans must accommodate existing andfuture land use to the extent possible. TheConsultant is required to provide adequateparking and access to adjacent land uses,commensurate with the type of land use and theroadway classification (see Tables 100.01,100.02 and 100.03, Part 1, Section 100, GeneralInformation). The roadway volumes used todetermine the “level of service” (existing and 20-year projection) must include the trip generationassociated with the adjacent land uses.

In the urban areas, the Town Planning MasterPlan is the primary document used to identify thetypes and locations of designated land uses. Inrural areas, where the land usage is less defined,the Consultant must conduct a field survey of theexisting land uses adjacent to the project. Theaforementioned information, combined with thefield survey data, will then be used to identifypotential improvements to be designed as part ofthe roadway project.

In rural areas, formal information regarding landuse may not be available. In these cases, thecurrent land use is typically agricultural and willremain as agricultural unless there is informationstating otherwise.


Part 1 200-7

202.02.02 Growth Projections

The Abu Dhabi Municipality’s roadways aredesigned to serve the traffic volume anticipatedduring the next 20 years. Presently, historicalrecords of past growth trends do not exist.Therefore, it is important that a reasonablegrowth projection is used to “size” the project.

The growth can be categorized as an increase,decrease or no change. It is anticipated that anincrease will be the most probable scenario in theforeseeable future. The rate of growth can beexpected to increase linearly each year orexponentially (i.e., an order of growth magnitudeeach year).

The growth projection can dramatically affectproject “sizing”. Therefore, the Consultant isexpected to develop a realistic growth projectionwhich takes into consideration variables such as:

• increases in vehicle ownership• land use• population growth rate, i.e. linear or

exponential

In urban areas, growth projections are dependentupon the rate at which the Town Planning MasterPlan is implemented, as well as the proposedtypes of land use. The Consultant is expected toconfer with the Town Planning Department toascertain the rate at which the Town PlanningMaster Plan is to be implemented.

In the rural areas, information regarding growth isless defined. In these cases, it is necessary thatthe Consultant make growth projections. Theseprojections should take into account any dataconcerning growth, including changes in land useadjacent to the roadway. As a starting point, itcan be assumed that the use of land is primarilyagricultural, with an average growth of 1% to 2%per year for a period of 20 years.

The resulting growth projection, along withsupporting data and the rationale used tosubstantiate the project, shall be approved by theTown Planning Section.

202.02.03 Public Services

The development of all road and bridge projectstypically affects many public services. This canresult from encroachment of the improvementproject beyond the existing roadway, sidewalk,and bridge. As such, pre-design coordinationwith public services is required to incorporatedesign approaches and construction phasing thatminimize the project impact.

The Consultant is responsible for identifying allpublic services which may be affected by theroadway/bridge project. In addition, theConsultant is also responsible to compile allrelevant design requirements from the affectedpublic services and incorporate these parametersinto the project design. It is the Consultant’sresponsibility to assure the Abu DhabiMunicipality that the design and constructionphasing meets the approval of the affected publicservice.

Table 200.03 identifies the various PublicServices and the responsible agency/authority foreach.

Table 200.03Public Services

Service Agency/AuthorityRoad/Bridge

Construction ADM-Road SectionAgriculture/Parks ADM-AgriculturePolice Police Directorate/

Traffic Police Dept.Fire Civil Defense Dept.Security Defense Dept./CIDSchools Town Planning/

Ministry of EducationSanitation ADM - Health SectionParking ADM - Road SectionRecreational Town Planning/

AgricultureNavigable Waters Coast GuardMail Service Postal DirectoratePublic Transportation ADM - Public Transport

Section

202.02.04 Schools

Schools are an important national resource. Thedesign shall accommodate and preserve sufficientaccess to all facilities that are affected by projectdesign. Therefore, the Consultant is expected to


Part 1 200-8

adapt the project’s design to accommodate eachschool’s needs.

For each school, there are a number of factorsthat must be considered in the project design.These include:• school bus traffic• crosswalks• school yard fencing• parking• landscaping• noise attenuation (i.e., insulated windows,

soundwalls)• other safety improvement• relocation of affected structures, as necessary• affects on potential school expansion

In the case of new school site development, theTown Planning Master Plan and Town Planningstaff shall be consulted to identify these siteswithin and/or adjacent to the project limits.

As with all other adjacent property improvements,the Consultant is required to provide plans whichcan be used to construct the necessaryimprovements either in conjunction with theroadway/bridge project or as a separate project.This is intended so that construction can beundertaken on the school sites during scheduledschool closures.

202.02.05 Mosques

Mosques are extremely important to the Islamicfaith and cannot be relocated or impacted in anyway. The Consultant shall identify all Mosqueswithin close proximity to a proposed project. Theproject design shall avoid impact to Mosques andshall accommodate and preserve sufficient accessto these sites.

202.02.06 Utilities

Major road and bridge projects typically includeimprovements to all affected utility services. Thisalso includes preparing plans and specificationsfor these improvements. Pre-design activitiesrequire coordination with manyagencies/departments. Final design approval ofthe utility improvements by the utility agencies isalso required. The Utilities Section of the TownPlanning Department is responsible for

establishment and approval of all ServiceReservations.

Table 200.04 lists the ResponsibleAgencies/Authorities for Utilities. A survey ofexisting utilities is required. The purpose of theutilities survey is to determine which utilities can:• remain in place based on field surveys, as-

built plans and other available information:• be protected and/or relocated; and,• affect the horizontal and vertical alignment of

the roadway.

In the case of future or relocated utilities, it maybe necessary to preserve adjacent land for utilityinstallation and relocation. The associated costsfor utility work shall be identified as part of thedesign reflected in the project cost estimate for theDesign Concept Report. Refer to Part 1, Section321, Cost Estimate.

Table 200.04Responsible Agency/Authority for Utilities

Service Agency/ AuthorityWater ADM-WED Water (Water and

Electricity Dept.)Sewer ADM-Sanitary Drainage

Network SectionTelephone ETISILATElectricity ADM-WED Electrical (Waterand

Electricity Department.)Lighting ADM-WED (Water and

Electricity Department)

202.02.07 Security

Nearly every project is affected by some level ofsecurity issue. All embassies, governmentinstallations, palaces, schools, banks and VIPhomes are protected by guards with guardhouses,and associated channeling devices. As a result,many of these facilities interfere with road andbridge projects.

The Consultant is required to minimize therelocation of affected facilities as part of the roadand bridge project. As with all other adjacentproperty improvements, the Consultant is requiredto provide plans which can be used to constructthe necessary improvements either in conjunction


Part 1 200-9

with the roadway/bridge project or as a separateproject. This is intended so that construction canbe undertaken outside of the project right-of-wayat the convenience of the affected property owner.Since each case will vary, the limits ofimprovement, access, facility relocation, parking,etc. requires review by the affected party and theAbu Dhabi Municipality. The Consultant is alsoresponsible to assure the Department that theproposed improvements located outside of theproject right-of-way are agreeable to the affectedproperty owner.

202.02.08 Commercial Activities

The effects of commercial activities on the roadand bridge design shall be taken into account.For example, existing access shall be maintainedas well as accommodating special features of thenon-project site. As a result, coordination withthe Town Planning Department, adjacentlandowners and governmental departments isrequired to lessen the impact of the road/bridgeimprovement project on commercial activities.

202.02.09 Economics

The Consultant shall assess the economicconditions that exist within the project study area,including income and employment characteristics,tax base and property values. The Consultantshall develop a design that seeks to minimizeadverse impacts on these and other economicindicators. This will be done through directcoordination with representatives of theMunicipality.

202.02.10 Local Transportation/Circulation

In order to insure that the project fullyincorporates local transportation/circulationneeds, the Consultant shall address the following:

• Need for Public Transit Stops orTurnouts

• Staging areas for RegionalTransportation Hubs

• Police Enforcement Pads• Pedestrian Walkways and Islands• Special Landscape Areas

202.02.11 Parking Requirements

Roadway and bridge projects typically can affectparking. For example, removal of on-streetparking to accommodate road widening mayresult in the need for off-site parking.

Each roadway and bridge project requires thepreparation of a parking study. The intent of thisanalysis is to establish existing and ultimateparking requirements.

The components of the study include, but are notlimited to:

• calculation and survey to establishexisting parking demand

• future growth of parking demand, as afunction of land development intensity,vehicle ownership/occupancy trends, etc.

• opportunity for mixed parking utilization

Both peak and off-peak parking demands shouldbe included in the analysis.

Table 200.05 identifies the minimum parkinggeneration rates for Central Business Districts(CBD’s). These rates are to be used in theparking analysis. However, the parking analysisshould state the rationale used for proposing ratesother than the stated minimum rates. In no case,shall lower parking generation rates be utilized,unless approved by the Abu Dhabi Municipality.

In rural areas and for areas outside the CBD, anappropriate parking demand shall be establishedon the basis of existing development needs, aswell as review of the demand for other similarfacilities.


Part 1 200-10

Table 200.05Existing and Future Parking Generation Rates (CBD)

Use Period Rate Vehicle OccupancyFactors

Vehicle OwnershipFactors

Residential Existing 1 space/1000 SF .80 .67Future 1 space/1000 SF .85 .80

Commercial Existing 1 space/500 SF .85 1.00Future 1 space/500 SF .90 1.00

202.02.12 Recreation

A variety of recreation and leisure activities areavailable to residents of Abu Dhabi. These caninclude ball fields, beach access, clubs, golfcourses, movie theaters and entertainmentcomplexes.

As part of the pre-design activities, theConsultant is required to identify the potentialeffects on adjacent recreational facilities. TheConsultant is required to minimize the relocationof affected facilities as part of the road and bridgeproject. As with all other adjacent propertyimprovements, the Consultant is required toprovide plans which can be used to construct thenecessary improvements either in conjunctionwith the roadway/bridge project or as a separateproject.

202.02.13 Historical Site Identification andPreservation

The government recognizes the importance of allhistorical sites and structures that relate to AbuDhabi’s cultural development. The goal of thegovernment is to identify these sites as they arediscovered, and, where appropriate, preserve thesites.

During the pre-design process, informationregarding historical sites shall be compiled fromavailable sources as well as conducting an initialsite survey. The Consultant shall also meet withrepresentatives of the Municipality to determinethe significance of the site and presentrecommendations as to appropriate preservationprocedures.

202.03 NATURAL/ENVIRONMENTALRESOURCE DATA

Natural/Environmental resources within a projectstudy area shall be assessed and consideredduring development of the project design. Thegoal is to develop a functional design that avoidsor minimizes impact to the natural environment tothe greatest extent practicable. To facilitate theplanning process involved in the development ofthe design, the Consultant should map allresources capable of being placed on a map.

202.03.01 Landscape Preservation

Preservation of existing landscaping, agriculturalareas and trees adjacent to proposed roadwayprojects is extremely important.

Pre-design activities include a survey of existingvegetation as part of the design survey stage. Theresults of this survey are to be discussed with theAbu Dhabi Municipality and the AgricultureSection. Road/bridge improvements includingutility locations shall be designed to minimizeremoval of vegetation.

The landscaping survey includes the identificationof the number, size, type, condition, and locationof all trees, shrubs, succulents, flowers, andgrasses. The presence of any vegetation that isspecifically protected by decree, or that isconsidered rare, threatened, or endangered, shallalso be identified during the survey. The surveyinformation should then be presented on a scaledplot plan. The scale of each sheet should beadequate to clearly convey the informationcontained on it. Each sheet should contain alegend, which lists the botanical name of theplant, and its common name. For trees, the sizeof the tree shall also be listed.


Part 1 200-11

All urban area projects include landscaping in themedians and other designated areas within theproject limits. The landscaping design isnormally undertaken by the Agriculture Section.However, the Consultant’s design, shall ensurethe following are provided as part of the project,if so required:

• Irrigation Service• Sidewalks• Walls• Fences

Water for irrigation is reclaimed water from thesewage treatment plant, therefore all largedistribution lines require design input from, aswell as approval by, the Sanitary DrainageNetwork Section.

The Agriculture Section will assumeresponsibility for plantings and other specialfeatures.

Maintenance and operation of the irrigationsystems are the responsibility of the AgriculturalSection.

202.03.02 Topography

Topographic data is important to the developmentof the Design Concept. Roadway profiles,horizontal alignment, and drainage, are directlyaffected by topography, which, in turn, affect theproject cost. As discussed in Section 201.04,Mapping, the Consultant is expected to reviewexisting maps. In addition, new surveys shall berequired to establish the topography for theproject.

202.03.03 Water

The Consultant shall identify and determine theimportance of all freshwater and saltwaterfeatures within the study area. Aquifers andwells, especially those that supply drinking water,shall also be identified within project limits. Indeveloping the design, the Consultant shall avoidimpacts to water resources to the greatest extentpossible. If avoidance is not an option, theConsultant shall develop a design that minimizesimpact to water resources.

202.03.04 Wildlife

The Consultant shall describe any existingwildlife habitat within the project study area. TheConsultant is responsible for identifying the typesof wildlife species, if any, that are likely to utilizethe habitat. The Consultant’s design shall avoid,where possible, those habitat areas that supportrare, threatened or endangered wildlife species.

202.03.05 Air Quality

The Consultant shall assess a project’s affect onexisting air quality to determine whether or not itwill result in significant deterioration due toincreased air emissions.

202.03.06 Noise

The Consultant shall assess a proposed project’saffect on ambient noise levels to determinewhether or not it will result in a significantdeterioration from the existing condition. Noisesensitive receptors, such as Mosques, schools andresidential dwellings, shall be identified within theproject limits. The Consultant shall strive todevelop a design that will have the least increasein noise levels to these receptors.

202.03.07 Visual/Aesthetic

The Consultant shall assess the existing visualand aesthetic appearance of the project studyarea. In developing the design, the Consultantshould consider the effect that the project willhave on the visual and aesthetic environment uponbuild-out. Views from the project of thesurrounding environment as well as views of theproject from adjacent vantage points shall beconsidered. The objective of the design is todevelop a project that compliments rather thancontrasts the existing visual and aestheticcharacter of the area.

202.03.08 Hazardous Materials

The Consultant shall conduct a survey to identifythe actual presence of or likelihood of hazardousmaterial sites within the project study area.Ideally, the project design should be developed toavoid impacting such hazardous sites. This willreduce the health and safety risk and overall


Part 1 200-12

project cost. If a hazardous materials site cannotbe avoided, the Consultant shall take appropriatesteps to remediate the hazardous site prior toconstruction in order to reduce the potentialhealth/safety risk.

202.04 ENVIRONMENTALCHECKLIST

All of the environmental factors described inSections 202.02 and 202.03 are included in theEnvironmental Checklist located at the end of thissection. Where appropriate to this project, theConsultant shall use the Environmental Checklistas an initial tool to identify those environmentalfactors that may influence the design ofalternatives

The checklist is designed as a question andanswer exercise that will aid in the comparison ofproject alternatives. A response of “No” to aspecific question means the environmental factorin question is not applicable to the project. Aresponse of “Yes” or “Maybe” indicates to theConsultant that the environmental resource existsand may be affected by the proposed project. Inthis case, the resource should be assessed furtherduring the development of alternative designs todetermine the exact nature and extent of impactthat will be incurred on that resource. Theobjective is to design a project alternative that hasthe least amount of adverse impact to theenvironmental factors on the checklist. Analternative design that yields all “No” answers onthe Environmental Checklist is considered to bethe ideal design. However, this ideal situation isseldom achieved as there is always some level ofimpact to the listed environmental considerations.

203 TECHNICAL INVESTIGATIONS

203.01 INTRODUCTION

All roadway and bridge projects require technicalinvestigations, to establish the basic buildingblocks of the design. These technicalinvestigations are initiated in the data collectionphase and continue through the development ofthe Design Concept Report. This subsectionidentifies the initial activities associated withthese investigations. The basic technicalinvestigations include:

• Geotechnical• Traffic Data Collection• Survey Control/Field Surveys• Drainage Surveys

203.02 GEOTECHNICALENGINEERING

The objective of highway geotechnical workshould be to seek, interpret, and evaluatesubsurface and surface data in order to predict thebehavior of the soils and materials along, andadjacent to, the alignment. The resultinginformation is to be presented in a technical reportto be used in the project design.

Data collection includes research of existinggeotechnical reports which were prepared forother projects in the geographic area as well asfield reviews and preliminary testing. For reviewof existing geotechnical reports, the Abu DhabiMunicipality Road Section as well as otherMunicipality and Government agencies should becontacted. The existing data will be used todefine the number of additional soil borings andthe testing requirements for the boring program asdescribed in Part 1, Section 300, Design ConceptReport and Part 2, Section 600, GeotechnicalEngineering. The Consultant shall obtainapproval from the Road Section, Traffic Policeand any other concerned agencies prior tocommencing geotechnical investigation.

203.03 TRAFFIC COUNTS

203.03.01 Introduction

Traffic counts are basic to all phases of highwaydevelopment and operation. An importantcomponent of traffic counts is existing and futuretraffic volumes. Traffic volumes are needed forhighway planning, project cost-benefitcomparisons, priority determinations, analyzing,monitoring and controlling traffic movement onthe highways, traffic accident surveillance,research purposes, highway maintenance, publicinformation, highway legislation and for manyother purposes. However, it should be noted thatthe traffic data collection and projectiontechniques described herein are specificallyintended for providing traffic volume datarequired for roadway and bridge design. It is the


Part 1 200-13

goal of the Abu Dhabi Municipality to establish apermanent automated traffic data collectionsystem for the Municipality. However, until thissystem is fully developed and implemented, thespecific procedures outlined in this section shallbe followed in the collection of traffic data forroadway and bridge projects.

The procedures which follow establish theminimum requirements; however, this does notpreclude the Engineer from using moresophisticated procedures if available.

203.03.02 Traffic Projections

The Abu Dhabi Municipality’s roadways aredesigned to serve the traffic volume anticipatedduring the next 20 years. Therefore, the existingAverage Daily Traffic (ADT) must be projectedover a 20-year time frame. For the 20-year travelforecast, variables such as an increase in autoownership and vehicle registration, population,employment, and residential/ commercial/industrial land uses which strongly influence thefuture traffic volume shall be taken intoconsideration. Presently, a long historical recordof past growth trends does not exist. The AbuDhabi Municipality will use the transportationmodeling software for the City of Abu Dhabi.This model shall be the primary source forprojected traffic volumes over different timeframes. The projected traffic volumes of thistransportation modeling software will be based onchanges in socioeconomic data for the concernedtime period.

In case the transportation modeling software isunavailable, then the following formulas shall beused to determine the ADT for a 20-year timeframe ADT (20). The Engineer is required to thecollect data to determine the current ADT. Inaddition, the Engineer must provide his rationalefor the estimated traffic growth anticipated for thenext 20 years by considering all previouslyacquired data regarding all activity growth in theproximity of the highway improvement.

The following formulas may be applied underassumptions of increasing, decreasing, or equalpercentages of traffic growth over the 20-yearprojection. Formula A shall be used when theEngineer judges that the traffic volume over the

next 20 years will increase exponentially.Formula B shall be used when the Engineerjudges that the traffic volume will increaselinearly.

Formula A:ADT (20) = ADT Present × Growth Factor (GF)

Where GF = 1 +Annual % Traffic Growth 20

100

Formula B:ADT (20) = ADT present +

Annual % Traffic Growth × ADT Present × 20100

Examples:The following is an example of the use of the twoformulas when the annual percent of trafficgrowth is anticipated to be 10 percent and theADT at present is 4,000.

Formula A:ADT (20) = 4,000 × 1 + 10 20

100= (4,000) × (6.73)= 26,920

Formula B:ADT (20) = 4,000 + 10 × 4,000 × 20

100= 4,000 + 8,000= 12,000

The following is an example of the use of the twoformulas when the annual percent of trafficgrowth is anticipated to be 15 percent over thefirst 5-year period and 10 percent over the last15-year period. The ADT present equals 4,000.

Formula A:ADT (20) = 4,000 × 1 + 15 5 + 1 + 10 15

100 100

= 4,000 [(1.15) 5 + (1.10)15]= 4,000 [(2.01) + (4.18)]= 24,760


Part 1 200-14

Formula B:ADT(20) = 4,000+ 15×4,000 ×5 + 10×4000 ×15

100 100

= 4,000 +3,000 + 6,000= 13,000

203.03.03 Procedures for Traffic Volumes

Table 200.06 specifies the minimum proceduresthat shall be met when traffic studies areconducted to identify the present ADT.Collection of traffic volumes for three functionalclasses of highways (Primary, Secondary, andLocal) and five types of improvements (up-grading existing Primary or Secondary Roads;new Primary or Secondary Road on newalignment/location; upgrading existingintersection/interchange on Primary or SecondaryRoads; new intersection/interchange on existingPrimary or Secondary Roads; and new LocalStreets are considered.

203.04 SURVEY CONTROL/FIELDSURVEYS

203.04.01 Introduction

Each project requires initial field surveys toestablish baseline topographic information forproject scoping and design. Setting horizontaland vertical control is of great importance inmapping. Relative position in the horizontalplane is maintained by horizontal control.Horizontal control consists of a series of pointsaccurately fixed in position by distance anddirection in the horizontal plane.

For most topographic surveying, traverses furnishsatisfactory control. For strip maps, the opentraverse is used. The open traverse can be tied tofixed points at each end. For area maps, theclosed traverse is used. The closed traverse canbe closed to form a net which is accurate to thedegree required.

Relative position in the vertical plane can bemaintained by a series of benchmarks in the maparea. These benchmarks are referred to a knowndatum, usually mean sea level.

203.04.02 Horizontal Control

The current inventory of horizontal control pointsestablished in the vicinity of the project will needto be investigated. The Abu Dhabi Municipalityand Town Planning Department should beconsulted on the order of accuracy and status ofexisting primary and secondary control points.

The need for setting new horizontal control pointswill be ascertained from the existing data. Adiscussion of surveying methods and proceduresused to establish new horizontal control points isbeyond the scope of this manual and will becovered in a companion Technical Manual on thesubject of surveying and mapping.

203.04.03 Vertical Control

There are several vertical datum currently beingused for construction in Abu Dhabi. Table200.07 summarizes the most common verticaldatum and the relationship between them. Inaddition, some Sewerage Projects Committeeprojects use their own datum, in which + 100.00meters equals 0.00 meters, New Abu DhabiDatum. All design work will be referred to theNew Abu Dhabi Datum.

203.04.04 Coordinate System

A Coordinate System has been established byAbu Dhabi Municipality Town PlanningDepartment. This Coordinate System shall beused for all surveys.

203.04.05 Field Surveys

Field Surveys will be required on nearly everyproject to supplement the aerial topography,record underground utility or drainage features,reflect new existing features, provide cross-sections and existing pavement elevations at thelimits of improvement, obtain building floorelevations and other related information neededfor preliminary and final design.

Once the horizontal alignment, includingapplicable alternative alignments, has beenestablished, the roadway centerline will be staked


Part 1 200-15

in the field to enable close examination of theroadway location by Department representativesand Consultants staff. The staking interval anddefinition of the project geometrics required willbe determined on a project specific basis inconsultation with the MunicipalityRepresentative.

A detailed survey of the existing greeneryimpacted by the project will be required. Thesurvey will record the location, size and limits ofall trees shrubs and flower beds within the limitsof improvement. Photographs should be taken tosupplement the data. This information will berecorded on drawings and used to investigatealignment adjustments or alternatives that willminimize the removal of greenery.

203.05 DRAINAGE SURVEYS

The Consultant is responsible for acomprehensive survey of drainage facilities andconditions and data collection during the pre-design activities. The data collection consists ofthree activities:

• field review of existing drainage facilities andidentification of flood plains within theproject’s “zone of influence”

• field testing including particle size analysis,scour, etc.

• review of existing drainage master plans(urban areas), hydrologic studies/datacollection (urban and rural areas), and otherpertinent studies

The review of the existing drainage facilitiesshould include:

• pump stations• outfalls• reinforced concrete box structures• channels• ditches• large diameter pipes• pumps, etc.

In absence of drainage master plans or otherpertinent studies to establish area hydrology, theConsultant is responsible to develop/collecthydrologic data. This data is to include:

• rainfall measurement (volume and time) at asuitable collection site, such as the airport

• measurement of area run-off• miscellaneous basic data such as soil type,

land use, aerial photographs, infiltration,evaporation, solar radiation andoceanography

Note that sources for miscellaneous data arescattered. The Consultant must rely upon thecollective experience of design in other similarareas to compile this information.


Part 1 200-16

Table 200.06Procedures for Traffic Studies

EXISTING ROADSPrimary orSecondary Roads

24-hour counts for 7 continuous days for each of four yearly periods:• March, April, May• June, July, August• September, October, November• December, January, February

24-hour manual traffic counts for trucks classified by axle for any three days from the following four days:• Sunday• Monday• Tuesday• Wednesday

Intersections Afternoon (or morning) and evening intersection peak hour counts summarized in 15-minute increments by direction (left turn, right turnand through movements). Counts taken on Sunday or Wednesday, Monday and Tuesday. Hourly summary of same includes separate totalsfor:Passenger vehicles, vans, pick-up trucksBusesTrucks by axle count

Local Streets 12-hour manual counts taken from 6 a.m. to 6 p.m. on Sunday, (or Wednesday), Monday and Tuesday. Total hourly volumes shall berecorded.Convert to 24-hour ADT by multiplying the 12-hour volume by 2. This will provide a conservative estimate of the 24-hour ADT. If moreaccurate volumes are required a 24-hour count should be made.

NEW ROADPrimary andSecondary Roads

Determine/analyze the design ADT for new road using area demographics and travel patterns, determine the redistribution of existing trafficvolumes and traffic volumes generated by new development that will use the new road(s).Conduct Roadside Interview “Origin Destination Surveys” to estimate the directional distribution of traffic.

Local Streets 12-hour manual counts taken from 6 a.m. to 6 p.m. on Sunday or Wednesday, Monday and Tuesday. Total hourly volumes shall be recorded.Convert to 24-hour ADT by multiplying the 12-hour volume by 2. This will provide a conservative estimate of the 24-hour ADT. If moreaccurate volumes are required a 24-hour count should be made.

FOR ALL TRAFFIC COUNTS1. Counts shall not be taken on special holidays or during events which occur once per year.2. Counters shall be placed at points of obvious traffic volume changes3. Manual counts shall be taken at the same place(s) as machine counts. Manual counts shall be used to verify machine counts.4. Manual and machine counts shall be performed for each direction.


Part 1 200-17

Table 200.07Summary of Datums Used In Abu Dhabi

Reference Level Admiralty Chart

Datums

Existing

Admiralty Chart

Datums

Corrected

Abu Dhabi Datums

Old

Abu Dhabi Datums

New

Sauti Datums

Meters Feet Meters Feet Meters Feet Meters Feet Meters Feet

Bench Mark on Plinth of ADPC

Building

3.20 10.50 3.50 11.48 2.15 7.05 2.20 7.22 1.90 6.23

Mean Higher High Water at

Springs near Solstices

1.89 6.20 2.19 7.18 0.84 2.76 0.89 2.92 0.59 1.94

Mean Higher High Water 1.56 5.12 1.86 6.10 0.51 1.67 0.56 1.84 0.26 0.85

Sauti Datums 1.30 4.27 1.60 5.25 0.25 0.82 0.30 0.98 0.00 0.00

Mean Lower High Water 1.19 3.90 1.49 4.89 0.14 0.46 0.19 0.62 -0.11 -0.36

Mean Sea Level 0.95 3.12 1.25 4.10 -0.10 -0.33 -0.05 -0.16 -0.35 -1.15

Abu Dhabi Old Datums 1.05 3.44 1.35 4.43 0.00 0.00 0.05 0.16 -0.25 -0.82

Abu Dhabi New Datums 1.00 3.28 1.30 4.26 -0.05 -0.16 0.00 0.00 -0.30 -0.98

Mean Higher Low Water 0.80 2.62 1.10 3.61 -0.25 -0.82 -0.20 -0.66 -0.50 -1.64

Mean Lower Low Water 0.25 0.82 0.55 1.80 -0.80 -2.62 -0.75 -2.46 -1.05 -3.44

Admiralty Chart Datums Existing 0.00 0.00 0.30 0.98 -1.05 -3.44 -1.00 -3.28 -1.30 -4.27

Mean Lower Low Water at

Spring Near Solstices

-0.18 -0.59 0.12 0.39 -1.23 -4.04 -1.18 -3.87 -1.48 -4.86

Admiralty Chart Datums

Corrected

-0.30 -0.98 0.00 0.00 -1.35 -4.43 -1.30 -4.27 -1.60 -5.25


Part 1 200-18

ENVIRONMENTAL CHECKLIST

Project: Date:

Page 1 of 4 Yes No Maybe

1 Water: Will the pr oposal result in:

Changes in currents, or the course of direction of water movements,in either marine or fresh waters?

Changes in absorption rates, drainage patterns, or the rate andamount of surface water runoff?

Alterations to the course or flow of flood waters?

Change in the amount of surface water in any water body?

Discharge into surface waters, or any alteration of surface waterquality, including but not limited to temperature, dissolved oxygenor turbidity?

Alteration of the direction or rate of flow of ground waters?

Change in the quantity of ground waters, either through directadditions or withdrawals, or through interception of an aquifer bycuts or excavations?

Deterioration in ground water quality, either through direct injection,or through the seepage of leachate, phosphates, detergents,waterborne viruses or bacteria, or other substances into the groundwaters?

Reduction in the amount of water otherwise available for publicwater supplies?

2 Landform: Will the pr oposal result in:

Unstable earth conditions or changes in geologic substructures?

Disruptions, displacement, compaction or overcovering of the soil?

Change in topography or ground surface relief features?

The destruction, covering or modification of any unique geologic orphysical features?

Any increase in wind or water erosion of soils, either on or off thesite?

Changes in deposition or erosion of beach sands, or changes insiltation, deposition or erosion that may modify the bed of theocean, bay, or inlet?

Changes in deposition or erosion or changes in siltation, depositionor erosion that may modify the channel of a wadi or stream, or thebed of a lake?

Placing fill below the ordinary high water mark of wadis andstreams?

Cut or fill placement through swamps, marshes, bogs, and othersimilar areas that are frequently inundated or saturated by groundwater?


Part 1 200-19


3 Vegetation: Will the pr oposal result in:

Change in the diversity of species, or numbers of any species offlora (including trees, shrubs, grasses, crops, microflora, andaquatic plants)?

Reduction of the numbers of any unique, rare, or endangeredspecies of flora?

Introduction of new species of flora into an area, or a barrier to thenormal replenishment of existing species?

4 Wildlife: Will the pr oposal result in:

Changes in the diversity of species, or numbers of any species offauna (birds, land animals including reptiles, fish and shellfish,benthic organisms, insects, or microfauna)?

Reduction of the numbers of any unique, rare, or endangeredspecies of fauna?

Introduction of new species of fauna into an area, or result in abarrier to the migration or movement of fauna?

Deterioration of existing fish or wildlife habitat?

5 Agricultural Lands: Will the pr oposal result in:

Reduction in the quality or quantity of usable farm land?

Reduction in the quality or quantity of usable grazing land?

6 Natural Resources: Will the pr oposal result in:

Increase in the rate of use of any natural resources?

Depletion of any nonrenewable natural resource?

7 Economics: W ill the pr oposal affect local employment,taxes, property values, etc.?

8 Public Services: Will the pr oposal have an effect upon, orresult in a need for new or altered servicesin any of the following areas?

Mosques?

Cemeteries?

Fire protection?

Police protection?

Schools?

Parks or other recreational facilities?

Maintenance of public facilities, including roads?

Health Services?

Other Services?


Part 1 200-20


9 Antiquities/Historical: Will the pr oposal result in analteration of a significant archaeological orhistorical site, structure, object, or building?

10 Air Quality: Will the pr oposal result in:

Increased air emissions or deterioration of ambient air quality?

The creation of objectionable odors?

11 Noise: Will the pr oposal increase existing noise levels?

12 Light & Glare: Will the pr oposal produce new light orglare?

13 Land Use:Will the pr oposal result in the alteration of thepresent or planned land use of an area?

14 Hazardous Conditions: Does the proposal involve a risk ofan explosion or the release of hazardoussubstances (including, but not limited to, oil,pesticides, chemicals or radiation) in the eventof an accident or hazar dous condition?

15 Population: W ill the pr oposal:

Alter the location, distribution, density, or growth of an area?

Affect racial or ethnic groups including minority, elderly, or lowincome?

Split neighborhoods, or separate residences from commercialfacilities?

16 Housing: Will the pr oposal:

Affect existing housing (including, but not limited to, rural or urbanresidences and business or commercial buildings)?

Create a demand for additional housing?

17 Transportation/Circulation: Will the pr oposal result in:

Generation of additional vehicular movement?

Generation of additional movement of bicyclists or pedestrians?

Impact on existing parking facilities, or demand for new parking?

Impact upon existing transportation systems?

Alterations to present patterns of circulation or migration of peopleand domestic animals?

Alterations to waterborne, rail, or air traffic?

Increase in traffic hazards to motor vehicles, bicyclists, orpedestrians?


Part 1 200-21

Page 4 of 4 Yes No Maybe18 Energy: Will the proposal result in:Use of substantial amounts of fuel or energy?

Require the development of new sources of energy?

19 Utilities: Will the pr oposal result in a need for new systems,or alterations to the following utilities:

Power or natural gas?

Communications systems?

Water?

Sewer or septic tanks?

Storm water drainage?

Solid waste collection and disposal?

20 Human Health: Will the pr oposal result in the creation ofany health hazard or potential healthhazard?

21 Aesthetics: Will the pr oposal result in:

The obstruction of any scenic vista or view open to the public?

The creation of aesthetically offensive site open to the public view?

22 Recreation: Will the pr oposal impact upon the quality orquantity of existing recreationalopportunities?

23 Severance: Will the pr oposal disrupt the cohesive natureof the community it resides in?

Will public services be severed from a particular physiographicsegment of the community or a particular population?

Will emergency service routes be disrupted by the proposal? Will aparticular segment of the community be without service or sufferfrom longer response times due to rerouting of emergencyassistance?


Part 1 300-1

SECTION 300DESIGN CONCEPT REPORT

301 CONTENTS

The Abu Dhabi Municipality Road Sectionrequires the preparation and approval of a DesignConcept Report (DCR) prior to commencing finalproject design. The report is to be prepared underthe direction of an experienced engineerdesignated by the Municipality. Part 1, Section200, Design Concept Development, includes adiscussion of the background information anddata collection activities necessary to develop thedesign concept. Part 1, Section 300, DesignConcept Report, contains a discussion of thespecific requirements and content of a DCR.

The role of a DCR is to summarize the needs,alternatives, costs, and overall impacts of theproposed roadway or bridge project. The scopeof the project is defined and the design criteriaidentified. The DCR is the project scopingdocument and the basis for selecting the projectdesign. The basic roadway configurations shownin the DCR will be carried forward to the finaldesign phase.

DCRTable of Contents

• Executive Summary• Introduction• Traffic Analysis• Description of Alternatives• Design Data• Typical Sections• Geometrics• Interchange/Intersection Configurations• Parking Study• Hydrology and Hydraulics• Subsurface Investigations• Bridge Type Selection• Utility Impact Analysis• Socioeconomic Analysis• Agriculture Impact• Public Feedback• Signing and Pavement Markings• Lighting• Construction Staging• Cost Estimate• Conclusion/Recommendations• Drawings, Plans, Profiles, Typical Sections and

Architectural Features

The preliminary engineering activities associatedwith the DCR involve preparation of numeroustechnical studies and reports, many of which areinitiated in the data collection phase as describedin Part 1, Section 200, Design ConceptDevelopment. These are prepared as stand alonedocuments and are included as an Appendices tothe DCR. The DCR will summarize the results ofthese individual reports under the respective topicincluded in the DCR Table of Contents (See textbox). Furthermore, the discussion under eachtopic will address interdisciplinary relationshipsnecessary to coordinate all technical aspects ofthe design concept. The sections that followprovide guidance for the development of thetechnical studies and requirements forpresentation of the material in the DCR.

301.01 FORMAT

The DCR will prepare and packaged as follows:

• DCR (Volume I) - Written portion of thereport bound separately in A4 size.

• DCR (Volume II) - Drawings that accompanythe report bound separately in A3 size.

• DCR (Appendices) -Technical Memorandums, Studies andReports bound in A4 size. For smallerprojects the documents should be boundtogether. Larger projects may requireseparate packaging of the reports, titled asAppendix A, Appendix B, etc.

Each document will include the followinginformation on the cover:

• Municipality of Abu Dhabi, Road Section• Design Concept Report• Volume No. or Appendix No.• Project Name and Route No.• Project Number• Vicinity Map Schematic with Project Termini

noted• Consultant Identification• See Figure 300.01 to be used as the standardcover sheet for the DCR.


Part 1 300-2

Figure 300.01Standard Design Concept Report

Cover Sheet

Location / Desi gn Conce pt Stud y

Project Location

Final Report

Project No.

Prepared for

Abu Dhabi Municipality

Prepared by

De Leuw Cather & Co.3875 N. 44th Street, Suite 250Phoenix, AZ 85018

Preparer’sLogo

ClientLogo

15 May 1997


Part 1 300-3

302 EXECUTIVE SUMMARY

The Executive Summary is a short (2-4 pages)recapitulation of the DCR document. TheSummary should address the following keytopics:

• Purpose and Need of the Project• Alternatives Evaluated• Recommended Design Concept• Major or Controversial Issues• Estimated Cost• Conclusion

It is not necessary to address every aspect ortechnical consideration that is discussed in themain body of the report. The summary shouldfocus on items presented in the report that are ofcritical interest to the Municipality such as anaccurate concise description of the recommendeddesign concept and the estimated cost. It shouldbe clearly stated how the recommended designresponds to the purpose and need of the project.Both the major benefits (i.e. improve trafficcirculation, improve intersection safety) and theadverse impacts (i.e. displacement of coastalvegetation) should be summarized.

303 INTRODUCTION

The introduction is to prepare the reader for thesubject matter that will follow in the body of thereport. It should only be a few paragraphs inlength and should provide a brief description ofthe project as well as the reason for preparing theDesign Concept Report. The project descriptionshould be very general and should identify theproject’s location, the agency/municipality incharge of its implementation, and the source offunding that will be used for its design andconstruction. A statement can also be includedthat identifies how the project fits into the overalltransportation infrastructure of the area.

304 TRAFFIC ANALYSIS

The collection of traffic data and the trafficprojection procedures are discussed in Part 1,Section 203.03, Traffic Counts. The data will beused to analyze and shape the various alternativesand geometrics. This is an iterative process thatresults in identification of the number of through

lanes, auxiliary lanes, turning lane requirementsincluding storage lengths, signal warrants, level ofservice and capacity. Schematic diagrams of theroadway segments and intersections should beused to display the data. This information will bepresented in the DCR along with a summary ofthe project traffic data including current andforecasted ADT values, peak hour and peak hourdirectional splits and percent of trucks.

Traffic signal recommendations will be includedin the report. For each signal location, thefollowing information should be provided:

• Phasing Diagram• Controller Equipment• Detection requirements• CCTV• Interconnection• Power Source

On all projects where the primary justification, oran important justification, of the project is toimprove safety, the DCR should include accidenthistory data and an analysis of the causes of theaccidents as well as a collision diagram.Estimates should be made of the accidentreductions expected if the improvement proposal(or alternatives) is built. The monetary value ofthe accident savings should be calculated over thedesign period of the project (normally 20 yearswhere geometric improvements are proposed).

A summary of the traffic analysis shall beincluded in the body of the DCR. The completereport is also included as a separate Appendix.

305 DESCRIPTION OFALTERNATIVES

In consultation with the Municipality, theengineer shall develop alternatives to be evaluatedthat respond to the project purpose and need tovarying degrees. The alternatives identified mayinclude separate horizontal alignments, profilevariations, typical section concepts etc., that canbe evaluated in a matrix form to qualitatively andquantitatively review the alternatives to identifymajor differences. The engineering, social,economic and natural environmental impacts foreach alternative under consideration must beaddressed.


Part 1 300-4

The horizontal alternative alignments will bedisplayed on aerial photographs for evaluation ofassociated impacts. The sheets will show theproposed centerline, stationing, proposedstructures, edge of pavement lines and affectedproperties, at a scale that is appropriate to theproject length and character.

A cost estimate will be prepared for eachalternative and include:

• Construction costs• Utility relocation works costs• Land acquisition costs

At this point, meetings will be held with variousMunicipality and Government Departments thathave a vested interest in the project. The engineerwill present the alternatives, review the evaluationcriteria and matrix form and discuss merits andadversities of the different alternatives.Comments and direction received at themeeting(s) will be factored into the alternativesevaluation matrix.

Finally, the analysis will conclude with adiscussion of the evaluation criteria for eachmatrix parameter, input/direction receivedconcerning the project and a summary discussionof the advantages and disadvantages of eachalternative studied. This will be followed by theengineer’s recommended alternative withsupporting justification for the selection.

306 DESIGN DATA

This section will document the design criteriaassociated with the recommended design conceptand specifically identify any exceptions from theminimum criteria established for the roadwayclassification.

It is very important that sufficient detail isincluded in the DCR so that future revisions tobasic design features and project scope are held toa minimum.

The following basic design criteria established inPart 2, Roadway Design, shall be included: • the functional classification of the road per

Part 1, Section 100, General Information.

• the minimum design speed(s), min.horizontal/vertical curve radii, sight min.distance (passing and stopping), max.superelevation and other design requirementsassociated with the classification of the road;

• the actual design speed(s), horizontal/verticalcurve radii, sight distance (passing andstopping), superelevation, etc. used for theproject;

• lane width, shoulder width, and bridge width;on the project

• cross slope;• grade;• horizontal and vertical alignment (actual);• horizontal and vertical clearance; and,• bridge structural capacity.

The design exceptions identified shall be preparedin a “Fact Sheet” format as described in Part 2,Section 100, General Design Criteria.

307 TYPICAL SECTIONS

The typical roadway cross sections and thedimensions of the lanes, shoulders, median(s) forboth the mainline and all ramps are to beidentified. The number of typical sections willdepend on the number of significantly differentroadway/pavement structure conditions. At aminimum, at least one section should be providedwhich depicts all facilities within the limits of theright-of-way (i.e., ramps, frontage roads, drainagechannels, etc.).

The type of roadway section, i.e., cut or fill,number of lanes, shoulders, pavement structuralsection, cross slopes, and any retaining walls arealso to be included. Drawings that illustrate thisinformation are to be included in the Appendix tothe DCR.

308 GEOMETRICS

The alignment, profile, and number of trafficlanes, including through lanes, auxiliary lanes,turning lanes and ramp lanes are to be plotted onan appropriately scaled plan. A scale of 1:500should be used for urban projects and 1:2500 forrural projects. The alignment should be displayedon an aerial base and the corresponding roadwayprofile shown below in a split sheet format.


Part 1 300-5

The text in this section should include a narrativedescription of the geometrics, constraints,controlling factors, drainage considerations andreference to the design exceptions. The plans areto be attached as an appendix to the DCR.

309 INTERCHANGE/INTERSECTIONCONFIGURATION

The various types of traffic interchanges aredescribed in Part 2, Section 500, Interchanges.The discussion in this section should identify thesite and project considerations which led to theselection of the interchange and intersection type.

The site considerations include:

• the constraints imposed by the existing andnearby transportation facilities

• proximity of adjacent interchanges• the standards and arrangement of the local

street system including traffic control devices• right of way controls• local planning• community impact, and cost topography.

The project considerations include:

• the speed, volume, and composition of trafficto be served

• the number of intersecting legs• crossing and turning conflicts• safety considerations• cost

The interchange/intersection alternatives shouldbe evaluated as a part of the alternatives analysisdescribed in Part 1, Section 305, Description ofAlternative, when viable options are identified forthe particular project. This is especially true forfreeway and expressway projects where theInterchange/Intersection type has a significantimpact on the project character, capacity andcost.

310 PARKING STUDY

In accordance with Part 1, Section 202.09,Parking Requirements, a parking study shall beprepared and included as part of the DCR.

The results of the study shall be summarized inthe body of the DCR, with the entire studyincluded in the Appendix.

The summary of the results shall include:

• the existing parking demand• the anticipated parking demand• the resulting parking shortfall (or excess)• the alternatives as to how the project can

provide adequate parking• cost comparison of parking alternatives• economic impact of inadequate parking• if required by the roadway classification, the

need for off-street parking facilities• the costs and right-of-way requirements

associated with each of the above alternatives• the recommended alternative to meet the

anticipated parking demand,• the conceptual design of the recommended

alternative (see Part 2, Section 211, Parking).

311 HYDROLOGY ANDHYDRAULICS

The Design Concept Report shall include aseparate section (study) for drainage designconcepts, which shall also include, when required,separate reports for flood plain encroachment andmajor waterway crossing studies.

The drainage design concepts section shalladdress the following items:

• Planning consideration for the overallwatershed considering the project and otherexisting and future development

• Assessment of existing and future conditions

affecting drainage areas, flow patterns, andflood levels

• Estimate of future development and its effect

on flows and flood levels • Drainage map showing topographic features,

watershed boundary, slope contours, drainageareas, existing drainage systems, proposedcross-drain locations (including peak flowvolume, design high water elevation andculvert size) and proposed conveyance


Part 1 300-6

systems (pipes and channels including flowdirection, sizes and peak flow volume)

• Hydrology calculations for drainage area

intercepted by the project to include peakrunoff volume flow rates from each drainagearea

• Proposed concepts for disposal of storm

water. • Design criteria, procedures, methodology, and

assumptions for analysis and design. • Proposed concepts for handling and disposing

of storm water during construction. • Recommended size and location of cross

drainage structures and channels, includingdesign high water elevation that might affectthe road profile grades or the roadwaylocation.

• Proposed concepts for on-site roadway

drainage collection, detention, and outfalllocations.

• Separate Flood Plain Study Report where the

roadway encroaches on flood plains eitherlongitudinally or transversely.

• Bridge Location and Hydraulics Report for

bridge or large box culvert waterwaycrossings.

311.01 PURPOSE

The purpose of the drainage design concept studyis to document the methodology and results of thehydrologic analysis and the rationale used indeveloping the roadway drainage system. It shalldefine the type, size, and location of crossdrainage structures and channels, and determineflood level elevations.

The drainage design concept study shall determinethe initial type, size and location of the onsiteroadway drainage system and determine outfalllocation(s). It shall also address any floodplainencroachments and the overall watershedplanning.

311.02 PLANNING & PREPARATION OFTHE DRAINAGE DESIGNCONCEPTS

The Municipality often is and should be perceivedas a developer of transportation facilities thathave the potential to stimulate secondary activityalong the transportation corridor just as a majorresidential development can stimulate commercialactivity. Accordingly, there is a requirement toaddress overall stormwater management needs inconjunction with existing and future developmentsplanned for the foreseeable future. Because thetransportation corridor often traverses severalwatersheds, the development of an adequatestormwater management plan can be severelyfragmented and significant problems created ifthere is a lack of coordinated planning amongconcerned parties.

To be truly effective, a stormwater managementplan should consider the total scope ofdevelopment (i.e. transportation, residential,commercial, industrial and agricultural).Department coordination with responsibleAgencies and other Departments is essential toensure that proposed facilities match existingones, and that they are consistent with the long-term needs of the area. Significant savings canoften be realised by planning overall combinedstormwater management facilities, even thoughthe roadway development is only a small part ofthe total system. In addition, the Municipality canprovide important information to other Agenciesand private developers wishing to develop acomprehensive stormwater management planwithout assuming responsibility for the planningand decision making process for the entirewatershed.

Accordingly, prior to design, a level of planningand coordination shall be undertaken by thedesigners that will properly locate facilities andadequately address the overall drainage needs ofthe overall watershed(s) in regards to existing andfuture (foreseeable planning) development. Thissection provides general guidelines and majorconsiderations for evaluating these factors duringthe planning process.


Part 1 300-7

311.02.01 Problem Categories

Planning for drainage and stormwatermanagement facilities should include aconsideration of the potential problems associatedwith stormwater quality and quantity. Severalcategories of data should be obtained andevaluated including:

• Runoff quality provisions• Runoff quantity determination• Flood plain delineation• Inventory of problem and future

developments• Development of alternative plan concepts• Consideration of multipurpose opportunities

and constraints• Hydrologic and hydraulic analysis of

alternative concepts• Benefits analysis and evaluation These are further defined as follows:

A. Quality: Several broad categories ofdegradation have been developed to delineate ordescribe levels of stormwater impacts:

• Aesthetic deterioration: Undesirable generalappearance features (dirty, turbid, or cloudy)and actual physical features (odors, floatingdebris, oil films, scum, or slime) are present.

• Dissolved oxygen depletion: When the oxygen

demand of bacteria is stimulated by theorganics, the subsequent reduction in oxygenlevels can disturb the balance between lowerforms and the food chain. Unoxidizednitrogen compounds (ammonia) can alsocause problems. This is of concern whendischarging into reservoirs, small, limitedflush, tidewater areas, and freshwaterstreams.

• Pathogen concentrations: High concentrations

of several pathogens can reduce theacceptable users of the receiving waters. Aconcern where discharge may be accessed fordomestic use and discharge near public useareas (bathing beach).

• Suspended solids: The physical build-up of

solids can cover productive bottoms, be

aesthetically objectionable, and disrupt flowand navigation.

• Nutrients: Accelerated eutrophication thatstimulates growth of aquatic vegetation cancause a water body to become aestheticallyobjectionable, deplete dissolved oxygen, anddecrease recreational value by creating odorand overgrowth. Advanced eutrophication canlead to sediment build-up, which reducesstorage capabilities.

• Toxicity: The two types of toxics generally

found in stormwater (metals andpesticides/persistent organics) may build upin sensitive areas over the long term. At highlevels, they can have serious shock effects onaquatic life. Low levels can becomesignificant by accumulation up the foodchain.

Quantification of the levels of contaminants thatare being washed off a roadway is complicated bythe variable effects of and the periods betweenstorm events. The contributory factors are rainfallintensity, street surface characteristics, andparticle size. The varying interaction of thesefactors makes it difficult to precisely estimate theimpact that discharge will have on water quality.

However, where it is suspected that periodicrunoff may have a serious quality effect upon thereceiving area, further investigation, analysis andmethods for solving the problem should bepresented for review and approval.

The quality control management procedureparticularly applicable to this region wouldconsist of diverting the first 8 to 10 millimeters ofrunoff into retention (often combined withdetention for peak quantity control) basins wherethe more concentrated contaminates andsediments can be contained. The volume ofstormwater is then allowed to dissipate slowly byseepage and evaporation, effectively trapping thecontaminates in the basin for periodic cleanoutand disposal in a sanitary land-fill as needed.

An exception is erosion and sediment control,which is often a significant component ofstormwater quality. In general, erosion andsediment transport should be limited by


Part 1 300-8

developing and implementing an erosion andsediment control plan which addresses bothtemporary and permanent control practices.

B. Quantity: Determinations of stormwaterquantity are primarily useful for evaluating andmitigating the impact of a project. Withoutdetention, land development increases peak runoffrates and volumes from storm events, which canlead to higher flood elevations. Appropriatehydrologic and hydraulic calculations presented invarious chapters of this manual should be made todetermine the required conveyance through theMunicipality’s project limits, and to aid inmitigating impacts to downstream structures anddevelopment.

Procedures contained in Part 2, Section 700,Roadway Drainage Design, should be used toevaluate the ability of a facility to accomplish thefollowing controls for a particular area:

• Provide positive drainage and runoffcollection to the minimum criteria for safepassage of traffic on the project roads andparkings.

• Reduce runoff rates when applicable by

increasing infiltration, and by storingprecipitation and runoff where it falls andreleasing it slowly.

• Protect areas subject to flood damages by

keeping runoff confined to drainage facilitiessuch as pipes or channels and by buildingappropriate flood control facilities.

• Maintain offsite flows, through the project

area. • Limit flood plain enroachment to acceptable

upstream/downstream flooding impacts. The following questions should be consideredwhen selecting the plan for disposal of stormwaterrunoff:1. Are existing drainage systems large enough to

handle runoff? 2. Are runoff estimates consistent with adopted

drainage plans and Municipality criteria?

3. Will the project require retention or detentionstorage areas to mitigate the impacts ofincreased runoff, or can the increase behandled by other project features?

4. Is there sufficient area to construct a retention

or detention storage within the project limits?Are alternative sites available for storage ofstormwater?

5. What are the groundwater and soil

conditions? Is there a high groundwatertable, or are there impermeable soil layers?

C. Flood Plain Encroachment: The primarydrainage consideration for facility location inhighway planning is the evaluation of the impactof flood plain encroachment for a steam or wadicrossing or where the road embankmentlongitudinally encroaches into the flood plainarea.

The following factors for locating a streamcrossing that involves encroachment within aflood plain area:

• Waterway characteristics (stable orunstable)• Geometry• Hydrology• Hydraulics• Alignment• Flood plain flow• Needs of the area• Economic and environmental concerns

A detailed evaluation of these factors is part ofthe bridge location and hydraulics study. When asuitable crossing location has been selected,specific crossing components can then bedetermined. When necessary, these include thegeometry and length of the approaches to thecrossing, the probable type and approximatelocation of the abutments, the probable numberand approximate location of the piers, theestimated depth to the footing supporting the piers(to protect against local scour), the location of thelongitudinal encroachment in the flood plain, theamount of allowable longitudinal encroachmentinto the main channel, and the required rivertraining works, to ensure that river flowsapproach the crossing or the encroachment in a


Part 1 300-9

complementary way. Exact information on thesecomponents is usually not developed until thefinal design stage.

Where the roadway embankment encroachessignificantly in a longitudinal direction into theflood plain, a separate floodplain encroachmentstudy must be made to evaluate the increasedflood depths and velocities that may impact,upstream and down stream properties.

Further details defining flood plain encroachmentare provided in Section 311.02.02.

D. Other Departments Coordination:Coordination between concerned agencies duringthe project planning phase will help produce adesign that is more satisfactory to all. Substantialcost savings and other benefits frequently can berealized for both the roadway and otherdevelopment projects through coordinatedplanning between the various GovernmentDepartments and private developers.

311.02.02 Flood Plain Encroachment andRisk Evaluation

When a highway project will encroach on a floodplain, careful consideration must be given to thepotential risks from the encroachment. Anyproposed project that encroaches on a flood plaineither transversely or longitudinally, and ispredicted to result in a significant adverse impacton natural flood plain values, a significantincrease in flood risk, or a significant change inthe potential for interruption of main accessroadways, emergency service or major services,must be evaluated with a complete hydraulicanalysis and a risk analysis, to be included in aseparate flood-plain study or a bridge locationand hydraulics study for transverse crossings.These separate reports must documentconsiderations of alternatives which do notinclude such encroachments. Significantencroachments will not be approved unless thereis no practical alternative.

The flood plain study (and/or bridge location andhydraulics study) shall include the following:

A. Hydraulic Analysis: The hydraulic analysismust provide the water surface profile elevations

before and after the proposed project in both theupstream and downstream directions for adistance to where it can be shown that no furtherimpact over pre-project conditions is influencedby the project for: (i) the design event storm, (ii)for the 100 year storm, and (iii) the maximumprobable storm (usually the 500 year event).Besides the peak water surface profile, theanalysis shall include the flow volumes, velocityprofiles (velocity at various points in the cross-section), and hydraulic structural alternatives thatwere evaluated to mitigate significantencroachment.

The frequency with which the highway orwatershed divide is likely to be overtopped shouldbe stated. If the overtopping flood is a 500-yearflood or greater, it should be stated. The locationof the overtopping should be indicated.

B. Economic Analysis: An economic analysisshould include a comparison of designalternatives, using expected total costs(construction costs plus risk and damage costs) todetermine the alternative with the Least TotalExpected Cost (LTEC). The comparison willinclude probable flood-related costs during theservice life of the facility for: highway operation,maintenance, and repair; highway-aggravatedflood damage to other property; and additional orinterrupted highway travel. Other costs includecrop damage, structure damage and publicinconvenience.

C. Study of Flooding Encroachments: Theflood plain study should include an inspection ofthe flood plain to determine the increase in thenumber of flood receptors and the increase in thedamage to present flood receptors that will resultfrom the expected increase in flood heights.Consultation with local citizens and otherDepartments should be initiated where necessaryto adequately assess encroachments.

D. Risk Assessment: All designs with floodplain encroachments should include an evaluationof the inherent flood-related risks to the highwayfacility and to the surrounding property. In thetraditional design process, the level of risk isseldom quantified, but is instead implied throughthe application of predetermined design standards.For example, the design frequency, backwater


Part 1 300-10

limitations, and limiting velocity are parametersfor which design standards can be set.

Two other approaches, however, are availablethat quantify risk on projects that involvehighway facilities designed to encroach within thelimits of a flood plain. These are risk assessmentand economic analysis. Risk assessment is asubjective analysis of the risks engendered byvarious design alternatives, without detailedquantification of flood risks and losses. It mayconsist of developing the construction costs foreach alternative and subjectively comparing therisks associated with each alternative. Economicanalysis (sometimes called risk analysis)encompasses a complete evaluation of allquantifiable flood losses and the costs associatedwith them for each structure alternative. This caninclude damage to structures, embankments,surrounding property, traffic-related losses andscour or stream channel change. The level ofexpense and effort required for an economicanalysis is considerably higher than for a riskassessment, and selection of the process to beused should be based on the size of the projectand the potential risk involved. A risk assessmentis usually more appropriate for small structuresor for structures whose size is highly influencedby non-hydraulic constraints.

Policy dictates that hydraulic facilities bedesigned so that highway facilities will performwithout significant damage or hazard to people orproperty during the appropriate standard designfrequency flood. Risks associated with floods ofmagnitudes greater than the standard designfrequency flood should be evaluated inaccordance with the risk evaluation levelspresented in this section. If warranted, a designbased on a lower or higher frequency flood maybe used. The minimum design frequency forbridges on main highways, however, is 50 years.

A typical example would be a major cross drainbox culvert for a primary highway. The standarddesign frequency would be a 50-year frequencyflood. A design based on this frequency shouldbe produced in the "traditional" manner, includingdevelopment of feasible alternatives. Thealternatives would be compared for cost and forrisks associated with the 50-year frequency flood.The lowest total cost structure that met the design

constraints would be the preferred design. Thisdesign should then be investigated for the 100-year flood.

311.02.03 Data Collection

Identification of drainage data needs should be apart of the early planning phase of a project,when appropriate procedures for performinghydrologic and hydraulic calculations areselected. Several categories of data may berelevant to a particular drainage project, includingpublished data such as precipitation, soils, landuse, topography, streamflow and flood history.Published mapping is usually inadequate, so fieldinvestigations and surveys are necessary todetermine drainage areas, identify pertinentfeatures, obtain high water information, surveylateral ditch alignments and survey bridge andculvert crossings. In addition, hydrologycalculations for a watershed or larger drainagearea will usually require some sort of topographicmapping. The preferred mapping is using aerialphotography showing contour elevations usingdigital techniques is preferred. Manual groundsurveys are usually adequate for smaller areas.The requirements in more detail are as follows:

A. Data Collection Procedure: Drainage datashould be collected before calculations areinitiated, under the following general guidelines:

1. Identify data needs, sources, and uses. Muchof this information will have to be provided inthe concept report and kept in the supportingfiles.

2. Collect published data, based on sourcesidentified in Step 1.

3. Compile and document the results of Step 2,and compare data needs and uses withpublished data availability. Identify anyadditional field data needs.

4. Collect field data based on needs identified inSteps 1 and 3.

5. Compile and document the results of Step 4.

B. Published Data: At present, there is limitedpublished data with regards to soils, land use,


Part 1 300-11

streamflow, flow histories, etc; however, athorough search for soils investigation recordsand existing utility/drainage systems should bemade from as-builts of other projects in thevicinity. Old newspaper records may also be asource of timing and pictures of past floodingevents.

C. Drainage Areas: If there is sufficienttopographic information for a project site fromreadily available sources (aerial mapping), a fielddetermination of drainage area may not benecessary, but spot-checking selected controlelevations is always advised. For those projectsites for which detailed information is notavailable, field survey work or aerial photomapping should be performed. In all cases, a sitevisit by the designer is mandatory to confirmdrainage area conditions.

Drainage areas shall be outlined on the drainagemap (preferably on a contoured photo base map).Drainage area boundaries should connect with thejob centerline, typically at high points in grade orat other locations where there is a definite divisionin the direction of storm runoff flow. After theoverall areas are plotted, the drainage area shouldbe sub-divided to show how the various sectionscontribute to the structures in the proposeddrainage or storm drain system.

All drainage area boundaries should be followedfrom project centerline around the area beingcovered and closed again to the roadwaycenterline. Ridges that do not establish an areadraining to the project should not be shown unlesspertinent to determination of runoff concentrationpoints or flow path segments. Exceptions to therule for closing all drainage area boundaries tocenterline are to be indicated clearly on the mapby notation. These notations should showlocation and elevation of breakover or diversion toor from the drainage area.

Typically, a drainage area should close to eachexisting culvert along the project, for eachprobable cross drain location to each inlet forpiped system, and protected overland flowentrances to channels. As an exception, wheretwo or more structures operate conjunctively todrain a single area, flow distribution informationshould be noted.

For urban type construction surveys, appropriatecity maps or specially prepared maps should bemarked to show the boundaries of total areascontributing to the project. Streets or otherdrainage facilities in these areas should be markedwith flow arrows. In many instances, elevationsmay have to be determined to accurately delineatedirection of flow in gutters or side of roadchannels.

All areas contributing to existing storm drainswhich drain to or across the project should beshown. In very flat terrain, it is often necessaryto develop profiles for cross streets and parallelstreets to make a definite determination ofdrainage areas.

Specially flown aerial photography should beobtained for most construction projects.Elevation contours and ridge lines usually can beindicated on the photographs utilizing digitizedcartography combined with ground based controlsurveys. When photographs are used, the fieldsurvey party should verify questionable pointsand supplement the information with structuresizes, elevations, and elevations as required.Drainage areas can also be determined by stereointerpretation of stereo paired photographs withspot field survey work as appropriate (usuallysufficient for smaller areas).

D. Drainage Maps: For roadway projects, thedrainage maps should be prepared on pre-formatted sheets that use a cross section gridprinted across the lower portion for plotting theproject profile. The profile is plotted to someconvenient scale according to need. For projectsinvolving interchanges, rest areas, urban streetsand the like, a supplemental drainage map thatshows only the plan portion on a sheet without aprofile grid is required. The supplemental map isprovided to show the small areas needed tocalculate pipe sizes for the tabulation of drainagestructures within these special areas.

The following data should be provided on the planportion of the map:

1. Physical land features affecting drainage,such as elevation contours, land use,vegetation cover, streams, wadis, reservoirsand tidal areas, together with past high water


Part 1 300-12

and date of occurrence, if available, andpresent water elevations with the dates of thereadings, as appropriate.

2. Existing drainage structures, showing type,size, flow line, flow direction, and any otherpertinent data.

3. Drainage divides and information, whereapplicable, to indicate the overland flow ofwater. Drainage areas on maps of urban andrural sections should be shown to theaccuracy necessary, depending on the systeminvolved. A guide to the appropriateaccuracy for a non-critical system isprovided. Critical systems usually require adrainage area determination within 2 to 3percent.

Size Accuracy

Drainage Mainly MainlyArea Impervious Pervious

(Hectares) (Hectares) (Hectares)0.0 - 0.2 0.02 0.040.2 - 2 0.04 0.082 - 4 0.08 0.24 - 8 0.2 0.48 - 20 0.4 0.820 - 40 0.8 240 - 80 2 4

>80 4 10

Inserts are used to show areas of suchmagnitude that the boundaries cannot beplotted at the regular scale. Proposeddrainage structures are plotted by symbolonly in the plan portion and noted bystructure number.

4. Aerial photography is desirable because itwill document the development and often thedrainage pattern which existed at the time ofdesign.

5. Design, base, and overtopping (or maximumprobable flood) discharge and stage valuesare required on all expressway and mainroadprojects for all cross structures that wouldback floodwater outside the project limits,regardless of structure size.

6. In the report, the various cross-drainculverts should be summarized by station,size, invert elevation and minimum culvertbackfill values for pH, resistivity, sulphates,and chlorides for the various alternateculvert materials.

The profile portion of the map should include thefollowing data:

1. Plot of the existing ground, done in a lightsolid line to the same horizontal scale as wasused for the plan portion.

2. Drainage map sheets with the profile blocksdeep enough to sufficiently show thenecessary profiles and cross-drain profiles.

3. Plot of the proposed profile grade line.

4. Plots of all proposed special ditches, exceptmedian, when horizontal and vertical scalespermit.

5. Plots of proposed cross drains, exceptmedian drains. Skew and pipe slope are notshown.

6. For urban projects, plot only the storm drainand mainline structures. Laterals are notplotted. Flow line elevations are postedalong the main.

E. Existing Features Survey: In areas drainingto a project site, all streams, wadis, ditches,reservoirs, drainage structures, and other possibleconflicting utilities should be shown. Flow lines,controlling grade elevations, and high waterstages should be documented for existingstructures. The concept report should note recordthe estimated reliability of flow and high waterobservations.

1. Survey Notes: The drainage survey notesshould show all pipe lines, culverts, and bridgesin place on the existing roadway. Pipe length,size, type, and conditions should be given. Thedesign for alternate culvert materials requiresaccurate information on the condition and lengthof service for existing culverts. Data oncorrugated pipe should include material (steel oraluminium), coatings, size, and type (annular or


Part 1 300-13

spiral) and size of corrugation. Flow lineelevations of pipes should be shown at both inletand outlet. For box culverts to be extended, anaccurate sketch should be made showing the sizeand length of the culvert, thickness of all walls,wings, and slabs, and the angle of the barrel withthe survey centreline. Elevations should be givenon the top of the bottom slab, top and bottom oftop slab, parapet walls, wings, etc., on each endof the culvert.

The type, length and width of roadway, locationof bents, number of piles per bent and type offootings should be shown for bridges in place.Profiles should be shown as centerline ofroadway, from the edge of pavement left and rightof centerline of survey, and under the bridge oncenterline of survey. The profiles shouldaccurately define the top and bottom of channelbanks and the channel bottom.

2. High Water Information : Reliable highwater information is necessary to evaluate floodelevations and establish roadway grades. Highwater elevations should be shown upstream of theproposed project, upstream of significant existingstructures, and at some point along or at the endof outfall ditch surveys. The location at which ahigh water elevation is taken should be clearlyrecorded in the field notes, along with the date andtime if available.

At many locations, it is not possible to obtaindocuments information on high water. In suchcases, elevation may be estimated by observationof natural growth, evasion marks or by othermeans. The survey crew should provide completeinformation on the methods used. The crew chiefshould attempt to obtain information from localresidents or maintenance personnel.

The soils investigation usually supplies watertable information within the project limits;however, the survey crew should note informationpertaining to standing water, areas of heavyseepage, or springs within the basin area.

3. Lateral Ditch Surveys: Most highway sectionprojects should routinely include lateral ditchsurveys at the locations of existing ditches,streams, wadis, swales, etc. The surveys shouldprovide a clear picture of existing conditions at

any location where water comes to and/or leaves aproposed project. They should clearly show thepath and approximate elevations of flow forexisting ditches and natural streams. Inflow datashould be provided for a distance sufficient toindicate the degree of channelization and thedirection of flow, usually a distance of 30 to 100meters.

Data on the outfall portion should extend farenough to determine the direction and degree ofchannelization and the rate of fall in watersurface, and to reach a point of positive and safedisposal. If ditch or channel work appearsnecessary, collection of topographic data shouldcontinue downstream to a point at which damageto adjacent property appears to be insignificant.

If the length of an outfall raises serious doubtsabout its usefulness, the field party shouldterminate the survey at 150 meters and note theapproximate distance to a suitable disposal point.This note should give the distance, the waterelevation at the approximate end, and a briefdescription of the topography (i.e., tidal bay,reservoir, wadi, etc.) into which the outfall willdrain if extended. The designers can thendetermine if a further detailed outfall survey isrequired.

The field survey for a lateral ditch should alwaysinclude property boundaries or plot walls/fences,which are often the determining factors in theultimate location of outfalls. With propertyboundaries marked, the design engineer is in amuch better position to determine the extent ofcross-sectioning needed to cover possiblealterations in alignment, and the design engineeris aware of the limitations in changes he mayconsider.

4. Bridge and Large Culvert Surveys:Locations of larger culverts and bridges oftenmust be detailed. The meander of both banks of astream for a sufficient distance upstream anddownstream to determine the approximate extentof any probable channel relocation should beobtained. This ordinarily can be shown within150 meters upstream and downstream from theproject. Any major overflow channels also shouldbe indicated within approximately the same limitsor within the limits that these channels leave and


Part 1 300-14

return to the main channel. Meandering channelsclose to and approximately parallel to the projectcenterline should be located carefully and cross-sectioned.

Across flood plains where the proposed projectfollows an existing fill, cross-sections shouldextend far enough to provide a record of naturalground profiles right and left of the project. Anywashouts or significant swales, side wadiis,sloughs or ditch outlets should be noted clearly inthe topography.

Recommendations for significant realignment orimprovement of an existing channel often willcome as part of the structure design, making itnecessary to survey a designated location. Forthis reason, specific channel location surveysshould not be made during the initial locationsurvey unless the need for and logical location ofsuch changes are apparent.

Required data on existing roadway and railroadstructures upstream and downstream should beidentified by the drainage engineer so it can beincluded in the survey. For fills and structures inreasonable proximity to the project, a profile ofthe existing roadway showing structure openingsshould be established relative to the project data.For structures farther removed, it is oftenadequate to include only a profile and high waterinformation. The information should includeobservations on scour, washouts, or otherpertinent hydraulic factors. Where scour issignificant, cross-sections should be taken todetermine the depth and extent.

Appropriate flood elevation data should beobtained for bridges. If reliable data is notavailable, that fact should be noted by the fieldparty. The extreme high water, its location, andthe approximate date of its occurrence should berecorded, if available. Other elevation high waterthat can be dated should also be recorded whenpractical. If possible, a "normal" high waterelevation, or one which can be expected to recurabout every 2 to 3 years, should be determined.A normal elevation that would be expected toprevail through seasons of average rainfall shouldbe recorded.

Field surveys at existing bridges should includethree profiles: the first on the survey centerline,the second approximately 10 meters right of thesurvey centerline, and the third approximately 10meters left of the survey centerline. The purposeof the second and third profiles is to provide dataat the edge of the bridge. The centerline profileshould show the roadway grades and the groundline under the bridge. Cross-sections should betaken across the bridge area to furnish elevationsfor plotting the face of the slopes and for accurateplotting of low water channels. All profilesshould include points indicating the top of the lowwater banks (the edges of the low water channel),water level at the date of the survey, and theprofile of the stream bed along the survey lines.Where new lanes for the roadway are to belocated at bridges from a survey along the oldroadway using cross-sections for approximateelevations, it is necessary that the three profiles berun along each side of the new roadway,furnishing complete channel limits and elevationson each profile. These surveys should includecorrected stationing referenced to the road survey,showing station and elevation equalities ifnecessary. At expressways, where a single profileis run along the centerline of the median for theroadway survey, the three profiles and cross-sections should be performed for each lane at allbridges.

5. Documentation: Documentation involves thecompilation and presentation of all pertinentwatershed data collected for the project. It shouldinclude (but is not limited to) basic items such asdrainage area and other maps, field surveyinformation, published data references,photographs, and narratives from witnesses ofhistoric floods. This data should be maintained inthe permanent records. The orderly compilationand presentation of watershed data will expeditethe design, review, and evaluation phases of adrainage project

311.03 STORM WATER HYDROLOGY

To convert precipitation to stormwater runoff,hydrologic calculations are generally used toquantify the abstractions (precipitation losses)which occur as part of the hydrologic cycle.Virtually all drainage and flood plain calculationsonly consider infiltration, interception, and


Part 1 300-15

surface storage losses, since short time scales willusually render losses from evaporation andtranspiration insignificant. A possible exceptionto this usage is for land-locked watersheds.

Since the governing relationships of hydrology arecomplex and, unlike problems in engineeringmechanics, are not easily solved through directuse of the fundamental laws of physics, a widevariety of hydrologic procedures have beendeveloped. Procedures for making time ofconcentration and rainfall excess calculations,procedures for estimating peak runoff rates atgaged and ungaged sites, procedures fordeveloping design storm hyetographs, and floodhydrograph and hydrologic channel routingprocedures are contained in the drainage volumeof the design manual.

Drainage studies often follow a similar sequenceof calculations for all procedures, becauseprecipitation must be routed through watersheds,channels, and reservoirs. In most cases,stormwater runoff will be estimated using thefollowing general procedure:

1. Divide the watershed into appropriatesubareas to correspond with homogeneousland use conditions and the placement ofdrainage facilities such as inlets, reservoirs,and open channels.

2. Collect and analyze watershed data.

3. Establish design storm conditions asappropriate for the procedure selected.

4. Calculate the peak runoff rate or determinethe time distribution of rainfall excess. Nofurther calculations are generally required ifonly the peak runoff rate is desired.

5. Develop a unit hydrograph for thewatershed, if a runoff hydrograph is desiredand the procedure selected uses a unithydrograph.

6. Develop the direct runoff hydrograph, usingthe unit hydrograph and rainfall excessdetermined above, as appropriate.

7. Perform downstream channel and reservoirroutings, as appropriate.

8. Record the necessary calculation processand the results on the appropriate drainagemaps, and in the drainage section of theDesign Concept Report, as appropriate.

311.04 OPEN CHANNEL HYDRAULICS

The consideration of open channel hydraulics isan integral part of roadway projects in whichartificial channels and improvements to naturalchannels are a primary concern. Procedures forperforming uniform flow calculations that aid inthe selection or evaluation of appropriate channellinings, depths, and grades are included in thedrainage volume of the design manual. For mostartificial channels, the most desirable lining isnatural, emerging vegetation, with grass used toprovide initial and long-term erosion resistance.If natural vegetation, usually grass, is unfeasible,concrete lining is used. Also, flexible liningscomprised of rock riprap asphalt or articulatingconcrete grids can be used for preventing erosion.Allowable velocities and permissible depths offlow are provided in the drainage volume of thedesign manual, along with various adaptations ofManning's Equation suitable for evaluatingchannel capacity.

Open channels can be generally classified as thosewhich occur naturally and those which are man-made or improved natural channels. The later,called artificial channels, include the followingtypes in use on most roadway project:

1. Right-of-way ditches which usually acts asan overland flow interceptor ditch collectingwater before it reaches the roadway.

2. Roadside or roadway ditch and (sometimecalled the “borrow ditch”)

3. Median ditches on divided highway.4. Outfall ditches for connecting and carrying

flows from ditch types 1, 2 and 3, a shortdistance to a natural outlet or to another,larger conveyance channel.

5. Lateral ditches are a larger size channel,usually used for continuing upstream flowspast the project area.

6. Canals are large size conveyance channels.


Part 1 300-16

Each of these channel types are artificial systemsdesigned to provide specific drainage capacities.The right-of-way ditch functions as a type ofrelief ditch, handling drainage needs other thanthose for the roadway and thus freeing roadsideditches from carrying anything except roadwayrunoff. Right-of-way ditches can also act asinterceptor ditches to provide a method forintercepting offsite flows or subsurfacegroundwater flows above cut slopes, therebycontrolling slope erosion.

In general, roadside or median ditches arerelatively shallow trapezoidal channels or swales(which are shallow triangular channels). Bothtypes are designed to handle local surface runofffrom roadway surfaces, or to lower water tableelevations by intercepting groundwater. In somecases, they may also handle other than projectdrainage. Outfall ditches or canals are designedin most cases as receptors of runoff fromnumerous secondary drainage facilities, such asside ditches or storm drains. The use of aroadside ditch as an outfall ditch is notrecommended, since its probable depth and sizecould create a potential hazard.

311.05 BRIDGE HYDRAULICS

Bridge hydraulic designs shall be documented inthe Bridge Location and Hydraulics Report(BLHR). Design information shall besummarised on the Bridge HydraulicsRecommendations Sheet (BHRS). The format forthe BHRS is provided in Section 3.11.

BLHR and the BHRS shall be prepared for theprojects listed below:

1. Bridges and large culverts (culverts largerthan 1800 mm dia pipes or 1200 mm x1200m box culverts) on new alignments

2. Bridge and large culvert replacements onexisting alignments

3. For other bridge and large culvert projectsinvolving actions within the Base FloodPlain (work within the 100 yr. Floodelevation) e.g., bridge widening and largeculvert extensions.

311.05.01 Bridge Location and HydraulicsReport

A. Documentation: Documentation shall beprovided in detail commensurate with thecomplexity of the project. Documentation shallbe sufficient enough so that an independentengineer with expertise in bridge hydraulics, butnot involved with the design, can fully interpret,follow and understand the logic, methods,computations, analysis and considerations used todevelop the final design.

Documentation for bridge and large culvertdesigns shall include as a minimum the following:

1. Hydrologic analysis including sources of dataand methodology.

2. Alternative analysis or evaluation of structuresizes (length and vertical height/clearance).This evaluation shall be done consistent withDepartment criteria for bridge hydraulicdesign and shall include consideration of:

a. costb. design standardsc. structure hydraulic performance,

including backwater, velocity and scourd. Impacts of the structure on adjacent

propertye. environmental impacts

3. The alternative analysis shall include thereasons for selecting the recommendedstructure and a clear explanation as to why itis the most economical structure for the site inquestion. As a minimum, the followingstructure sizes shall be evaluated:

a. The minimum structure size required tomeet hydraulic standards for vertical andhorizontal clearance, scour andbackwater.

b. Existing structure size if applicable.c. The recommended structure size if

different from (a) or (b).

4. Design recommendations for bridgesrecommendations shall include:


Part 1 300-17

a. Bridge length, and justification for thelength, including locations (stations) ofabutments

b. Channel excavation requirementsc. Minimum vertical clearanced. Minimum horizontal clearancee. Abutment type and orientationf. Pier orientationg. Scour depths for the design flood, 100-

year flood and maximum probable flood(usually the 500-year flood).

h. Scour protection requirements forabutments, piers and channel

i. Deck drainage

5. Documentation of large culvert hydraulicdesigns shall include hydraulic calculationsand recommendations for the following:

a. Culvert Size, and justification for thesize, barrel length and location

b. Peak water surface profiles and cross-section velocity profiles for the designflood, the 100 yr flood and the maximumprobable flood for a distance 150 metersupstream, through the culvert to adistance 150 metres downstream.

c. Upstream and downstream invertelevations.

d. Endwall type for entrance and outlet,including the need for an improved inlet.

e. Skewf. Inlet end and outlet end scour protection

requirements

6. Final project plans shall show the peakstages, peak discharges, peak velocities, andpeak scour predictions for the design flood,the 100 year flood and the maximumprobable flood that can be expected to flowthrough the structure.

B. Report Outline: An outline of items thatshould typically be considered in the preparationof a BLHR is given below. Non-applicable itemsshould be so indicated rather than omitted withoutcomment. Additional information may beappropriate at unusual sites.

The BLHLR should be divided into two basicsections: Preliminary Information and DesignData. These sections are then broken down into

the subsections identified below. Rather than aformal item by item approach, a narrativedescription of the site and the hydraulicsrecommendations is suggested.

Preliminary Information

A. General Site Location

1. Highway Description

a. Type (expressway, main, secondary,rural, urban, etc.)

b. Lanes (two, four, divided, limited across,etc.)

c. Importance (main access between townsand borders, military route, alternateroutes available, etc.)

2. Topography of site and basin3. Location: small scale map with site located

B. Potential Site Problems

1. Land Use (obtain from responsibleDepartment)

a. Encroachment on the flood plainb. Recreational usec. Domestic water supplyd. Security area

2. Channel Stability

a. Bank stabilityb. Bends and meandersc. Potential for natural change of channeld. Aggradation or degradation of bottome. Scour history

3. Potential Water Stages

a. Flood history (dates; stages; source ofinformation; extent of flooding;approximate frequency; damage tostructure, embankment or highway)

b. Potential backwater from other streamsor rivers

c. Reservoirs of flood control projects(Department and status)

d. Tidally affected (mean high and lowwater)


Part 1 300-18

e. Other controls, if anyf. Normal high and mean high water stages

4. Clearances (horizontal and vertical)

a. Drift at flood stage (not necessarily atpeak backwater stage)

b. Navigation at mean high water or normalhigh water stage

Final Design Data

A. Inventory of Existing Crossing(s)

1. Location in relation to crossing(s)2. Determination of drainage area (when

significantly different)3. Physical data on structure(s) (size, type,

spans, foundation type, low member,available waterway area)

4. Flood history5. Evaluation of hydraulic adequacy of

structure(s) (Note: This data should beobtained not only for the site underconsideration, but upstream and downstreamcrossings as well)

B. Selection of Design Flood

1. Importance to highway system2. Importance to life and property3. Conveyance of design, 100-year and

maximum probable flood (under orover/under the highway)

C. Hydrologic Analysis

1. Site review (extremely important)2. Interview with persons providing flood

history data3. Review of available flood records

(Department, newspapers)4. Review of available stream gages in vicinity5. Definition of drainage area above site6. Evaluation of potential watershed basin

changes (20-year minimum)

a. Urbanizationb. Channelizationc. Water management practices

7. Determination of design discharge anddevelopment of discharge-frequency curve

8. Determination of design flood stage anddevelopment of stage-storage-frequency curve

D. Hydraulic Analysis

1. Bridges

a. Determination of permissible upstreamwater surface

b. With bridge length set to minimumcriteria or environmental controls,determination of backwater

c. Adjustment of (b) if required to satisfy(a)

d. Check of conveyance for 100-year floodand maximumbable flood; adjustment ofbridge length if required

e. Evaluation of scour potentialf. Evaluation of need for channel changesg. Evaluation of need for bank protection

including limits of protection, type,materials, and specifications

h. Evaluation of need for spur dikes andother training devices

i. Evaluation of effects of construction andtemporary activities

j. Evaluation of effect on downstreamstructures and properties

2. Large Culverts (any cross-drain culvert largerthan 1800 mm dia pipe, or 1200mm x 1200mm box culverts)

a. Determination of allowable headwater(AHW) and design storm tailwaterelevations

b. Selection of trial culvert sizec. Evaluation of culvert for abrasion,

corrosion, debris, scour, suitability forimproved entrance, etc.

d. Design of inlet and outlet scourprotection, if necessary

e. Check of conveyance of 100-year floodand max. probable flood

f. Evaluation of effect on stream stability.g. Evaluation of effect on fish and wildlife,

if applicableh. Evaluation of effect of channel changei. Evaluation of effect on downstream

properties and structures


Part 1 300-19

E. Additional Survey Data of Proposed Site

1. Data sufficient to prepare a contour map(intervals at 30 cm or 60 cm depending onscale); required distance upstream anddownstream will vary with site

2. In lieu of (1), a minimum of three crosssections will suffice for some cases(upstream, at, and downstream of site)

3. Vegetation, estimated bed load, bottom soilmaterial and soil properties, and other generalsite parameters

F. Departmental Coordination

1. Contact Departments involved and identifywhat other projects may be affected by theculvert/bridge

2. Investigate possibility or necessity for acooperative project

It is also suggested that a checklist of requireditems for each site be prepared and given to thesurvey crew to ensure complete data will beobtained with a minimum of supplemental orunnecessary effort.

311.05.02 Bridge HydraulicsRecommendations Sheet (BHRS)

The BLHR is a full size drawing, to be includedwith the BLHR. It is divided into severalinformation blocks, which must be as completelyfilled out as is appropriate for the design andlocation. The BHRS must always include theProject Number and the Bridge Number as perthe drainage map in the title box.

The information requested for existing bridge orlarge culverts near the site includes foundations,overall length, span length, type of construction,area of opening at high water, roadway width,and the low member elevation. The area ofopening at high water generally refers to the flowarea available through the existing structurebelow the water surface determined for a designstorm frequency.

The BHRS hydraulic design data section shouldinclude water surface elevations and severalcategories of flood data for various events,including the maximum event of record, the

design flood, the base (or 100-year) flood, andeither the overtopping or maximum probableflood, whichever occurs first. The overtoppingflood is the one in which flow crosses thehighway, or spills into another watershed orthrough a relief structure. The max. probableflood is normally a 500-year event. Flood dataincludes stage elevation, discharge, averagevelocity (on larger crossings a velocity profileacross key cross-section is usually needed) andexceedance probability.

Water surface elevations are classified as normalhigh water for non-tidal areas and as mean lowand mean high water for tide-influenced areas.Normal high water is defined as the 2-year event;mean low water and mean high water data can beobtained from the admiralty charts.

Hydraulic recommendations should include thebeginning and ending bridge stations, data on thechannel section (including any excavation),navigation and drift clearances, scour prediction,slope protection, and deck drainage.

Space should be provided for a small scalelocation map outlining the drainage area. A planview of the existing and proposed bridge areamust also be included. The scale shouldadequately depict the area adjacent to thestructure, including existing and proposedcontours. Drainage areas for very flat siteswarrant careful delineation since only one or twocontours may occur. For a bridge, a profile of thechannel section should be shown; for a largeculvert, the culvert centreline should be profiled.The profile should show channel work and bridgeend treatment. If necessary for clarity, bridgeends should be drawn at a larger scale.

The assumed configuration, deck drainage, andscour recommendations need to be approved bythe Municipality before plans are completed.This review provides an opportunity to evaluatethe impact of substantial changes on the hydraulicdesign conditions.


Part 1 300-20

311.06 STORMWATERMANAGEMENT USINGRETENTION/DETENTIONDESIGN

In general, retention refers to stormwater storagewithout access to a positive outlet, while detentionfacilities offer temporary storage accompanied bycontrolled release of the stored water. Wetdetention typically has a pool of water below theoutlet elevation; dry detention is typically placedwith the basin bottom above the seasonal highwater table. Retention and detention can be usedseparately or together in storage basins as siteconditions and management objectives require.

Historically, "detention" basins are used onlywhen such use reduced the outfall size (byreducing the peak discharge) enough to justify thecost. An additional benefit is that they can alsobe effective in improving stormwater quality.

The drainage volume of the design manualprovides general design criteria forretention/detention basins as well as proceduresfor performing preliminary sizing and finalreservoir routing calculations. The StorageIndication Method is presented as an acceptablemethod for detention calculations. Exfiltrationcalculations may be required for certain retentionsystems for estimations of percolated dischargerates.

Land-locked drainage areas will require retentionstorage areas designed to meet specialconsiderations.

The collection of field and published data for theplanning and location of retention/detentionfacilities should be coordinated so that it can beaccomplished concurrently with other aspects of aparticular project. A general discussion of datacollection procedures is presented in Section311.02.03.

A key element to proper planning ofretention/detention facilities is the selection ofpotential sites that will provide control of bothflooding and stormwater quality. Other importantconsiderations include:

• Runoff quality requirements• Stormwater management master plan

• Conveyance of drainage to the site• Availability of land• Suitability of site for water storage• Availability of suitable outlet point• Adjacent land use• Roadway control elevations• Soil infiltration capability• Water table fluctuations• Outfall high water elevations• Type of facilities proposed• Safety and maintenance requirements

Planning for retention/detention facilities shouldbe co-ordinated with the evaluation of borrowrequirements for the project. To the maximumextent possible, excavation from construction ofthe retention/detention basins should be used asfill material. If borrow material is required forbasin embankments, it should be obtained withinthe project limits, if possible.

The objective of drainage design is to provide thenecessary roadway drainage facilities whichallows the public to use the roadway during timesof significant runoff and in a manner thatminimizes the potential for adverse effects onadjacent property and existing patterns.

The effect of the roadway on the existing drainagepattern, the potential flood hazards, as well as theeffect of floods on the roadway are to be assessedin the design process.

The engineer shall perform a drainage study inaccordance with current design methodology,requirements and criteria in the drainage volumeof the design manual. The criteria should identifysuch items as the hydrology method to be used,the design storm frequency to be accommodated,the allowable spread of water on the pavement tobe tolerated at the specified storm frequency andany other pertinent hydraulic criteria which is adesign control for the project. Applicability ofexisting Master Drainage Plans will be discussed.

The purpose of the drainage study is to identifypotential drainage problems for the proposedimprovement, to recommend solutions, and toestablish initial pipe and channel sizings andalignments consistent with the improvementconcept. The major drainage features shall be


Part 1 300-21

displayed on the roadway geometric plans in bothplan and profile.

Basic hydrologic conditions should be fullyquantified and discussed. Analysis ofpreconstruction hydrologic conditions should beperformed in order to evaluate hydraulics(capacity, velocity, flood over-topping elevationsetc.) of any existing structures and the impacts ofalternatives considered.

The engineer shall research and evaluate potentialfuture development (20 year planning horizon)within the watershed which may have an impacton future drainage flows and ultimately theperformance of existing or proposed hydraulicstructures.

The engineer shall carefully document andphotograph all existing drainage problems,carefully evaluate recommended solutions andassure existing conditions are not impacted byroadway improvements.

The engineer shall document drainage problems,design approaches, solutions, and initial hydraulicstructures requirements in a separate InitialDrainage Study which will be included in theAppendix. A summary will be presented in theDCR.

312 SUBSURFACEINVESTIGATIONS

Once the project location, horizontal and verticalalignment and structure requirements have beengenerally defined, the engineer will formulatesubsurface exploration and testing program. Theobjective of the exploration program, is toprovide, specific subsurface information alongsuccessive design sections or reaches of theproject. The data will allow some basicjudgments to be made, i.e., the most suitabletype(s) of foundations for structures andrecommended pavement designs to be developedduring the design phase.

In the case of either the structure borings orroadway borings, the geotechnical program willserve to reveal the type, severity and extent ofgeotechnical design problems.

The Geotechnical Report will assemble the resultsof the subsurface exploration program, analyze,and make geotechnical engineeringrecommendations using the field boring and labtest data. This will be presented in an engineeringreport, prepared by the engineer for the projectand included in the Appendix. The results will besummarized in the DCR.

The Report is to contain the followinginformation:

• Summary of previous geotechnicalinvestigations

• description of the program undertaken toidentify geotechnical and subsurface elementswhich affect project design

• results of surface visual observations• groundwater data• a summary of the information obtained from

and the location diagram of the soil borings• the general description of the subsurface

geologic strata obtained from the soil borings,including any areas of unacceptable soilconditions

• particle size analysis and potential for scour• results of any material testing• analysis and recommendations for

embankment construction includingsettlement and surcharging

• an analysis and preliminary recommendationsfor pavement structural section andfoundations.

313 BRIDGE TYPE SELECTION

Selection of the most suitable type of structureinvolves investigating alternate superstructure andfoundation types including variation of spanlength, structure depth and number of girders todetermine the best bridge type and arrangementfor a particular site. This is an iterative phasewhere assumptions must be made and laterverified or modified during the process. Detaileddesign should not be performed unless it isnecessary to confirm the adequacy of a concept.

When performing the concept studies thefollowing shall be considered as a minimum:

• Cost• Constructability• Maintenance


Part 1 300-22

• Aesthetics

Sketches should be made of the variousalternatives investigated and included in thereport.

Both the vertical and horizontal clearances shouldbe checked to ensure that adequate clearances areprovided. Inadequate vertical clearance willnecessitate a change in either profile grade orsuperstructure depth while inadequate horizontalclearance may necessitate a change in spanlength.

The geotechnical aspects of the site should beconsidered since the foundation type andassociated cost may influence the type of bridgeselected. An initial (stage one) subsurfaceexploration and testing program will beperformed in parallel as described in Part 1,Section 312, Subsurface Investigations, and willbe used to determine foundation type and costs.

Traffic requirements must be investigatedincluding any detours or phasing requirements.These requirements will be addressed in thediscussion detailed in Part 1, Section 320,Construction Staging.

313.01 BRIDGES OVER WATERWAYS

For waterway crossings, coordination with theproject drainage requirements will be necessary.The designer should obtain the Initial DrainageReport and thoroughly review the contents beforestarting the analysis of alternatives. Fornavigable crossings, the channel width, verticalclearance, pier protection and navigational aidsshould be investigated and discussed.

313.02 WIDENINGS/REHABILITATION

On projects involving widenings, in addition tothe requirements for new bridges, the followingitems should be investigated:

• The existing structure should be checked forstructural adequacy.

• The condition of the existing deck joints.• The condition of the existing bearings.• The condition of existing diaphragms on steel

girder bridges.• The existing foundations.

• The existing waterway opening, vertical andhorizontal clearances.

• The need for adding approach slabs.• The adequacy of existing bridge rail.

When the above items have been investigated,preliminary design can proceed by studyingalternatives. Possible alternatives include:widening to one side, widening symmetrically onboth sides or replacing the bridge with a newstructure. Approximate costs based onpreliminary quantities and unit costs associatedwith each solution will be required.

313.03 BRIDGE SELECTION REPORT

The preparation of the Bridge Selection Report isthe final activity in the preliminary design phase.This activity involves incorporating the contentsof the Initial Drainage Study, and theGeotechnical Report to produce a final BridgeSelection Report and develop the preliminaryplans for the selected alternative. The preliminaryplans consist of the General Plan and GeneralNotes and Quantities Sheets. The preliminaryplans are not considered complete until thedrainage report and geotechnical foundationrecommendation is received and incorporated inthe plans.

After fully considering the above factors todetermine the proper structure type, the engineerwill discuss the architectural features with theappropriate Municipality Departments. For largeor controversial projects, approval by theExecutive Council or higher authority will berequired. These may be individual or jointdiscussions as dictated by the size, location,complexity, and sociological, economical,ecological and environmental demands of theproject.

Through these discussions a structure witharchitectural features that are compatible withstructural, safety and site requirements can bedeveloped.

The completed Bridge Selection Report shallinclude a general plan of the bridge. This reducedplan reflects the bridge geometrics, architecturaltheme, the bridge substructure and the type offoundations. A complete discussion of the cost


Part 1 300-23

and feasibility of alternative designs must beincluded. This is especially important for unusualand major structures. The Bridge SelectionReport will be included as an Appendix to theDCR.

The results of bridge type selection process willbe summarized in the DCR. The factors that ledto the selection of the preferred alternative will bethoroughly discussed. The proposed structuresshould be described and address:

• Foundation Type• Substructure• Superstructure• Architectural Features• Vertical and Horizontal Clearance• Other Key Factors

The General Plan shall be included in theDrawings (A3 size) that will accompany theDCR.

314 UTILITY IMPACT ANALYSIS

Utility impacts are a key project issue, especiallywithin existing transportation corridors. Datacollection and coordination with the variousagencies/departments is discussed in Part 1,Section 200, Design Concept Development. Thesecond phase of work includes analysis of theexisting and proposed utilities with respect toeach alternative in order to permit estimation ofcosts and evaluation within the alternativesmatrix.

Utility corridors including proposed ServiceReservations should be identified and indicated onthe typical sections and roadway plans included inthe DCR. For urban projects, the location ofservice reservations will affect the roadwaygeometrics including parking areas, green areasand the proposed pavement surfacing.

The DCR will include a through discussion of theutility impacts and a tabulation of the existingutility inventory as follows:

• Item Number• Owner• Description• Station

• Location• Status• Remarks

The DCR will summarize the impacts for eachmajor utility (water, sewer, telephone, irrigation,electrical). The responsibility for design andconstruction of the facilities will be addressed.Schematic plans showing the major existing andproposed utilities should be prepared and includedin the drawings section. Recommendations willbe given for general utility relocation schemes andfor resolution of specific utility conflicts.Associated utility costs will be included in thepreliminary cost estimate.

For larger projects a separate Utility Reportshould be prepared and included as an Appendixto the DCR.

315 SOCIOECONOMIC ANALYSIS

An analysis and discussion of the socioeconomic-data per the requirements described in Part 1,Section 202, Environmental Factors InfluencingDesign, shall be included in the DCR. Each ofthe topics covered in Part 1, Section 202,Environmental Factors Influencing Design shallbe included or, if not relevant, it should be sostated including the reason why it is not relevant.

For any of the topics which are not relevant, priorapproval from the Municipality is required toexclude the issue from the DCR. The requiredinformation as to the reasons why the topics arenot relevant shall be summarized in a conciseTechnical Memorandum accompanied bysupporting documentation as necessary. TheMunicipality shall make a determination as to therelevance of the topic based on this information.The Technical Memorandum and supportingdocumentation is to be included as a separateappendix in the DCR.

316 AGRICULTURE IMPACT

Agricultural resources are important to man’ssurvival and therefore must be preserved to thegreatest extent possible. The Consultant shallidentify the potential impact that the proposedproject alternatives may have on these resourceswithin the study area. Primarily, this involves


Part 1 300-24

determining whether or not the project willdirectly impact (i.e. irreversibly commit ) landthat is presently used for agricultural purposes.In the description of impact, the Consultant shallidentify whether the land is actively farmed orfallow as well as the types if crops that would beaffected. Impacts will be quantified in hectares.Indirect impacts will also be identified anddescribed. These may include, but are not limitedto, the potential description of the existingirrigation system or pollution of nearbyagricultural lands from untreated stormwaterrunoff. Impacts associated with each projectalternative will be compared and the alternativewith least agricultural impact shall be identified ifsuch an alternative exists.

317 PUBLIC FEEDBACK

Public involvement is an important aspect in theoverall success of a project. At the onset of theproject, the consultant shall develop a PublicInvolvement Plan that will establish the approachto be used to coordinate project planning anddetails with the public. In addition to keeping thepublic informed of the project, the plan will alsoprovide the public with the opportunity tocomment at various stages of projectdevelopment. By soliciting and activelyconsidering public input, the Consultant is morelikely to produce a design that is economicallyfeasible and acceptable to the public.

This section of the DCR should briefly describethe elements of the Public Information Plan,including the location and scheduling of publicinformation meetings, workshops, consensusbuilding sessions or any other forums aimed atsoliciting public input. A summary of theprimary issues raised by the public should bepresented along with a discussion of how theseissues have been addressed during thedevelopment of the project, and whether or notconsensus has been reached. A file should bemaintained as backup for each public meetingthat contains a list of participants and the issuesraised.

318 SIGNING AND PAVEMENTMARKINGS

Signing Concept plans will be developed to showthe major guide signs required for the proposedfacility in accordance with the MUTCD andcriteria included in Part 2, Section 900, TrafficEngineering. It may be necessary to includesigning outside of the project limits. New signs ormodifications required to existing signs shall beclearly identified. The signing requirements shallbe displayed on a reduced scale version of theproject geometrics sufficient to show the requireddetail. Proposed guide signs should be illustratedgraphically with leaders pointing to the signlocation. Signing requirements associated withthe construction staging/detour scheme shouldalso be discussed.

The signing and lighting concept plans will beincluded in the drawings section of the DCR.

319 LIGHTING CONCEPTS

This section should begin with a discussion of thedesign criteria that governs the location oflighting, the type of lighting relevant to theroadway classification or route and the method ofillumination analysis. Applicability orconformance to existing Master Lighting Plansmust be considered. Alternative types of lightingsuch as high mast at major interchanges shouldalso be addressed. The typical spacing betweenlight sources, and the compatibility with adjacentor intersecting lighting system will be shown andillustrated on schematic plans.

320 CONSTRUCTION STAGING

Maintenance of traffic during construction canhave a significant affect on the surrounding trafficsystem, in terms of public convenience, design,cost and the duration of construction. The DCRshall include a discussion as to how constructionof the project will be staged including:


Part 1 300-25

• Number of Stages• Erection of Falsework• Anticipated Detours• Duration of each Stage

The final design plans will generally be preparedin conformance with staging described in theDCR.

321 COST ESTIMATE

The DCR preliminary cost estimate must be asrealistic and accurate as possible. The degree ofeffort and detail for each project is expected tovary depending upon the complexity andsensitivity of the project-related issues.

The preliminary cost estimate should be preparedusing the “Preliminary Project Cost Estimate”form (Figure 300.02) to summarize the individualbills. This is intended to standardize the formatand type of items that need to be considered in theproject consistent with the General Specifications.Similar forms must be developed for each billsection to back-up the summary, including theestimated quantities and unit prices. It isimportant that all known items of work beidentified and estimated. In some instances, not allof the items can be identified at this stage and anappropriate contingency factor should be appliedto reflect possible increases such as modificationof the project limits or adding decorative features.

322 CONCLUSIONS/RECOMMENDATIONS

This section will include conclusions,recommendations, and their associated costs. Thename and title of the Project Engineer responsiblefor the preparation of the DCR as well as the AbuDhabi Municipality’s Engineer who served as theMunicipality Representative shall also beindicated.

323 APPENDIX

This section will be used for appending TechnicalMemorandums and the complete detailed studiesor reports including:

• Fact Sheet-Design Exceptions• Parking Study

• Initial Drainage Study• Geotechnical Report• Bridge Selection Report• Utilities Report• Traffic Analysis Report

324 DRAWINGS

The drawings prepared to illustrate and define thedesign concept should be presented in A3 formatas Volume II of the written report which is boundseparately in A4 format. The drawings shouldinclude the following:

• Typical Sections• Alternatives• Bridge General Plans• Roadway Plan/Profile• Signing and Lighting Concept Plans• Architectural Renderings• Construction Staging Schematics• Other project specific plans as required


Part 1 300-26

MUNICIPALITY OF ABU DHABIPROJECT NAME AND ROUTE NO.___________________PROJECT NUMBER_________________

PRELIMINARY PROJECT COST ESTIMATESUMMARY OF BILLS OF QUANTITIES

BILLNO.

BILL DESCRIPTION AMOUNT IN FIGURES

DH Fs

I GENERAL

II EARTHWORKS

III SUBBASE AND BASE COURSES

IV ASPHALT WORKS

V CONCRETE WORKS

VI SURFACE DRAINAGE SYSTEM

VII WATER WORKS

VIII PRESTRESSED CONCRETE WORKS

IX TRAFFIC MARKINGS AND SIGNS

X SITE LABORATORY

XI CONCRETE PILE FOUNDATIONS

XII METAL WORKS

XIII POST-TENSIONED CONCRETE WORKS

XIV EXPANSION AND FIXED JOINTS

XV IRRIGATION WORKS

XVI LIGHTING AND ELECTRICAL DISTRIBUTION WORKS

XVII TRAFFIC CONTROL SYSTEM

XVIII DAILY WORKS SCHEDULE

XIX TELEPHONE WORKS

XX SEWERAGE WORKS

XXI STREET FURNITURE

XXII PARKING STRUCTURE

XXV LANDSCAPING

TOTAL ESTIMATED COST

Figure 300.02Cost Estimate Worksheet


Part 2 100-1

PART 2ROADWAY DESIGN

SECTION 100GENERAL DESIGN CRITERIA

101 DESIGN SPEED

Design speed establishes specific minimumroadway design elements. These design elementsinclude vertical and horizontal alignment, andsight distance. Design speed relates indirectly toother elements such as pavement and shoulderwidth, and horizontal clearance.

Design speed is influenced by terrain, economicconsiderations, environmental factors, type andvolume of traffic, roadway functionalclassification, and adjacent land use (rural orurban).

Drivers expect consistent design speeds foradjacent roadways or roadways with similarcharacteristics. A driver in a mountainous areawould expect to travel more slowly than a drivercrossing the open desert. Further, the drivercrossing the open desert expects the travel speedto be similar for a divided road or a two-laneroadway. Normally, the design speed differencebetween adjacent segments should not exceed 10kph.

A roadway carrying a large traffic volume mayjustify a higher design speed than a less importantfacility in similar topography, particularly wherethe savings in vehicle operation and other costsare sufficient to offset the increased cost of rightof way and construction.. However, a lowerdesign speed should not be assumed for asecondary road where the topography is such thatdrivers are likely to travel at high speeds.

Subject to the above considerations, as high adesign speed as practical should be used. Thedesign speed for any section of roadway should bea constant value. However, during design,situations may arise in which engineering,economic, environmental, or other considerationsmake it impractical to provide the minimumelements established by the design speed.Examples include partial or brief horizontal sightdistance restrictions, like those imposed by bridge

rails, bridge columns, retaining walls, soundwalls, cut slopes, and median barriers.

The cost to correct such restrictions may not bejustified. Technically, this will result in areduction in the effective design speed at thelocation in question. Such technical reductionsshould be discussed and carefully consideredbefore accepted.

Design speed may be lowered, especially indensely developed urban areas. The design speedfor special projects will be established by theRoad Section. Maximum design speeds, as relatedto roadway classifications, are shown in Table100.01.

Table 100.01Design Speed

Roadway Terrain Desirable Min.Classification Type (kph) (kph)RURAL

FreewayFlat 140 120

Rolling 120 100Mountainous 100 80

ExpresswayFlat 140 120

Rolling 120 100Mountainous 100 80

Major CollectorFlat 100 80

Mountainous 80 60Minor Collector

Flat 90 80Rolling 80 60

Mountainous 60 40Local Access

Flat 90 80Rolling 80 60

Mountainous 60 40URBAN

Freeway 120 100Expressway 120 100

Arterial (Main Rd)Outlying 100 80Low Interruption 90 60High Interruption 60 40Frontage Road 60 50

Sector Road 50 40DIRECTIONAL RAMPS 80 60The maximum design speed varies by area on AbuDhabi Island therefore, refer to Figure 100.01 for theposted speeds on the Island. Posted speeds areconsidered to be approximately 85% of design speed.


Part 2 100-2

Figure 100.01Posted Speeds On Abu Dhabi Island


Part 2 100-3

102 DESIGN VEHICLES

For primary roadway projects, the design vehiclewill be a WB-12 intermediate semi trailercombination. For secondary and local roads, thedesign vehicle will be a single unit bus. Thedesign vehicles are as defined in a “A Policy onGeometric Design of Highways and Streets”,AASHTO, 1994. Refer to Section 405 foradditional information on design vehicles.

103 DESIGN TRAFFIC

103.01 DESIGN PERIOD

Geometric design of new facilities should bebased on estimated traffic 20 years aftercompletion of construction unless otherwisedirected by the Road Section.

Safety, resurfacing, restoration, rehabilitation,and operational improvement projects should bedesigned using current traffic volumes withconsideration for future growth.

103.02 RELATION TO DESIGN

The design designation is a simple, conciseexpression of the basic factors controlling thedesign of a given roadway. Following is anexample of this expression:

ADT (2000) = 9800 D = 60%ADT (2020) = 20,000 T = 12%DHV = 3000 V = 110 kph,

where:ADT (2000) = The average daily traffic, in

number of vehicles, for the constructionyear.

ADT (2020) = The average daily traffic forthe future year used as a target in design.

DHV = The two-way design hourly volume,vehicles.

D = The percentage of the DHV in thedirection of heavier flow.

T = The character of the traffic. This isexpressed by the truck increment (T) asa percent of the DHV (excludingrecreational vehicles).

V = Design speed in kph.

Within a project, one design designation shouldbe used except when:

(a) The design hourly traffic warrants achange in the number of lanes, or

(b) A decided change in topography dictatesa change in design speed.

The design designation should appear on thetypical cross section for all new roadwayconstruction projects.

104 ROADWAY CAPACITY

104.01 DESIGN CAPACITIES

Design capacity is the maximum volume of trafficfor which a projected roadway can provide aselected level of service. Design capacity varieswith a number of factors, including:

(a) Level of service selected.(b) Width and number of lanes.(c) Weaving sections.(d) Presence or absence of, and width of,

shoulders.(e) Grades.(f) Horizontal alignment.(g) Operating speed.(h) Lateral clearance.(i) Side friction generated by parking, drive

ways, intersections, and interchanges.Volumes of trucks, buses, recreationalvehicles, bicycles and pedestrians.

(j) Percentage of trucks, buses, andrecreational vehicles.

(k) Spacing and timing of traffic signals.

Design capacity is based on the factors above,design year traffic and operation at a specifiedlevel of service (LOS).

Broadly defined, in terms of traffic flow, LOS Ais associated with free flow traffic; LOS Bindicates reasonable free flow; LOS C is stableoperation; LOS D is lower range of stable flow;LOS E is unstable flow; and LOS F indicatesforced flow.

Design levels of service for various conditions areshown in Table 100.02. The highest feasible LOSshould be selected and used for design, except


Part 2 100-4

where unreasonable costs or environmentalconstraints would dictate a lower LOS.

Level terrain is defined as a roadway on whichtrucks can maintain speeds that approach or areequal to those of passenger cars.

Rolling terrain is defined as a roadway on whichtrucks substantially reduce their speed belowpassenger cars on some sections.

Mountainous terrain is defined as a roadwaywhere trucks operate at crawls speeds for longdistances or frequent intervals.

Table 100.02Relation of Conditions to Design Levels of

Service

Conditions Design Levelsof Service

RURALFreeway Flat B

Rolling BMountainous C

Expressway Flat BRolling B

Mountainous CMajor Collector

Flat BRolling B

Mountainous CMinor Collector

Flat CRolling C

Mountainous DLocal Access Flat D

Rolling DMountainous D

URBANFreeway CExpressway CArterial (Main Rd) C-DFrontage Road DSector Road D

DIRECTIONAL RAMPS B-C

As an alternative to level of service D,consideration should be given to pairs of one-wayroads or alternative bypass routes to improve theLOS.

For an approximation of the number of lanesrequired on a multi-lane freeway or expressway,use the following design year peak hour trafficvolumes at the specified level of service:

Level of Traffic VolumeService (Average Vehicles)

Per Lane Per HourUrban C-E 1400-2000Rural C-D 1000-1200

The following sections deal with the generalcapacity calculations for various roadways. Sincethese calculation methods are lengthy and beyondthe scope of this document, the reader is referredto the Highway Capacity Manual (HCM), 1994.

104.01.01 Multi-lane Rural Roadway

The general equation for service volume of allmulti-lane roadways is given by:

SV = 2000 N (v/c) T Wwhere:

SV = Service volume (one direction) for agiven level of service

N = Number of lanes in each directionv/c = Service volume to capacity ratioT = Adjustment factor for trucks on gradesW = Adjustment for width and lateral

clearance

(See HCM Section 100.04.02)

104.01.02 Two Lane Roadways

Service volumes and capacities for two laneroadways are always both directions withoutregard to the distribution of volume by direction.

The general equation is given by:SV = 2000 (v/c) T W

where:SV = Service volume in vehicles per hour

(total both directions)v/c = Service volume to capacity ratioT = Adjustment factor for trucks on gradesW = Adjustment for width and lateral

clearance

(See HCM Section 100.04.02)


Part 2 100-5

104.01.03 Expressways

Expressways are analyzed using a series ofnomographs covering a range of average roadwayspeeds. The charts are based on 3.65 m lanes, fullwidth shoulders, and adequate clearances. (SeeHCM Section 100.04.02)

104.01.04 Expressway Ramps and WeavingSections

Capacities of urban expressways are influencedby entrance and exit volumes, weave distance,and the geometric layout. All of these factorsshould be considered in the capacity analysis.(See HCM Section 100.04.02)

104.01.05 Intersection Capacity

Intersections capacity generally governs thecapacity of the associated roadway. Signaltiming, intersection spacing, turning movement allplay a critical role in determining the overallcapacity. (See HCM Section 100.04.02)

105 CONTROL OF ACCESS

105.01 GENERAL

Control of access is achieved by limiting thenumber and location of roadway access points sothat the through traffic capacity or safety of thefacility will not be significantly impaired. Thereare three degrees of access control:

Full Access Control - Gives preference tothrough traffic by providing access only throughselected frontage/sector roads and by prohibitingat-grade crossings or direct access from abuttingproperty.

Partial Access Control - Still gives preference tothrough traffic but permits some at-gradecrossings and some private drivewayconnections.

Approach Road and Driveway Regulations -Without access control, abutting properties arepermitted access to the roadway, but the number,location and geometrics are regulated.

Table 100.03Control of Access by Road Type

Roadway Type Degree of Access ControlFreeway Full Access ControlExpressway Full or Partial Access ControlMajor Collector

Main Road Partial Access ControlMinor Arterial Approach RoadSector Road and DrivewayLocal Road Regulations

All Roadways will have some degree of accesscontrol. The appropriate degree of access controlby roadway type is given in Table 100.03. Moredetailed guidelines for establishing the control ofaccess lines by roadway classification arepresented in the following section.

105.02 ACCESS CONTROL DESIGNCRITERIA

105.02.01 Primary Roadways

The number of access openings on expresswayswith access control should be held to a minimum.Parcels which have access to another frontage orsector road as well as expressway frontage arenot allowed expressway access. In someinstances, parcels fronting only on theexpressway may be given access to anothersector road by constructing suitable connectionsif such access can be reasonably provided.

With the exception of extensive expresswayfrontages, access openings are limited to oneopening per parcel. Wherever possible, oneopening should serve two or more parcels. In thecase of a large expressway frontage under oneownership, the feasibility of limiting access toone opening may be prohibitive, or the propertymay be divided by a natural physical barrier suchas a wadi or ridge, making it necessary toprovide an additional opening. However, in thelatter case, it may be preferable to connect thephysically separated portions with a low-coststructure or road rather than permit twoopenings.

Access rights shall be acquired along interchangeramps to their junction with the nearest publicroad, and shall extend to the end of the ramp taper


Part 2 100-6

(or at least 50 m beyond the end of the curbreturn or ramp radius).

In remote areas, infrequent access should beaccommodated by providing locked gates. Thiswill only be considered for areas that are remote,infrequently used, and have no other accessmeans. Direct access will not be provided if itcreates an unsafe condition. Turning movementswill be limited to right turns only. Writtenapproval must be granted by the Abu DhabiRoad Section.

105.02.02 Secondary Roadways,ADT > 2500

In general, the number of access openings shall beheld to a minimum for any facility. Additionalaccess may be necessary to satisfy a range ofdesign issues/access requirements. The followingis a list of issues to consider when providingaccess points.

(1) Emergency vehicles shall have a right todirect roadway access.

(2) Private direct roadway access shall bepermitted only when the property in questionhas no other reasonable access to the localroad system.

(3) If feasible, parcels fronting only on theroadway shall be given access to anotherpublic road by constructing suitableconnections.

(4) Roadway access openings are limited to oneper parcel. Exceptions may be considered ifthey do not affect roadway safety oroperation and they are necessary for safe andefficient property use.

(5) In certain cases, a natural physical barriersuch as a wadi or ridge may divide the parcel.In this case additional access openings maybe warranted. However, it may be preferableto connect the physically separated portionsof the parcel with a low cost structure or roadrather than permit multiple access openings.

(6) Wherever possible, one access opening shouldserve two parcels.

(7) When the number of required access openingson one side of a divided roadway exceedsthree in 400 m, a frontage/sector road shall be

provided. See Section 105.03, Use ofFrontage Roads, for further discussions.

(8) Access openings on divided roadways shallnot be permitted within 100 m of a medianopening unless the access opening is directlyopposite the median opening.

(9) Access approaches shall be limited to rightturns only unless (1) the approach has nosignalization potential and allowing left turnswould significantly reduce congestion andsafety problems at a nearby intersection; or(2) there are no intersections, existing orplanned, that allow a U-turn; and (3) leftturns can be safety designed withoutsignalization.

(10) Access approaches with signalizationpotential and that require left turn movementsmust (1) meet the signalization requirementsas specified in Part 2, Section 902,Signalization, and (2) shall not interfere withthe location, planning, or operation of thegeneral road system and nearby propertyaccess.

105.02.03 Secondary Roadways,ADT < 2500

The primary function of these roadways is toprovide reasonable and safe access to abuttingproperty. Access needs generally take priorityover through traffic as long as roadway safety isnot compromised. Control of access is notobtained, but the location, number, andgeometry’s of access points must meet thefollowing criteria:

(a) The number of access approaches to a parcelshall be controlled by safety and designconsiderations and shall be separated by atleast the stopping sight distance.

(b) For safety reasons, frontage roads or parallelservice roads are not permitted along two-lane roadways because this results in theappearance of a divided roadway.

(c) Left turns if safety and design standards aremet.

(d) In rural areas, approach roads shall beprovided as necessary for local access oremergency/rest stops. The maximum spacing


Part 2 100-7

between approach roads shall be 5 km forthese purposes.

(e) In urban areas with signalized intersections,

the minimum spacing between access pointsshall be that which is necessary for the safeoperation and proper design of intersectionsas specified in Section 400.

105.03 USE OF FRONTAGE ROADS

(1) General Policy

(a) Frontage roads are provided:

• To control access to the urbanexpressway and main roadthrough lanes, thus increasingsafety.

• To provide access to sectors.

• Maintain continuity of the localroad systems.

• Provide for non-motorizedtraffic that might otherwisedesire to use the expressway.

(b) Typically a frontage road isjustified if their construction costsare less than the costs of providingother direct access. Right of wayconsiderations are often thedetermining factor. Thus, afrontage road would be justified ifthe investment in construction andextra right of way is less thaneither the severance damages orthe costs of acquiring the affectedproperty. Frontage roads may berequired to connect parts of asevered property or to serve alandlocked parcel resulting fromright of way acquisition.

(c) Direct access to the through lanesis allowable on expressways.However, when the number ofaccess openings on one side of theexpressway exceeds three in 500m, a frontage road should beprovided.

(2) New Alignment. Sector roads generallyare not provided on new expresswayalignments since the abutting propertyowners never had legal right of access tothe new facility. They may be provided,however, on the basis of considerationsmentioned above.

(3) Existing Alignment. Where an expresswayis developed parallel to an existingroadway or local road, all or part of theexisting roadway is often retained as afrontage or sector road. Frontage roadsmust be constructed to serve landlockedremainders or the remainders must bepurchased outright if other means ofaccess cannot be provided. The decisionwhether to provide access or purchaseshould be based on considerations of cost,right of way impacts, road systemcontinuity and similar factors discussedabove.

105.04 PROTECTION OF ACCESSRIGHTS

Access Control lines/limits shall be shown on theproject right-of-way plans. Where possible, theright-of-way line and control of access lineshould be coincident.

For proper control of access, fencing or otherapproved barriers shall be installed on allcontrolled access roadways, located on thecontrol or access line where appropriate.

106 DESIGN STANDARDEXCEPTIONS

A design standard exception is a design featurewhich does not meet the design standardspresented in the Roadway Design Manual.Occasionally these design exceptions are justifiedbut it is important that each design exception bedocumented and approved in writing prior to planacceptance.

The request for approval of design exceptionsshall be in the form of a Design ExceptionRequest. This request sheet shall be presented tothe Municipality for written approval. Therequest sheet shall include the following topics:


Part 2 100-8

• Proposed Project• Existing Roadway• Proposed Design Exception• Additional Cost To Comply With

Standards• Incremental Improvements• Supportive Data

A detailed description of the items required in theDesign Exception Request sheet is included on thefollowing pages.

DESIGN EXCEPTION REQUEST SHEET

1. PROPOSED PROJECT

A. Project Description: Briefly describe theproject. Note the type of project and/ormajor elements of work to be done, suchas safety or operational improvement,roadway widening, rehabilitation,reconstruction, etc. Provide thegeographic project limits and length.

B. Proposed Project Total Cost: Include aestimate of the proposed project costsegregated by major elements, including:roadway, structures, right of way, utilityrelocation, environmental mitigation, etc.,as needed.

2. EXISTING ROADWAY

A. Existing Roadway Description:Describe the existing roadway featuresrelevant to the proposed design exception.This may include such things as thewidths of lanes, shoulders, median, clearzones, roadbed, and structures;horizontal and vertical alignment andclearances; design speed, sight distance,grades, cross slope, superelevation, etc.

If relevant, provide a similar briefdescription of adjacent existing roadwaysegments, noting existing nonstandardfeatures.

3. PROPOSED DESIGN EXCEPTION

A. State the specific design standard(s)which are not being met and refer to their

Roadway Design Manual Part andSection number(s).

B. Describe the proposed design exception

or the existing design exception which isproposed to be maintained. If proposed,state whether the design exception is animprovement over the existing condition.Describe proposed improvements thatwould qualify as safety enhancementsover the existing condition, such as:median barrier, guardrail upgrade,flattening slopes, correctingsuperelevation, eliminating roadsideobstructions, etc.

C. Provide a thorough brief justification for

the design exception. Reasons forgranting design exceptions include acombination of excessive cost, right ofway impacts and/or environmentalimpacts. Supportive factors haveincluded low accident frequency, localopposition, and consistency with adjacentroadway segments.

4. ADDITIONAL COST TO COMPLYWITH STANDARDS

Provide a realistic estimate of the additionalcost required to meet the design standard forwhich the proposed exception is requested.

5. INCREMENTAL IMPROVEMENTS

Discuss other practical alternatives that areintermediate in scope and cost between theproposed project (requiring this designexception) and the full, standard solution.Provide enough information on costs versusbenefits, right of way and environmentalimpacts, etc., to explain why none of theincremental alternatives are recommended.These alternatives should normally beinvestigated prior to requesting an exception.

6. SUPPORTIVE DATA

A. Traffic Data: Provide both ADT’s andDHV (design hourly volumes). Usedesign year traffic.


Part 2 100-9

B. Accident Analysis: Safety is of primaryimportance when considering designexception approval. If relevant, includean accident data analysis to identifyprevalent accident types and causes, plusan evaluation of the effect of therequested design exception on accidenttypes and frequencies.

C. Attachments:

1. Provide a location or vicinity mapfor the project.

2. Provide plan sheets, cross sections,profiles and/or special details toclearly illustrate the proposeddesign exception.

3. Attach pertinent letters,resolutions, meeting minutes,studies, etc., which further developor clarify the proposed designexception.

107 BICYCLE FACILITIES

107.01 GENERAL

The bicycle has become an important element forconsideration in the highway design process.Fortunately, most of the mileage needed forbicycle travel is comprised of the street andhighway system. While many highway agenciesallow bicycles on partially access controlledfacilities, most highway agencies do not allowbicycles on fully access controlled facilities.

Measures such as the following, which aregenerally of low capital intensity, canconsiderably enhance a route’s safety andcapacity for bicycle traffic:

• Paved shoulders.• Wide outside traffic lane (4.2 m minimum) if

no shoulder.• Bicycle-safe drainage grates.• Adjusting manhole covers to the grade.• Maintaining a smooth, clean riding surface.

For further information and guidelines onbicycles, refer to the latest edition of AASHTO,Guide for Development of Bicycle Facilities.

107.02 SPECIAL BICYCLE FACILITIES

At certain locations or in certain corridors, it isappropriate to supplement further the existinghighway system by providing specificallydesignated bikeways (for either exclusive or non-exclusive bicycle use). Rural arterials often arethe only direct connection between areas ofpopulation and locations to which the publicwishes to travel, Schools, parks, and ruralhousing developments are usually located to bereadily accessible by automobile. However,pedestrians and bicycle riders may also wish totravel to the same destination points. When sucha situation exists, the designer should consider theeffects on the safety and operation of the arterial.A special effort should be made to provide thegreatest degree of safety within the economicconstraints that must always be considered.

107.03 BICYCLE CHARACTERISTICS

To provide for bicycle traffic, it is necessary tobecome familiar with bicycle dimensions,operating characteristics, and requirements.These factors determine acceptable turning radii,grades, and sight distance. In many instancesdesign features of separate bike facilities arecontrolled by the adjoining roadway, so that eventhen consideration of bicycles is an essentialelement the design of the highway itself.

107.04 BICYCLES ATINTERSECTIONS

When on-street bicycle lanes and/or off-streetbicycle paths enter an intersection, the design ofthe intersection should be modified accordingly.This may mean special sight distanceconsiderations, wider roadways to accommodateon-street lanes, special lane markings tochannelize and separate bicycles from rightturning vehicles, provisions for left turn bicyclemovements, or special traffic signal designs (suchas conveniently located push buttons at actuatedsignals or even separate signal indication forbicyclists).


Part 2 200-1

SECTION 200GEOMETRIC DESIGN

STANDARDS

201 SIGHT DISTANCE

201.01 GENERAL

Sight distance is the continuous length of roadwayahead visible to the driver. There are three distincttypes - passing, stopping, and decision. Passingsight distance is the minimum sight distancerequired by a driver to safely pass anothervehicle. Stopping sight distance is the distancerequired by a driver, traveling at a given speed, tostop after seeing an object on the road. At certainlocations decision sight distance is required toallow drivers extra time for making decisions.

201.02 PASSING SIGHT DISTANCE

Passing sight distance is the minimum sightdistance required by a driver to safely passanother vehicle. The sight distance available forpassing is the longest distance at which a driverwhose eyes are 1070 mm above the pavement cansee the top of a 1300 mm high object on the road.Passing must be accomplished without reducingthe speed of an oncoming vehicle traveling at thedesign speed. Table 200.01 lists sight distancestandards.

Passing sight distance is only considered on 2-lane roads and should be provided at frequentintervals. In general, minimum passing sightdistance should be provided for 60% of the routelength in level terrain, 40-60% in rolling terrainand 20-60% in mountainous terrain. Economicsshould be weighed against providing passing sightdistance or auxiliary passing lanes.

201.03 STOPPING SIGHT DISTANCE

Stopping sight distance is the distance required bya driver, traveling at a given speed, to stop aftersighting an object on the road. Stopping sightdistance is measured from the driver’s eyes, 1070mm above the road, to an object 150 mm high onthe road.

If providing passing sight distance is noteconomically feasible, stopping sight distance isthe minimum sight distance provided on multilaneand 2-lane roads. Stopping sight distance is theminimum provided for interchanges, at-gradeintersections and private road connections.

Table 200.01 shows the standards for sightdistance related to design speed.

Table 200.01Sight Distance Standards

Design Minimum Desired MinimumSpeed Stopping Stopping Passing

Sight (1) Sight (1) SightDistance Distance Distance

(kph) (m) (m) (m)

30 30 30 22040 45 45 28550 60 65 34560 75 85 41070 95 115 48580 115 140 54590 135 170 605100 160 205 670110 180 250 730120 205 290 795130 235 330 855

Minimum values shall be avoided in design,higher values are desirable.

(1) Increase by 20% on downgrades >3% & >2km. Values shown are for wet pavements.

Chapter III of “A Policy on Geometric Design ofHighways and Streets,” AASHTO, 1994,contains a thorough discussion of the derivationof stopping sight distance.

201.04 STOPPING SIGHT DISTANCEAT GRADE CRESTS

Figure 200.02 shows the relationship betweenvertical curve length, design speed, and algebraicdifference in grades. Any one factor can bedetermined when the other two are known.


Part 2 200-2

Figure 200.01Stopping Sight Distance on Crest Vertical Curves

Figure 200.02Stopping Sight Distance on Sag Vertical Curves


Part 2 200-3

201.05 STOPPING SIGHT DISTANCEAT GRADE SAGS

Stopping sight distance for grade sags isimportant at night when headlights need toilluminate the road ahead. Figure 200.02,provides the minimum sag vertical curve lengthwhich provides headlight sight for a given designspeed. Lighting may be considered as aneconomic option to lengthening the sag curve.

201.06 STOPPING SIGHT DISTANCEON HORIZONTAL CURVES

Figure 200.03 is used to determine the requiredclear distance (at a given design speed) from theinside lane centerline to a roadside obstruction.The driver’s eye is assumed 1070 mm above theinside lane centerline (inside with respect tocurve) and the object is 150 mm high. With littleor no vertical curvature, the sight line is assumedto intercept the obstruction at the midpoint of thesight line, 610 mm above the inside lanecenterline. The clear distance (m) is measuredfrom the inside lane center to the obstruction.

201.07 DECISION SIGHT DISTANCE

Decision sight distance is the distance required fora driver to detect an unexpected or difficult toperceive information source or hazard in aroadway environment that may be visuallycluttered, select an appropriate speed and path,and initiate and complete the required maneuversafely and efficiently. Decision sight distance isused at major decision points such as lane drops,changes in cross section, off-ramp noses tointerchanges, branch connections, roadside rests,vista points, and inspection stations. At theselocations, sight distance greater than stoppingsight distance is desirable to allow drivers timefor making decisions

The decision sight distances in Table 200.02provide appropriate decision sight distancerounded for design. Decision sight distance isbased on a 1070 mm eye height and a 150 mmobject height.

Table 200.02Decision Sight Distance

Design Decision Sight DistanceSpeed for Avoidance Maneuver (m)kph A B C D E

50 75 160 145 160 20060 95 205 175 205 23570 125 250 200 240 27580 155 300 230 275 31590 185 360 275 320 360

100 225 415 315 365 405110 265 455 335 390 435120 305 505 375 415 470

A Stop on rural road.B Stop on urban road.C Speed/path/direction change on rural road.D Speed/path/direction change on suburbanroad.E Speed/path/direction change on urban road.

From AASHTO, 1994, “A Policy on GeometricDesign of Highways and Streets”

202 SUPERELEVATION

202.01 GENERAL

As a vehicle travels a curved section of road it issubjected to centrifugal force which tends to pushit towards the outside of the curve. If the surfaceis flat, the vehicle is held in its curved path byside friction between the tires and pavement.Roadways are superelevated to further countercentrifugal force. Superelevation is the sloping ofthe roadway surface upward toward the outside ofthe curve. On a superelevated roadway,centrifugal force is resisted by the vehicle weightcomponent parallel to the superelevated surfaceand the tire side friction. However, it isimpractical to balance centrifugal force bysuperelevation alone, because for a given curveradius a certain superelevation rate is exactlycorrect at only one speed. At all other speeds sidethrust will either be toward or away from thecurve center. This thrust must be offset by sidefriction.


Part 2 200-4

Figure 200.03Stopping Sight Distance on Horizontal Curves

If the vehicle is not skidding, all forces are inequilibrium and are governed by the followingequation:

Centrifugal Factor = e + f = 0.0079V2 = V2

R 127RWhere:

e = Superelevation rate in m per memax = Maximum superelevation rate for

a given conditionf = Side friction factorR = Curve radius in mV = Velocity in kph

This equation is used to design superelevatedcurves for comfortable operation. Standardsuperelevation rates are designed to keep theportion of centrifugal force countered by tirefriction within allowable limits.

202.02 SUPERELEVATIONSTANDARDS

Maximum superelevation rates for variousroadway classifications are shown on Table200.03. Table 200.04 shows values for design

elements related to speed and horizontalcurvature.

Table 200.03Maximum Superelevation Rates

Roadway emax

ClassificationFreeways 0.06Expressways 0.06Ramps 0.06Main Roads and Collectors 0.04Sector Roads Normal Crown

202.03 CITY ROAD CONDITIONS

Lower superelevation rates may be necessary inurban areas where restricted speed zones orintersections are controlling factors. In addition,existing road grades, curbs, or drainage mayprove difficult to alter. Such conditions maywarrant, for example, a reduction in thesuperelevation rate, different rates for each half ofthe roadbed, or both. In warping road areas fordrainage, adverse superelevation should beavoided.


Part 2 200-5

Table 200.04Values for Design Elements Related to Speed and Horizontal Curvature

From AASHTO, 1994, “A Policy on Geometric Design of Highways and Streets”


Part 2 200-6

202.04 AXIS OF ROTATION

Aesthetics, grade distortion, superelevationtransitions, drainage, and driver perception shouldbe considered when selecting the axis of rotation.

Undivided Roadways - The axis of rotation shallbe at the roadway centerline. However, in specialcases changing the axis of rotation to the insidetravelled way edge can avoid drainage problemscaused by superelevation, or, improve curveperception for curves preceded by long relativelylevel tangents.

Expressway Connections and Ramps - The axisof rotation may be about either edge of travelledway or centerline if multinale. Appearance anddrainage considerations shall be considered whenselecting the axis of rotation.

Divided Roadways - The axis of rotation shall beat the median edge of each travelled way.However, for bridges with decked medians theaxis of rotation shall be at the centerline.

202.05 SUPERELEVATIONTRANSITION

General - Superelevation transition should bedesigned in accordance with Figure 200.04. Thelength of superelevation transition should bebased upon the combination of superelevation rateand width of rotation plane.

Edge of travelled way and shoulder profilesshould be plotted and irregularities and drainageproblems should be eliminated.

Superelevation Transitions - Roadwaysseparated by barrier or median will besuperelevated at independent rates. The transitionlength will be based on pavement width andsuperelevation change. The profile of the outsideedge of through pavement cannot differ from theprofile gradeline by more than the percentageshown on Table 200.04 and will be an unbrokenline throughout the transition. The minimumtransition length for a two lane roadway is shownon Table 200.04. For multiple lane roadways theminimum length shall increase proportionately.

An example of expressway superelevationdevelopment is shown on Figure 200.04.

For roadways on the inside of the curve, theoutside shoulder will begin rotating when theinside roadway pavement has reached asuperelevation of -3.0 percent (normal shoulderslope). When superelevation becomes greater than-3.0 percent, the pavement and shoulder willrotate in unison.

The location of a superelevation transition, withrespect to the point of curvature, will bedetermined using the inside roadway transition.Approximately one-third of the transition lengthwill be placed on the curve. The remainingtransition length will be on the tangent. Thetransition location will be adjusted to begin/end ata 10 meter station.

For roadways on the outside of the curve, thetransition will begin/end at the adjust the curvedetermined by the inside roadway transition. Anadditional transition length is required to rotatethe outside shoulder from -3.0 percent (normalshoulder slope) to -1.5 percent (normal pavementslope). This shoulder transition length must beadded to the pavement transition length to get thetotal transition length.

Restrictive Areas - In restrictive areas, wherefull superelevation cannot be achieved, the highestpossible superelevation rate and transition lengthshall be used. But, in no case shall the cross sloperate of change exceed 4% per 20 m.

Superelevation Transitions on Bridges -Superelevation transitions on bridges should beavoided.

202.06 SUPERELEVATION OFCOMPOUND CURVES

Compound curve superelevation shall be perFigure 200.05. Where feasible, the criteria inSection 202.05 shall apply.


Part 2 200-7

Figure 200.04Freeway/Expressway Superelevation Transitions


Part 2 200-8

Figure 200.05Superelevation Transitions for Compound Curves


Part 2 200-9

203 HORIZONTAL ALIGNMENT

203.01 GENERAL

Horizontal alignment consists of a series ofcircular curves and tangent sections. Thehorizontal alignment should provide safecontinuous uniform operation for substantialroadway lengths. The major factors influencinghorizontal alignment design are safety, profile,type of facility, design speed, cost, geotechnicalconstraints, topography, aesthetics, andfunctionality. All of these factors must bebalanced to produce the safest, most economicalalignment, which is in harmony with the naturalcontour of the land, and at the same time adequatefor the design classification of the roadway.

In design, safety is always a major factor. Thehorizontal alignment shall provide at least theminimum stopping sight distance for the chosendesign speed at all points along the roadway. Thefollowing standards apply to horizontal curvatureon both 2-lane and multilane roadways except asnoted.

203.02 STANDARDS FORHORIZONTAL CURVATURE

Minimum Curvature - Table 200.05 gives theminimum curve radius based on design speed.

Table 200.05Standards For Curve Radius

Roadway MinimumClassification Curve Radius (m)

RURALFreeway 2000Expressway 2000Collector 600Local Access 100

URBANFreeway 600Expressway 600Arterial (Main Rd) 600Frontage Road 600Sector Road 100

LOOP RAMPS 45This table assumes unlimited sight distance.Minimum radius should also be checked againstFigure 200.03. Every effort should be made toexceed the minimum.

If a glare screen or median barrier is used,adjustments may be necessary to maintain therequired sight distance on divided roadwaycurves.

Alignment Consistency - Sudden reductions inalignment standards shall be avoided.Introduction of curves with lower design speedsshall be avoided at the end of long tangents, steepdowngrades, or at other locations where highapproach speeds may be anticipated. In no caseshall the design speed between successive curveschange more than 15 kph.

On roadways in mountainous or rolling terrainwhere horizontal and vertical curves aresuperimposed at grade summit or sag, the designspeed of the horizontal curve should be at leastequal to that of the crest or sag, and not morethan 15 kph less than the measured or estimatedrunning (85th percentile) speed of vehicles on theapproach roadway.

Curve Length and Central Angle - For centralangles less than 10 degrees, the minimum curvelength should be 240 m to avoid a kinkedappearance. For central angles smaller than 30minutes, no curve is required. Above a 6000 mradius, parabolic curves may be used. In no caseshall sight distance or other safety considerationsbe sacrificed to meet the above requirements.

Lane curve lengths in excess of 800m on 2-laneroadways should be avoided in consideration ofthe safety aspects associated with driverattentiveness and oncoming headlight glare.

On 2-lane roads a curve should not exceed alength of 800 m.

Compound Curves - Compound curves shall beavoided, except where use of a simple curveresults in excessive cost.

If compound curves are used, the shorter radiusshould be at least two-thirds the longer radiuswhen the shorter radius is 300 m or less. The totalarc length of a compound curve should not be lessthan 150 m.


Part 2 200-10

Reverse Curves - When horizontal curvesreverse direction the connecting tangents shall belong enough to accommodate the standardsuperelevation runoffs given on Figure 200.04. Inno case shall the cross slope rate of changeexceed 4% per 20 m.

Broken Back Curves - A broken back curveconsists of two curves in the same direction joinedby a short tangent section. Broken back curvesare unsightly, undesirable and should be avoided.

Alignment at Bridges - If possible, a bridgeshould be located entirely on a tangent or curvebecause superelevation transitions on bridgesalmost always result in unsightly bridge andbridge railing appearance. However, alignmentand safety considerations shall govern.

Intersections and Interchanges - If possible,intersections should be on tangent sections or flathorizontal curves with very little superelevation.

Interchanges, such as a typical diamondinterchange, include two closely spaced at-gradeintersections that function inter-dependently. Atangent alignment should be maintained betweenintersections for signal visibility and laneassignment determinations required by themotorist.

204 VERTICAL ALIGNMENT

204.01 GENERAL

Vertical alignment consists of a series of gradesconnected by parabolic vertical curves. It is usedto establish elevations for all roadway features. Itis controlled mainly by topography, roadwayclass, horizontal alignment, safety, sight distance,costs, cultural development, drainage, andaesthetics. Steep grades affect truck speeds andoverall capacity.

All portions of the vertical alignment shall meetminimum sight distance requirements.

204.02 VERTICAL ALIGNMENTPOSITION WITH RESPECT TOCROSS SECTION

The grade line should generally coincide with theaxis of rotation for superelevation. Its relation tothe cross section should be as follows:

Undivided Roadways - The grade line shouldcoincide with the roadway centerline.

Expressway Connections and Ramps - Thegrade line may be positioned at either edge oftravelled way or centerline if multilane.

Divided Roadways - The grade line may bepositioned at either the median centerline or at theultimate median edge of travelled way. Theformer case is appropriate for paved medians 9 mwide or less. The latter case is appropriate when:

a) The median edges of travelled way of thetwo roadways are at equal elevation.

b) The roadways are at different elevations.c) The median width is ununiform.

204.03 STANDARDS FOR GRADES

Maximum Grades - Table 200.06 lists themaximum grades for design for rural roadwaysbased on design speed and urban roadways basedon roadway type.

Minimum Grades - The desirable minimumgrades should be not less than 0.3 percent forcurbed pavement sections and 0.2 percent in veryflat terrain. Minimum grades can be maintainedin very flat terrain by use of a rolling profile.

In developed urban areas with extremely flatterrain, flatter minimum grades may be warrantedin consideration of adjacent building elevationsand offsite drainage problems associated withrolling profiles. The use of minimum gradesflatter than those specified above will require caseby case approval by the Road Section.


Part 2 200-11

Table 200.06Grade Standards

RuralDesign Level Rolling MountainousSpeed(kph) % % %

60 5 6 870 5 6 780 4 5 790 4 5 6

100 3 4 6110 3 4 5120 3 4 5130 3 4 4

Urban Desirable AbsoluteRoadway Maximum Maximum

Type % %

Freeway 3 4Expressway 3 4Ramps 4 6Arterial (Main Rd) 2 3Frontage Road 2 3Sector Roads 2 3

204.04 VERTICAL CURVES

Parabolic vertical curves are used in roadwaydesign per Figure 200.06.

Figures 200.07 and 200.08 will be used to obtainvertical curves lengths. For design speeds greaterthan 65 kph, the minimum vertical curve lengthshould be 120 m. For 50 kph design speed, itshould be 60 m.

Flat vertical curves may develop poor drainage inthe level section. Adjusting the edge grade orshortening the vertical curve may be required.

Design of these long vertical curves should beavoided because many drivers will not pass oncurves over 1 km long, despite adequate sightdistance. It may be more economical to constructpassing lanes than to obtain passing sight distanceby using a long vertical curve.

204.05 LONG SUSTAINED GRADES

The maximum grade guideline is not sufficient toinsure uniform roadway operation. The uphill

grade length must be considered because it has amajor effect on operational speed, capacity, levelof service, and contributes to heavy truck delays.Figure 200.09 shows the speed reduction in kphfor an assumed typical heavy truck of 180 kg/kWas a function of grade length and upgrade percent.Generally, a truck speed reduction of up to 15kph does not significantly impact roadwaycapacity.

Consideration should be given to adding laneswhere the truck speed reduction is greater than 15kph and there is a significant reduction in level-of-service when moving from the approachsegment to the grade. On two lane roadways, aclimbing lane should be considered when, inaddition to the above criteria, the upgrade trafficflow is in excess of 200 vehicles per hour and thetruck factor is in excess of ten percent. Decisionsight distance should be provided at climbing lanedrops on expressways.

204.06 STRUCTURE GRADE LINE

Structure Depth - The depth to span ratio for astructure is dependent on many factors. Use astructure depth to span ratio of 0.04 to 0.045 forpreliminary design purposes.

Falsework Allowance - To establish the grade ofa structure constructed with a falsework opening,allowance must be made for the falsework depth.The minimum vertical falsework clearance overprimary and secondary roadways shall be 4.8 m.The minimum vertical falsework clearance overlocal roadways shall be 4.5 m.

Bridge Deck Drainage - Vertical alignmentdesign requires special consideration of structuredrainage. Zero gradients and sag vertical curvesshould be avoided on bridges. Parapets collectlarge amounts of debris and smaller bridge deckdrains or scuppers have a higher potential forclogging. The minimum desirable longitudinalslope for bridge deck drainage is 0.2 percent.Where vertical curves on bridges cannot beavoided, the elevations should be checked toprovide a minimum effective longitudinal grade of0.5 percent, and not extend more than 15 m eitherside of the sag or crest point.


Part 2 200-12

Figure 200.06Symmetric Parabolic Vertical Curves


Part 2 200-13

Figure 200.07Design Controls for Crest Vertical Curves, for Stopping Sight Distance- Upper Range.

From AASHTO, 1994, “A Policy on Geometric Design of Highways and Streets”.


Part 2 200-14

Figure 200.08Design Controls for Sag Vertical Curves - Upper Range.

From AASHTO, 1994, “A Policy on Geometric Design of Highways and Streets”.


Part 2 200-15

Figure 200.09Critical Lengths of Grade for Design, Assumed Typical Heavy Truck of 180 kg/kW,

Entering Speed 90 kph.From AASHTO, 1994, “A Policy on Geometric Design of Highways and Streets”.


Part 2 200-16

204.07 SEPARATE PROFILE GRADELINES

Separate grade lines should be considered for alldivided roadways. The use of separate grade linesprovides the opportunity to optimize the verticalalignment, drainage features, and provide a safermore economical design.

They are not normally considered appropriatewhere medians are less than 18 m wide.Exceptions to this may be minor differencesbetween opposing grade lines in specialsituations.

In addition, for either interim or ultimateexpressways, any appreciable grade differentialbetween roadbeds should be avoided in thevicinity of at-grade intersections. For trafficentering from the crossroad, confusion andwrong-way movements could result if thepavement of the far roadway is obscured becauseof excessive differential.

205 COORDINATION OFHORIZONTAL AND VERTICALALIGNMENTS

The coordination, of horizontal and verticalalignments is based on experience and engineeringjudgment. Successful coordination is essential fora safe well balanced design. The following areguidelines to be used, where possible.

• Vertical curves should be superimposed onhorizontal curves. This reduces the number ofsight restrictions, makes profile changes lessapparent, and results in a pleasingappearance. However, when superimposed,the superelevation and profile gradecombination may distort the outer pavementedges, confusing drivers at night. In suchsituations edge of pavement profiles shouldbe plotted and smooth curves introduced toeliminate distortion.

• Avoid sharp horizontal curvature at or nearthe top of a crest vertical curve. Thiscondition makes it difficult for the driver toperceive the curve, especially at night whenheadlights do not illuminate the curve.

• Avoid sharp horizontal curvature at or nearthe low point of a sag vertical curve.Foreshortening of the horizontal curve and

high approach speeds may result in erraticoperation, especially at night.

• For moderate changes in horizontal alignmentat grade summits, the horizontal curve shouldoverlap the vertical curve.

• Avoid successive changes in profile which arenot associated with horizontal curves. Thesuccession of humps is unattractive.

• Horizontal and vertical curvature atintersections should be as flat as physicalconditions permit.

• Avoid excessive curvature to obtain flatgrades and tangent alignment or flat curves atthe expense of steep or long grades. It isbetter to balance horizontal and verticalalignments.

• In general, alignments should be designed totake full advantage of scenic opportunities.

206 PAVEMENT TRANSITIONS

206.01 GENERAL

A pavement transition occurs when changingfrom one roadway cross section to another. Iffeasible, the transition should occur on a tangentsection. And be entirely visible to the driver.Avoid locations with sight distance restrictions.Transitions should not occur within at-gradeintersections. Decision sight distance shall beprovided at all lane drops.

206.02 TRANSITIONS FORMULTILANE ROADWAYS

Four Lanes to Two Lanes - A typical transitionbetween 4 lanes and 2 lanes is shown in Figure200.10. The alignment and the unspecified radiusof curvature varies depending on median widthand other site considerations.

Lane Drop - The minimum taper length for alane drop should be equal to 0.6WV, where W =Dropped Lane Width (m), and V = Design Speed(kph). The transition should be on the right sothat traffic merges left.

Lane Addition - The minimum taper rate to adda lane should be 25:1 but in no case shall thetaper length be less than 50 m.


Part 2 200-17

Figure 200.10Typical Two-Lane to Four Lane Transitions


Part 2 200-18

207 BRIDGES AND GRADESEPARATION STRUCTURES

207.01 CLEAR WIDTH

The clear curb to curb width of all bridges orgrade separation structures shall equal the sum ofthe full travelled way approach width, pavedshoulders and barrier offset (if any).

207.02 CROSS SLOPE

The cross slope shall be the same as the approachpavement. The crown is normally centered on thebridge except for one-way roadways where astraight crosslope in one direction should be used.

207.03 SIDEWALKS

Sidewalks should be provided where justified bypedestrian traffic or if the approach roadway hassidewalk. The sidewalk width should match theapproach sidewalk width and crosslope.

208 PEDESTRIAN FACILITIES

208.01 SIDEWALKS

Sidewalk widths and locations vary but they shallhave a minimum width of 2.0 m and be located toprovide continuity in pedestrian movement.

Pedestrian crosswalk ramps shall be located at allintersections and all other locations where mainpedestrian traffic crosses curblines.

Cross Slope - The minimum sidewalk cross slopeshould be 1.5% toward the roadway.

Sidewalk Widths - The guidelines in Table200.07 should be used to determine sidewalkwidth.

Table 200.07Sidewalk Width Guidelines

Area/ vicinity Width (m)Multi Family Units/Schools/

Office/Industrial 2.0Shopping/Recreation/Bus/Taxi 4.0

The minimum sidewalk width shall be 2.0 m.

208.02 PEDESTRIAN GRADESEPARATIONS

Pedestrian grade separations are not normallyprovided on roadways. However, if pedestrian useis extensive, an overcrossing or undercrossingmay be considered. Justification for pedestriangrade separation structures comes from thedetailed study of present and future communityneeds. Each situation should be studied separatelyand the study should include pedestriangenerating sources, travel patterns, crossingvolumes, roadway classification,location/circuitry of adjacent crossings, land uses,sociological and cultural factors, and thepredominant type and age of users.

Established pedestrian patterns should bemaintained across expressway routes. Separatepedestrian structures should be provided ifvehicular crossings are inadequate forpedestrians. If a circuitous route is involved, apedestrian separation may be justified. Specialconsideration should be given to school crossings.

The choice between an undercrossing or anovercrossing should be based on relative costs,groundwater influence, drainage, existing utilities,current and future land use, visibility, topographyand the surrounding architecture.

208.03 PEDESTRIAN UNDERPASSES

Undercrossings require special consideration,visibility issues and the potential for criminalincidents and vandalism. If an undercrossing isused, unobstructed visibility shall be providedthrough the structure and approaches. The desiredvertical clearance is 3.0 m, but in no case shallthe clearance be less than 2.0 m. The minimumwidth shall be 2.5 m.

209 CURBS

209.01 GENERAL

Curbs will be provided along all edges ofpavement in urban areas. Reasons for providingCurbs include:


Part 2 200-19

• Required for proper drainage.• Needed for channelization, delineation,

control of access, or improving traffic flowand safety.

• To protect pedestrians and provide continuityat ramp connections with local roads.

• To replace existing curbs.• To protect the expressway fence on frontage

roads where required.

209.02 TYPES AND USES

Curb types and uses are shown in the currentStandard Drawings and are discussed below.

Precast Curb Type A, B, C - These curbs areused to deter vehicles from using areas outside thetravelled way, control drainage, and regulate andcontrol parking. Type A curbs are typically usedon the outside of the travelled way, adjacent tosidewalks and parking lanes. Typical B and Ccurbs are used at the median edge adjacent to thegreen area.

The above curb types are classified as barriercurbs and are not generally used on high-speedroadways as they present a safety hazard forerrant vehicles. A continuous concrete barrier(safety shape) should be used where it isnecessary to control drainage or access on high-speed roadways.

Cast-In-Situ Concrete Curb Type D - This curbis flush with the pavement and used to separatethe travelled way from interlocking vehicularpavement.

Precast Concrete Curb Type E - This curb isused between interlocking pedestrian pavers andgreen or service reservation areas.

Cast-In-Situ Concrete Curb Type F - This curbis flush with the pavement and used to separateinterlocking pedestrian pavers from quarry tile.

209.03 CURB PARAMETERS

Placement - Curbs should be positioned toprovide the same unobstructed roadway widththat is normally provided. All curb dimensions areto the inside face of curb.

Transitions - A transition from one curb type toanother shall be done in 3.0 m. At curb termini,the curb should transition from normal curbheight to zero in 5.0 m.

210 BUS STOPS AND TAXI STOPS

In urban areas, bus stops and taxi stops will beprovided on all main roads.

To prevent ponding in bus and taxi stops on flatgrades use either a reverse cross slope toward themain road pavement with slotted trench drains orcontinue the slope of the roadway and install aninlet along the loading/unloading curb line.

210.01 BUS STOPS

Bus stops will be located at the far side ofintersections and as necessary at midblocklocations. Near side bus stops should be avoided.

Normally, bus stops shall be constructed asshown on the current Standard Drawings. Underrestrictive conditions these standards may bereduced to 15.0 m length, 10.0 m tapers and 3.25m width.

At all bus stops a 4.0 m wide sidewalk shall beprovided along the loading/unloading area. Thisshall be connected to the nearest sidewalk with a4.0 m wide perpendicular sidewalk.

210.02 TAXI STOPS

Taxi stops will be located at the far side ofintersections, no closer than 30.0 m to the radiusreturn or end of right turn taper. Taxi stopsshould be located as necessary within the blockbut no closer than 30.0 m to a sector road.

Taxi stops shall be constructed as shown on thecurrent Standard Drawings. At all taxi stops a 4.0m wide sidewalk shall be provided along theloading/unloading area. This shall be connected tothe nearest sidewalk with a 4.0 m wideperpendicular sidewalk.


Part 2 200-20

211 PARKING

To maximize the effective capacity of expresswayand main road improvements, sufficient off-system parking facilities should be provided toavoid the need for curb lane parking alongprimary expressways and main roads.

211.01 GENERAL

Parking facilities are of four general types:

1. Parking areas located parallel to, butphysically separated from, main roadmoving traffic lanes,

2. On-road parking spaces developedadjacent to the travelled lanes of sectorroads, and

3. Independent parking lots developed offsector roads.

4. Parking Structures.

Each facility consists of an “aisle” area and a“standing area” (parking stalls). In the case of on-road parking, the moving lanes of the sector roadalso serve as the aisle.

Figure 200.11 illustrates different forms of thebasic types of parking facilities.

211.02 PARKING AREAS

Lots P1 and P2 on Figure 200.11 are typical“parking areas,” characterized by one entranceoff the main road, then an aisle area with adjacentperpendicular and/or 45 degree parking, andfinally an exit leading back onto the main roadtravel lanes. Desirably, the entrances and exitsshould be independent of any sector road or mainroad intersections (i.e., Lot P2). When physicalconditions prevent this, a common entrance (orexit) may be an acceptable arrangement (i.e., LotP1).

The minimum safe distance from a main roadintersection to a parking entrance or exit will bedependent on many factors, such as, volume andspeed of the traffic, type of intersection, widthand number of lanes in the main road, the volumeof traffic using the parking area, and any sightdistance restrictions.

Generally it is desirable to locate parking exitsonto main roads about 50 meters prior to the startof the left turn storage lane, and parking entrancesoff of main roads about 60 meters prior to theintersection, and/or prior to the start of the freeright turn taper.

In the typical case, a “parking area” is physicallyseparated from the main road lanes by acurb/sidewalk/curb combination which has beendesignated as a “wide curb”. See Lot P2 in Figure200.11. The minimum distance between the facesof the two curbs is 1.0 m.

The parking area edge nearest the buildingsshould be set parallel to the building line and at asufficient offset distance to allow a sidewalkalong the building line.

The current Standard Drawings illustrate typicalparking area and show stall dimensions andpavement markings for both perpendicular and45-degree parking arrangements. Aisle widths andstall depths should be as per Table 200.08.

Table 200.08Parking Isles and Stall Depths

Parking Aisle Width Stall DepthAngle (m) (m)

Absolute Desirable Absolute DesirableMin Min Min Min

90o 7.0 7.3 5.5 5.860o 5.0 5.5 5.7 6.045o 4.5 5.0 5.3 5.6

211.03 ON ROAD PARKING SPACES

Parking spaces along sector roads are developedby constructing added pavements immediatelyadjacent to the sector road moving lanes (usuallytwo lanes with one lane for travel in eachdirection). Such parking spaces should be eitherparallel or perpendicular. The use of 45-degreeparking should be limited to one-way sectorroads.

Figure 200.11 shows examples of on-roadparking space developments along sector roads.Dimensions for perpendicular and 45-degree


Part 2 200-21

parking stalls are similar to those given on theStandard Drawings.

Parallel parking stalls should have a length of 7.0m and a desirable minimum width of 2.5 m asshown on the Standard Drawings.

Where sector roads are widened to provideparking stalls, the widened sector roadarrangement should not be carried through sectorroad/sector road intersections. The fillets at suchintersections (usually 5.0 m radii) should bepositioned to line up with the edge of the travelledlanes.

211.04 PARKING LOTS

Figure 200.11 also shows samples of independentparking lots developed off sector roads. Such lotsare of two general varieties:

1. Single entrance/exit (see lots P3, P4 and P5)and

2. Double entrance/exit (see Lots P6 and P7).

Wherever practical, these layout rules should befollowed:

1. Aisles and entrance/exit widths should betypically designed for two-way operation inconjunction with perpendicular parking.

2. A median (curb/sidewalk/curb combination)at least 1.0 m wide should be providedbetween adjacent parking bays served offdifferent aisles (i.e., on Figure 200.11, abarrier is provided between Lots P6 and P7).

3. Forty-five degree parking should only be usedin conjunction with one-way aisles/sectorroads.

211.05 PARKING DEMAND/SUPPLYANALYSIS

During the early portion of the Concept DesignPhase, the designer will:

1. determine the location of existing parkingfacilities,

2. identify any facilities to be displaced by roadimprovements that should thus be replaced,and

3. determine the need for added parking facilitiesand establish an approximate location forsuch parking.

The required analysis regarding parking will thusvary from project to project since parking demandis sensitive to site-specific factors, such as landuse and proposed community developments.

In the absence of site specific parking criteria,Table 200.09 should be used. Also refer to Part 1,Section 202.02.11 for further parkingrequirements.

Table 200.09Parking Requirements

Type of Development ParkingRequirements

Commercial/Office 1 space / 50 m2 floorspaceRetail 1 space / 30-50 m2 floorspaceGovernmental 1 space / 50 m2 floorspaceSchool 1 space / 3 employeesplus

1 space / 5 studentsHospital 1 space / 2 employeesplus

1 space / 4 bedsLow Density

Residential Villas 2 spaces / dwelling unitMedium Density

Apartments 1 space / (100m2*.85*.80)

High DensityApartments 1 space / (100m2*.85*.80)

These requirements should be considered asminimums.

It is possible that the number of spaces requiredby these guidelines cannot be provided due tospace limitations. In that case, efforts should bedirected toward providing the maximum amountof parking in a reasonable configuration.


Part 2 200-22

Figure 200.11Typical Parking Facilities


Part 2 300-1

SECTION 300GEOMETRIC CROSS SECTION

301 TRAVELLED WAY STANDARDS

301.01 TRAVELLED WAY WIDTH

Travelled way width is one of the most importantsafety factors in design. A wide two-lane two-waypavements provides higher capacity, higher drivercomfort levels, consistent operation and loweraccident rates.

Minimum travelled way widths of 7.30 m shall beprovided on all design classes of roadways.Traffic lane widths shall be 3.65 m, and thenumber of lanes required shall be based on theprojected traffic volume and roadwayclassifications. Loop ramp lanes shall be 5.0 m.

See Section 302 for general shoulder widths andsee Section 305 for specific roadway crosssection widths.

301.02 TRAVELLED WAY CROSSSLOPES

Tangent cross slope is balanced between steepcross slopes, desirable for drainage and the factthat vehicles drift toward the lower pavementedge on steep cross slopes. Generally, crossslopes below 1.5 percent have little effect onvehicle steering. Cross slope values for thevarious roadway classifications are provided inthe following sections.

Unpaved travelled ways shall have a cross slopeof 3.0 percent.

See Section 305 for specific roadway cross sloperates.

Pavement superelevation on curves shall be asdetermined in Section 202.

302 SHOULDER STANDARDS

Shoulders provide pavement structural support,improve sight distance, provide emergencystopping areas, and help provide required sideclearance. However, shoulders are unnecessary on

most urban roads because curbs providepavement structural support, and disabledvehicles can park in parking lanes, side streets, ordriveways.

302.01 SHOULDER WIDTHSTANDARDS

Table 300.01 summarizes the minimumcontinuous usable width of paved shoulder forvarious roadway classifications.

Table 300.01Paved Shoulder Width Standards

Roadway Inside OutsideClass Shoulder Shoulder

/ verge / verge(m) (m)

RURALFreeway 3.0 4.0/2.0Expressway 3.0 4.0/2.0Collector - 2.4Local Access 2.0

URBANFreeway 3.0 4.0/2.0Expressway 3.0 4.0/2.0Arterial (Main Rd) - 4.0/2.0Frontage Road 1.2 1.2Sector Road - -

2-LANE RAMP 2.4/2.0 3.0/2.0LOOP RAMP 2.0/1.0 3.0/1.0

The verge is the area outside the paved shoulder,usually rounded, at the top of embankmentslopes.

302.02 SHOULDER CROSS SLOPES

In normal tangent sections, inside shoulder slopeshall match the travel lanes and outside shouldersshall slope on a 3% grade away from the travelledway.

303 SIDE SLOPE STANDARDS

Properly designed side slopes insure roadwaystability and provide a safe recovery area forerrant vehicles.

Where feasible, slopes should be flattened to beconsistent with the roadway classification andtopography. The tops and ends of all slopes


Part 2 300-2

should be rounded 3.0 m where the material isother than solid rock.

303.01 SIDE SLOPE VALUES

Side slopes should be 1:6 or flatter depending onsoil type. If slopes are steeper than 1:3, barriermay be required. Earth cut slopes should be atleast 1:3 but in no case steeper than 1:2.

303.02 SLOPE CLEARANCE FROMRIGHT OF WAY

The minimum clearance from the right of way lineto the catch point should be 3.0 m with 4.5 mdesired. For cut slopes this is measured from theouter edge of the rounding or crown drainagesystem. Slopes over 15.0 m high may requireadditional clearance for maintenance.

304 MEDIAN STANDARDS

A median is the portion of a divided roadwaybetween the opposing travelled pavements.

Raised medians shall be used on urban roads toregulate left-turn movements. Paved medians,including those bordered by curbs, should becrowned at the center, sloping towards the sides atthe slope of the adjacent pavement.

Unpaved, landscaped medians between curbsshall be graded flat. Other unpaved mediansshould slope downward from the shoulders toform a shallow valley. Cross slopes should be1:10 or flatter 1:20 being preferred. Slopes assteep as 1:6 are acceptable if necessary fordrainage.

See Section 305 for specific roadway medianrequirements.

305 CROSS SECTION ELEMENTS

See Figure 300.01 for typical cross sections ofvarious roadway classifications.

Pavement Structure - For the StandardPavement Structures, see current StandardDrawings. Also, refer to Section 604 StructuralPavement Section Design.

Shoulders - Shoulder widths for various roadwayclassifications are summarized in Table 300.01.

305.01 RURAL FREEWAY/EXPRESSWAY CROSSSECTION

General - The typical section for ruralexpressways shall be comprised of two roadwayswith shoulders, divided by a median.

Travelled Roadways - Each roadway willconsist of a minimum of three 3.65 m throughlanes. Ramps shall be 5.0 m for one lane and,where volumes demand, two 3.65 m lanes.

Median - Median treatment may be eitherstandard concrete barriers placed along the insideshoulder edge or an unpaved depressed median.Median width may vary to match existing medianwidths. The width of the depressed medianmeasured between edges of travelled pavementshall be 20.0 m minimum.

Cross Slope - Except superelevated sections, auniform cross slope of 1.5 percent shall beapplied across the inside shoulder and drivinglanes. The outside shoulder will have a cross-slope of 3.0 percent. The pavement will slopetoward the outside of the section.

On structures, the cross-slope shall be 1.5 percentuniformly across the inside shoulder, drivinglanes, and outside shoulder.

Profile Grade Line - The profile grade line shallbe at the median edge of the travelled roadway.

305.02 URBAN FREEWAY/EXPRESSWAY CROSSSECTION

General - The typical section for urbanexpressways shall be comprised of two roadways,with shoulders, divided by a median. Due to spacelimitations, the cross section may vary. The finalconfiguration shall be determined during theconcept phase of design.


Part 2 300-3

Figure 300.01Typical Cross Sections


Part 2 300-4

Travelled Roadways - Each roadway willconsist of a minimum of three 3.65 m widethrough lanes. Ramps shall be one 5.0 m lane,and where volumes demand, two 3.65 m lanes.

Median - A minimum 7.0 m wide median shall beused. However, a 10.0 m median width isdesirable. The median may be either unpaved anddepressed (if 20.0 m wide or more), or it mayhave concrete barriers.

Cross Slope - Except in superelevated sections, auniform cross slope of 1.5 percent shall beapplied across the inside shoulder and drivinglanes. The outside shoulder will have a crossslope of 3.0 percent. The pavement will slopetoward the outside of the section.

On structures, the cross slope shall be 1.5 percentuniformly across the inside shoulder, drivinglanes, and outside shoulder.

Profile Grade Line - The profile grade line shallbe the median edge of the travelled roadway.

305.03 ARTERIAL (MAIN ROAD)CROSS SECTION

The standard cross section of roadways iscomprised of two unidirectional pavements,median, sidewalks, service reservations and greenareas.

Pavement and Lane Widths - The pavement willconsist of a minimum of three traffic lanes in eachdirection divided by a raised median. Wherevernecessary, auxiliary lanes shall be provided forturning movements. Auxiliary lanes, whetherallocated to through traffic or to turningmovements, shall be 3.65 m wide.

Free Right Turn Islands and Lanes - Exclusiveright-turn lanes and islands shall be usedwherever possible. No more than one exclusiveright-turn lane shall be provided in any direction.

Left Turn Lanes - Unless otherwise approved bythe Municipality Road Section under specialconditions, no more than one left-turn lane shallbe provided from the median.

Parking, Loading/Unloading Lanes - Except fortaxi stops and bus stops, no parking orloading/unloading spaces shall be provided onmain roads without being separated from thetraffic lanes by a wide curb.

Median - A median with 22 cm high curbs shallbe provided. The median width should be at least5.0 m. Where an existing street with a median ofless than 5.0 m is being upgraded, the medianshould be increased to 5.0 m if possible. Wherean existing street with a median width of greaterthan 5.0 m is being upgraded, the existing medianwidth should be maintained for planting. Medianwidth shall be reduced to permit exclusive left-turn lanes at intersections where required.

No provision shall be made for U-turns except atintersections.

Curbs - Curbs shall be provided along all edgesof pavement in urban areas. Curb types and usesare shown in the current Standard Drawings.

Sidewalks - Sidewalk widths and locations willvary but the minimum width shall be 2.0 m andthey shall be located to provide pedestrianmovement continuity. In addition, wheneverpossible a 2.0 m wide sidewalk adjacent to thepavement and green areas should be providedprimarily for aesthetic purposes.

Pedestrian crosswalk ramps shall be used at allintersections and all other locations where themain pedestrian sidewalk crosses curb lines.

Cross Slope - All pavement will have a brokencross-slope of 1.25 percent sloping away from themedian across the two inside lanes and 2.0percent for the outside lanes. A 1.5 percent cross-slope shall be provided toward the pavement onsidewalks. Cross-slope will vary at intersectionsin accordance with current Standard Drawings.

Profile Grade Line - The profile grade line shallbe the median edge of pavement.


Part 2 300-5

305.04 SECTOR ROAD CROSSSECTION

The cross section for sector roads will consist ofan undivided two-directional roadway. Curbsshall be provided along both edges of pavement.

Pavement and Lane Widths - Lane width shallbe 3.65 m for two lanes in each direction and 4.0to 5.0 m for one lane in each direction.

Free Right Turn Islands and Lanes - No freeright turn islands or lanes shall be used in thedesign of sector roads.

Left Turn Lanes - Left turn lanes shall not beused in the design of sector roads.

Parking Loading/Unloading Lanes - Generally,no loading or unloading lanes shall be provided onSector Roads. It is up to the designer and DesignProject Manager to determine the need and typeof on-street sector road parking. If required, seeSection 211, Parking.

Median - Sector roads shall not have medians.

Curbs - Curbs shall be provided along the outsideedge of sector roads. Types and uses are shown inthe current Standard Drawings.

Sidewalks - Sidewalk widths and locations willvary but minimum width shall be 2.0 m.Whenever possible a 2.0 m wide sidewalkdividing the pavement and green areas should beprovided. The sidewalk surface will slope towardthe roadway at a uniform cross slope of 1.0percent.

Pedestrian crosswalk ramps shall be used at allintersections and all other locations where mainpedestrian traffic crosses curb lines.

Cross Slope - All pavement will have a 1.5percent uniform cross slope either at a straightcross slope from one edge of pavement to theother or by utilizing a crowned roadway design.Sector roads shall not have superelevation.

Profile Grade Line - The profile grade line forsector roads shall be the centerline or asdetermined by the Consultant.

305.05 FRONTAGE ROAD CROSSSECTION

Pavement and Lane Widths - The minimumpaved cross section for urban frontage roads shallbe two 3.65 m lanes with curbing. The minimumpaved cross section for rural frontage roads shallbe 3.65 m lanes with 1.2 m paved shoulders.

Cross Slope - All pavement will have a 1.5percent uniform cross slope either at a straightcross slope from one edge of pavement to theother or by utilizing a crowned roadway design.

Outer Separation - Outer separation is thedistance from the main road travelled way to thefrontage road travelled way. In urban andmountainous areas, the outer separation should be8.0 m minimum. In rural areas, other thanmountainous terrain, the outer separation should12.0 m minimum.

Headlight Glare - Frontage road design shallaccount for potential headlight glare interferingwith the vision of oncoming motorists. Thepreferred measures to prevent headlight glareinterference on new construction are wider outerseparations, revised alignment and raised orlowered profiles.

306 HORIZONTAL AND VERTICALCLEARANCES

306.01 HORIZONTAL CLEARANCES

Unshielded Horizontal Clearance - Theminimum desired horizontal clearance between thetravelled way edge and fixed objects shall be theclear zone width. Fixed objects within the clearzone shall be eliminated, moved, redesigned(breakaway design), or shielded (see barrierdesign below ) where practical.

Shielded Horizontal Clearance - If fixed objectscannot be eliminated, moved or redesigned thenlesser clearance is allowable if barriers orguardrail is used to shield the object.

The clearance to fixed objects such as bridgerails, concrete barriers, abutments, retainingwalls or noise barriers on all roadway facilities,shall be equal to the standard roadway shoulder


Part 2 300-6

width stated in Table 300.01, except that aminimum clearance of 1.2 m shall be providedwhere the standard shoulder width is less than1.2 m. Approach rail connections to bridge railmay require special treatment to maintainstandard shoulder width. Safety shaped barrierface shall be constructed integrally at the base ofany retaining wall, pier, or abutment which facestraffic and is less than 4.6 m from the edge oftravelled way.

Curbed Roadway Sections - A minimumhorizontal clearance of 1.0 m should be providedalong intersection curb returns and near drivewayedges to allow for design vehicle off tracking.Where sidewalks are located immediatelyadjacent to curbs, fixed objects should be locatedbehind the sidewalk, providing an unobstructedpedestrian area.

306.02 VERTICAL CLEARANCES

General - Efforts should be made to avoiddecreasing the existing vertical clearancewhenever possible and consideration should begiven to increasing vertical clearance on projectsinvolving structural section removal andreplacement.

Structure Type Vertical Clearance(m)

Pavement Surface to nearestunderside of superstructure. 6.0

Sign Structures 5.5

Overhead Communication Lines 7.0

Power Lines (Volts)0 - 750 7.0

750 - 15,000 9.015,000 and greater 10.0

Pedestrian Overpass 6.0

Pedestrian Overpass withOverhead Guide Sign 6.0

306.03 TUNNEL CLEARANCES

Horizontal Clearances - The minimumexpressway tunnel width should equal the fullapproach travelled way width plus pavedshoulders.

In one-way tunnels on conventional roadways theminimum side clearance from the edge of thetravelled way (unless sight distance dicatatesotherwise) shall be 1.5 m on the left and 2.0 m onthe right. For two-way tunnels, this clearanceshall be 2.0 m on each side.

Vertical Clearances - The desirable verticalclearance shall be 6.0 m measured at any pointover the travelled way. Lesser clearance may beapproved by the Municipality Road Section.

307 CLEAR ZONE CONCEPT

Clear Zone - A clear zone is an unobstructed, flator gently sloping area beyond the travelled wayedge. It gives drivers the opportunity to regaincontrol of errant vehicles. The clear zone ismeasured horizontally from the travelled wayedge to the nearest point on an obstruction. Wherefeasible, fixed objects should not be locatedwithin the clear zone.

In an area where the roadside is relatively clear,flat and straight, application of the clear zoneconcept is straightforward. However, factorssuch as roadside embankments, space restrictionsand roadway curvature and superelevationcomplicate the application of the clear zone.

Clear Zone Standard - The clear zone widthrequired is based on geometry, traffic volumes,and operating speeds as shown on Figure 300.02.

Curvature Correction Factors - Figure 300.03shows correction factors used to adjust the clearzone distances, taking into account roadwaycurvatures. These modifications should be usedonly in locations with high accident rates andwhere increasing the clear zone distance is costeffective.


Part 2 300-7

Figure 300.02Clear Zone Distance Curves


Part 2 300-8

Figure 300.03Horizontal Curve Adjustments Factors

307.01 APPLICATION OF CLEARZONE

307.01.01 Roadside Terrain: Foreslope

When a roadway is on an embankment, the sideslope is called a foreslope (negative slope) whichcan be recoverable, non-recoverable, or critical:

Recoverable - A recoverable slope is one that anerrant vehicle can drive across, slow down, stop,and return to the roadway. Recoverable slopesare 1:4 or flatter, relatively smooth, and clear ofall fixed object hazards. The top of the slope shallbe rounded so a vehicle’s wheels remain incontact with the roadway when encountering theembankment. The toe of slope shall also berounded so the driver is able to negotiate anddrive across if the vehicle reaches the base of theembankment.

Non-recoverable - A non-recoverable slope isone which an errant vehicle can be driven acrossbut may not be able to slow down or stop before

reaching the base. Embankments with slopesbetween 1:3 and 1:4 generally fall under thiscategory. A smooth clear run-out area with aslope of 1:6 or flatter, in addition to therecommended clear zone distance is recommendedat the base of the slope. The width of the runoutarea is determined according to the availablewidth between the edge of traveled way and thebreakpoint between the flatter (1:4 and flatter)and steeper (1:4 and 1:3) slope of theembankment. This available width is thensubtracted from the clear zone distance obtainedfrom Figure 300.02, based on the steeper slope ofthe embankment. The difference is the width ofthe clear runout area. See Figure 300.04 forexample.

Critical - A critical slope is one where a vehiclehas a high probability of overturning, slopessteeper than 1:3 fall in this category. If theavailable clear zone is narrower than therecommended width or it is not practical to adjustthe roadside geometry, installing a barrier systemmay be necessary.


Part 2 300-9

307.01.02 Roadside Terrain: Backslope

When a roadway is located in a cut section, thecut slope is called a backslope. A traversablebackslope is 1:3 or flatter, relatively smooth,clear of fixed object hazards, and where a vehiclecan be driven across without becoming stranded.This type of backslope can be included as part ofthe clear zone. However if the backslope issteeper than 1:3, rock cut or rough sided, the baseof the backslope shall be outside the clear zone.If the recommended clear zone can not bepractically accommodated, a barrier system maybe required to protect motorists.

307.01.03 Roadside Terrain: Cross-slope

Cross-slopes can be located along medians,intersecting driveways and roadways. Crossslopes can be more hazardous to motorists thanforeslopes or backslopes because of thepossibility of colliding with opposing traffic.Cross-slopes of 1:10 or flatter, traversable,relatively smooth, and clear of fixed objecthazards are recommended particularly in mediansimmediately adjacent to opposing traffic. Inroadside sections where 1:10 can not beaccommodated, such as urban areas, a maximumslope of 1:6 should be used.

307.01.04 Roadside Terrain: Ditch

The primary function of ditches is to preventroadways from flooding by directing and carryingwater away from the roadway. They areespecially hazardous because of fixed hazardssuch as, exposed pipes, headwalls and culverts.The ditch cross section itself can also represent aserious hazard. Preferred ditch cross sections aretraversable and free of hazards. See Figures300.05 and 300.06. Cross sections that fallwithin the shaded area are considered traversable.Cross sections that fall outside the shaded regionsare considered less desirable and should be usedonly under conditions of:• restricted ROW• rugged terrain• resurfacing, restoration or rehabilitation• low volume or low speed roadsConditions where a ditch has a cross section thatfalls outside the shaded region, and is located in avulnerable location shall consider closed drainagesystems or shielding with barrier systems.

Figure 300.04Clear Runout Area


Part 2 300-10

Figure 300.05Preferred Vee-Ditch Cross Sections

Figure 300.06Preferred Trapezoidal ditch Cross Sections


Part 2 300-11

308 BARRIERS

308.01 BARRIER NEED

The roadside barrier’s primary function is toprevent errant vehicles from leaving the roadway.Barrier need is based on the premise thatinstalling a barrier will reduce the number ofaccidents and/or reduce the magnitude of anaccident at that location. The engineer must alsoevaluate the barrier installation itself to be lesshazardous than the hazard. Efforts shall be madeto eliminate hazards within the clear zone prior toconsidering any barrier installations.

When determining barrier requirements, thefollowing factors must be considered:• Risks involved with encroaching on a hazard

versus colliding with a barrier.• Evaluating roadway design speed and traffic

volumes to barrier need.• Evaluating costs of installing and maintaining

a barrier system versus not installing a barriersystem.

• Costs of accidents involving barriers versusnot involving a barriers.

Figure 300.07 for example, compares the risksinvolved with encroaching on an embankmentversus colliding with a barrier. Embankmentsthat fall outside the shaded region do not warrantshielding. Figure 300.07 however does not nottake into account other factors such as, objecthazards on the embankments within the clearzone, installation and maintenance costs of abarrier system, and accident costs involving abarrier system. All these factors must beconsidered together when evaluating barrierneeds.

As previously stated, if hazards exist within theborders of the clear zone, efforts shall be made toeliminate the hazard first, prior to consideringbarrier installation. These considerations caninclude any of the following:• Regrading of roadside topography in the clear

zone to a smooth and safe cross section.• Extend exposed pipes, culverts and install

headwalls outside the clear zone.

• Install drop inlets for roadside drainagesystems rather than exposed pipes andculverts.

• Remove or relocate all manmade or naturalfixed obstacles such as utility poles, signs,luminare supports, trees, and boulders.

• Install breakaway bases for signs andluminare supports if removal or relocation isnot practical.

308.02 ROADSIDE BARRIER TYPESAND FEATURES

There are two types of roadside barrierscommonly used. See Figure 300.08.

• Blocked-Out W-Beam Barrier• Roadside Concrete Barriers

Block-Out W-Beam Barrier - This barriersystem is the mainly used as a guardrail system.It shall be installed in most locations thatwarrants a guardrail system, except for urbanareas and locations that require a concrete barrier.This system has been tested to successfullyredirect 800-2000 kg vehicles. It has alsosuccessfully redirected a 2100 kg van at impactconditions of 21° at 95 kph.

Concrete Safety Shape Barrier - The concretesafety shape roadside barrier is a rigid systemdesigned to redirect vehicles without anydeflection. Because of its rigidity, vehicles wouldhave a higher probability of overturning orvaulting over the barrier. Therefore, shape of thefront face of the barrier is critical to itsperformance. The distance from the top of theroadway surface to the break between the upperand lower slopes shall not exceed 330 mm.

Roadside barriers are also designed with varyingheights to counteract overturning moments oftrucks with high centers of gravity. The basicroadside barrier is designed at 810 mm high. Atthis height, the roadside barrier can successfullyredirect 820-2000 kg vehicles, and occasionallyredirect 18,000 kg buses at moderate impact. Aroadside barrier designed at 1070 mm high, havesuccessfully redirected a 36,300 kg tractor-trailerwith impact conditions of 15° at 84 kph.


Part 2 300-12

Figure 300.07Risk Warrants for Embankments

308.03 ROADSIDE BARRIERPLACEMENT

308.03.01 Lateral Placement

Placement of a barrier system shall be determinedin a manner that increases motorist safety,decreases accidents and minimizes injuries. Abarrier system shall shield the motorist fromroadway hazards and not contribute to the hazard.It is therefore a standard rule that the barriersystem shall be placed as far from the edge oftravelled way as possible. This allows driversroom to regain control of their vehicle andpossibly avoid an accident. It is important to notehowever; as the distance between the edge oftravelled way and the barrier increases, thepotential angle of impact of the vehicle alsoincreases. Barriers at high angle of impacts aresignificant hazards themselves.

308.03.02 Barrier to Hazard Clearances

In cases when a roadside barrier is required toshield an isolated hazard, clearance must beprovided between the barrier and the hazard.Upon impact, some barriers will deflect, makingthe clearance between the barrier and the hazardimportant. Furthermore, if a barrier is struck bya vehicle with a high center of gravity, the vehiclemay roll or vault over the barrier. If sufficientdistance is not provided, the vehicle may collidewith the hazard. Sufficient distance must beprovided between the barrier and the hazard beingshielded.


Part 2 300-13

308.03.03 Effects of Roadside Terrain

The profile between the edge of traveled way andthe barrier can have significant effects on the finalplacement of the barrier. The vehicle’s wheelsshould remain in contact with the ground and itssuspension system neither compressed orsuspended at the moment of impact with thebarrier. This holds true for all barrier systems.Locations of roadside curbs and slopes requireparticular attention when determining barrierdesign and placement.

Curbs - Guardrail/Curb combinations are highlydiscouraged in locations where high-speed andhigh angle impacts are likely to occur. Areaswith no alternative but to use this combinationshall use a curb less than 100 mm or, stiffen theguardrail to reduce deflection by bolting a w-beam to the back of the posts or by adding a rubrail.

Slopes - As previously mentioned, guardrailperformance is affected by the vehicle’s positionat moment of impact. Crash tests show, roadsidebarriers perform most effectively when installedon slopes 1:10 or flatter.

308.03.04 Barrier Length Design

Runout Lengths (LR) and Hazard LateralDistance (LH) - When designing the length of abarrier, the two primary factors that must beconsidered are:

• LR - Runout Length• LH - Hazard Lateral Distance

The runout length (LR) is the distance a vehicleneeds to stop prior to colliding with a hazard onceit has left the roadway. Its distance is measuredfrom the point the vehicle is assumed to leave theroadway to the hazard ahead. Runout lengthrequirements vary according to the roadwaydesign speed. See Figure 300.04.

The lateral distance (LH) is the distance betweenthe edge of the travelled way to the far side of thehazard, if the hazard is a fixed object. If thehazard is an embankment, the lateral distancewould be extended to the edge of the clear zone.If the hazard extends beyond the clear zone, theminimum lateral distance would be only to theedge of the clear zone.

After determining the runout length and lateraldistance, the length of the barrier depends on thebarrier tangent length, barrier lateral offset, andflare rate.

Figure 300.08Roadside Barrier Types and Features


Part 2 300-14

Figure 300.09Barrier Layout Diagram


Part 2 300-15

Barrier Tangent Length (L T) and BarrierLateral Offset (L 1) - The barrier tangent length(LT) is the portion immediately ahead from thehazard and parallel to the roadway. It is ofvariable length, selected by the designer, andshall be at least as long as the flared section of thebarrier.

The barrier’s lateral offset (L1) is the distancebetween the edge of travelled way to the barrier.This offset is also selected by the designer andshall be as far away from the edge of travelledway as possible. This provides an unobstructedrecovery area to allow an out of control vehicle togain control without colliding with the barrier.

Flare Rate (b:a) - The flared portion of thebarrier is not parallel to the roadway. Flaredsections are used mainly to introduce the barriertoward the barrier line or a narrower segment ofthe roadway. The flared transition decreases thelikelihood that the barrier is perceived as a hazardby motorists.

Flared barrier sections have their disadvantages.The greater the flare rate, the greater the angle ofimpact from an approaching vehicle. This mayincrease the magnitude of injuries particularlywith rigid barriers. Barrier flares can alsoincrease the probability that an impacting vehiclewill be redirected across the roadway and intoincoming traffic. This is particularly dangerous ifthe roadway has two-way traffic not separated bya median or a median barrier. Therefore, flatterflare rates shall be used particularly in locationswith two-way traffic or steep embankments.

See Figure 300.09 for barrier layout diagram.

308.04 MEDIAN BARRIERS

308.04.01 Median Barrier Warrants

A Median barrier’s primary function is toseparate opposing traffic on a divided roadwayand/or shield fixed object hazards within themedian. Like all types of barriers, medianbarriers shall only be installed if it is lesshazardous colliding with the barrier than nothaving a barrier installed at all. Barrierinstallation shall be considered only if the fixedobject hazards can not be removed.

Median barriers are warranted in locations thathave a history of cross-median accidents. Onroadways that have wide medians, (greater thannine meters) median barriers generally are notwarranted unless there is a history of cross-median accidents or there are fixed object hazardswithin the median.

308.04.02 Median Barrier Types andFeatures

There are three types of commonly used medianbarriers. See Figure 300.10.

• Concrete Safety Shape Median Barrier• Single Face Concrete Barrier• Metal-Beam Guardrail

The concrete safety shape barrier is the mostcommonly used median barrier, and shall beinstalled in most locations requiring a barrier. Inareas where the adjoining sections of roadwayhave previously installed a Metal Beam Guardrailconsideration may be given to continue using itfor that segment. Single face Concrete Barriersare used mainly to shield hazards or for earthberm support.

308.05 MEDIAN BARRIERPLACEMENT

The two primary factors to consider when placingmedian barriers are:

• Median Geometry• Treatment of Fixed Object Hazards in the

Median

308.05.01 Median Geometry

As previously mentioned, a median that is flat(1:10 or flatter), relatively smooth and clear offixed obstacles is desirable. If a median barrier iswarranted under these conditions, it shall beinstalled at the center of the median.

If the median is a v-shaped foreslope embankmentor a ditch and warrants a barrier, it shall beinstalled near the shoulder on both sides of themedian.


Part 2 300-16

If the full width of the median is a foreslopeembankment steeper than 1:10, and warrants abarrier, the barrier shall be installed on the higheredge of the median. If the slope is 1:10 or flatterand requires a barrier, the barrier shall beinstalled at the center of the median. However, ifthe median is rough cut, obstructed with hazards,and non-traversable, barriers shall be installed, atthe edge of both shoulders.

If the median is a backslope that is rough cut,non-traversable or is inside the clear zone area,barriers shall be installed on both sides of themedian to avoid vehicle snagging. If thebackslope is traversable but sufficiently steep toredirect vehicles, a semi rigid barrier can beinstalled on the high point of the slope.

308.05.02 Treatment of Fixed ObjectHazards

In some situations, the entire median does notrequire a barrier system. However, there may behazards in the median that require shielding.Treatment of hazards can include but not limitedto those illustrated in Figure 300.11.

308.06 END TREATMENTS ANDCRASH CUSHIONS

308.06.01 End Treatments

All roadside and median barriers terminatingwithin the clear zone and/or are located wherethey have a high probability of being hit head-on,shall terminate with a crashworthy terminal on theapproach end of the barrier. Refer to the mostrecent edition of the AASHTO Roadside DesignGuide.

Figure 300.10Median Barrier Types and Features


Part 2 300-17

Figure 300.11Treatment of Fixed Hazards


Part 2 300-18

308.06.02 Crash Cushion

A Crash Cushion’s main function is to decreasethe magnitude of an accident by absorbing someof the force from an impact. They are effective ingradually slowing down and stopping or safelyredirecting errant vehicles in head-on and sideimpact collisions.

Crash Cushions shall be used to shield hazardousconditions and fixed object hazards that can notbe removed, relocated or designed to breakaway.These include ends of bridge barriers, rails andbridge piers in gore areas. Crash Cushions arealso commonly used at ends of roadside andmedian barriers .

Selection Guidelines

The selection criteria for crash cushions differ ineach individual case. Engineers must evaluateeach hazard and select the most effective andappropriate crash cushion system for that case.Refer to the most recent edition of the AASHTORoadside Design Guide.

The minimum requirement for a crash cushionsystem shall have the following characteristics:

• The system shall be able to stop or redirect acolliding vehicle without any debrispenetrating the passenger compartment of thevehicle.

• The colliding vehicle shall remain in theupright position and not violently redirectedto other traffic.

308.06.03 Placement Recommendations

Crash Cushion systems perform best on relativelyflat surfaces. Therefore they shall be installed onhard level surfaces such as portland cementconcrete or hot bituminous concrete pads. Thisallows the crash cushion system to compressuniformly throughout the impact. The pathbetween the roadway and the crash cushions shallbe relatively smooth and clear of obstructions.Ideally the vehicle’s suspension systems shouldnot be collapsed or extended when it collides withthe crash cushions.


Part 2 400-1

SECTION 400AT-GRADE INTERSECTIONS

401 GENERAL

An intersection is the area where two or moreroadways connect. It includes the roadway androadside facilities available for traffic movement.Each roadway radiating from an intersection iscalled an intersection leg.

Intersection design is very important to the overallroadway safety and level of service. Manyaccidents and safety problems occur atintersections. Intersection type and spacingcontrol roadway capacity and travel time.Intersections handle a variety of conflicts amongvehicles and pedestrians. Vehicles arriving,departing, merging, turning, and crossing traffichave to be accommodated within a relativelysmall area. These movements may be handled byvarious means, depending on the intersection type.

There are three categories of roadwayintersections. This section deals with at-gradeintersections. Grade separations (i.e., withoutramps), and interchanges are discussed in Section500.

402 DESIGN CONSIDERATIONS

Intersection design affects roadway efficiency,safety, capacity, operating cost and operatingspeed. Well designed intersections reduce theseverity of user conflicts while accommodatingtheir varied interests. Intersection design is acooperative effort between roadway and trafficengineers, based on human factors, trafficconsiderations, physical elements and economicfactors.

403 AT GRADE INTERSECTIONTYPES

There are three basic types of at-gradeintersections, the three-leg intersection, the four-leg intersection, and the multileg intersection. SeeFigure 400.01. Factors in determining the type ofintersection include, the number of

Figure 400.01Basic Intersection Types


Part 2 400-2

intersecting legs, topography, traffic patterns, anddesired operation. Intersections within a basictype vary greatly however, the general applicationof at-grade intersection design is common to all.Traffic volume, design speed, and the roadwayclassification are the principal factors used todetermine intersection type.

Three-Leg Intersection - The three-legintersection has three intersecting legs which forma “T” or a “Y”. Operationally three-leg and four-leg intersections are preferred and multidirectional"Y" intersections and intersections with more thanfour legs should be avoided.

Four Leg Intersections - Four-leg intersectionsmay be right angled, oblique, or offset. The right-angled crossing is easily signed and signalized,provides good visibility, and is the safest tonegotiate. The oblique crossing creates problemswith visibility, pedestrian safety, and vehicle-turning angles. The offset intersection has lowcapacity, is difficult to comprehend and negotiate,and is difficult to sign and signalize.

Multileg Intersections - These intersections havemore than four legs and can have severalconfigurations. Multileg intersections areconfusing, have poor visibility, poor turningangles, and are difficult to sign, mark, andsignalize. This type of intersection should beavoided if possible.

Roundabout Intersections - Roundabout designsgenerally have three or four legs joining a circularroadway. All traffic turns right to merge withtraffic in the roundabout. Traffic continues toturn right through the circle to eliminate throughand left turn movements. Roundabout designs arecharacterized by light traffic volumes and slowspeeds through the intersection. The roundaboutintersection is a design that can be used in lieu ofthe traditional three or four leg intersections. Forfurther descriptions and types see Part 2, Section407, Roundabout Design.

404 CHANNELIZATION

Channelization is the separation of traffic intodefinite travel paths using pavement markings orraised islands. Channelization should be used to:

• Give preference to major traffic movements.• Reduce areas of conflict.• Cross traffic at right angles (75-90o desirable

- skew no more than 60o.)• Separate points of conflict.• Provide speed-change lanes and separate

turning lanes where appropriate.• Restrict undesirable movements.• Provide adequate width to shadow turning

traffic.• Enhance signal control.

404.01 PREFERENCE TO MAJORMOVEMENTS

Whenever possible, preference should be given tothe major traffic movements. This usually requiresstopping, funneling, or eliminating minormovements. Controlling measures should conformto natural movement paths and be introducedgradually to promote smooth and efficientoperation.

404.02 AREAS OF CONFLICT

Large multilane undivided intersection areas areundesirable because drivers cannot predict theother vehicles movements. By separating trafficmovements into definite travel pathschannelization reduces these conflicts.Channelization also separates points of conflictwithin the intersection and clearly defines vehiclepathways.

404.03 INTERSECTION ANGLES

A 90o intersection provides the shortest crossingfor intersecting traffic and provides the mostfavorable condition for drivers to judge therelative position and speed of approachingvehicles. The minimum desirable intersectionangle is 75 degrees. Intersection angles less than60 degrees should be realigned.

404.04 POINTS OF CONFLICT

Points of conflict occur when drivers paths cross.The highest number of conflicts occur atintersections. For example, a driver making aleft turn on to a roadway must cross right-boundtraffic and merge into the left-bound traffic


Part 2 400-3

stream. That single maneuver causes conflictwith both directions of travel. Where everpossible, points of conflict should be reduced sodrivers are only exposed to one conflict ordecision at a time. This can be done by usingstop signs, traffic signals, grade separations, andchannelization. Channelization separates andclearly defines points of conflict within theintersection.

Channelization separates and clearly definespoints of conflict within the intersection. Driversshould be exposed to only one conflict orconfronted with one decision at a time.

404.05 SPEED-CHANGE LANES

Speed-change lanes improve intersection safetyand efficiency. Entering traffic merges mostefficiently with through traffic when the mergingangle is less than 15o and speed differentials areat a minimum.

Speed change lanes for diverging traffic shouldpermit vehicles to decelerate after leaving thethrough lanes.

404.06 TURNING MOVEMENTS

A separate right turning lane removes turningmovements from the intersection area, increasingsafety and capacity. Also adding dedicated leftturn lanes removes left turn traffic from the thrulanes which also increases safety and capacity.Abrupt changes in alignment or sight distanceshould be avoided.

404.07 REFUGE AREAS

Properly sized traffic islands can provide refugefor vehicles and pedestrians. The shadowingeffect of islands provides refuge for vehicleswaiting to cross or enter an uncontrolled trafficstream.

Channelization can also provide a safer crossingof two or more traffic streams by permittingdrivers to select adequate gaps in one trafficstream at a time. Channelization should alsoprovide ample storage for vehicles to make theturning or crossing movements.

404.08 PROHIBITED TURNS

Traffic islands may be used to divert trafficstreams in desired directions and prevent specificundesirable movements.

404.09 EFFECTIVE SIGNAL CONTROL

At intersections with complex turningmovements, channelization is required foreffective signal control. Channelization enablessorting and storing of approach traffic for orderlymovement through the intersection duringseparate signal phases. Channelization isparticularly effective when used with traffic-actuated signal controls.

404.10 INSTALLATION OF TRAFFICCONTROL DEVICES

Traffic islands enhance the effectiveness of, andprovide space for, traffic control devices such assignals and signs. Dimensions and clearances fortraffic control devices should be considered whensizing traffic islands.

404.11 GUIDELINES

• Striping is preferable to curbed islands,especially adjacent to high-speed trafficwhere curbing can be an obstruction to out-of-control vehicles.

• Where curbing must be used, first

consideration should be given to mountablecurbs. Barrier curbs should only be usedwhere pedestrian protection is a primaryconcern.

• Avoid complex intersections that present

multiple movement options or decisions. • Accident records provide a valuable guide to

the type of channelization needed.

• The Standard Drawings include details for achannelized free right turn and typicalpavement markings at intersections.


Part 2 400-4

405 DESIGN VEHICLES

405.01 OFF TRACKING

A vehicle traveling around a circular curvesweeps a wider path than the width of thevehicle. The difference between the swept widthand the vehicle width is called off tracking. Onlarge trucks and buses offtracking can besignificant and must be considered in design.

405.02 DESIGN VEHICLES

Intersection geometric design depends on thedimensional and operational characteristics of thevehicles involved. The American Association ofState Highway and Transportation Officials haveadopted "design vehicles" representing the variousclasses of commonly used vehicles.

For freeways and expressways, the design vehicleshall be a WB-12 medium tractor semi-trailercombination. For arterials, collectors and sectorroads, the design vehicle will be a single unit bus.Design vehicles are as defined in “A Policy onGeometric Design of Highways and Streets”,AASHTO, 1994. Dimensions for various designvehicles are shown in Figure 400.02.

405.03 TURNING TEMPLATES

Turning templates are used to locate the turningpaths of large vehicles. The template is used todetermine corner radii, position island noses,establish clearances and the width of channeledseparate turning lanes. Turning templates for thevarious design vehicles are shown in Figure400.03. It should be noted that state-of-the-artturning template computer software exists whichcan be used in-lieu of Figure 400.03.

406 INTERSECTION DESIGNSTANDARDS

406.01 SIGHT DISTANCE

General - The Driver of a vehicle should have anunobstructed view of the entire intersection.Stopping sight distance shall be the minimumprovided throughout all parts of intersections.

Approach Sight Triangle - The area boundedby the required sight distances along theintersection legs and the sight line connectingtheir ends is known as the "sight triangle". SeeFigure 400.04.

Unobstructed sight distance along all intersectionapproaches and across the included corners mustbe sufficient to permit operators of approachingvehicles to perceive each other, react andcomplete an appropriate accelerating, slowing orstopping maneuver. If all corners of theintersection cannot be cleared and maintained toprovide unobstructed views in the approach sighttriangle, the intersection shall have stop controlimposed.

Departure Sight Triangle - The departure sighttriangle is bounded by the location of the stoppeddriver, the appropriate sight distance along theintersecting road, and the connecting sight line.See Figure 400.04. The driver must havesufficient sight distance along the intersectinglegs to make a safe departure movement. Allcorners of the intersection shall be constructed toprovide a clear line of sight throughout thedeparting sight triangle.

Intersection Controls - The following controlsapply to at-grade intersections.

• No Control - vehicles need sufficient sightdistance to adjust their speed.

• Yield Control - Vehicles on minor roadwayyield to vehicles on major roadway.

• Stop Control - Vehicles on minor roadwaystop at major roadway.

• Signal Control - All legs are controlled byeither stop signs or traffic signals.

• Left-turn Control - Stopped left-turningvehicles on minor roadway must yield toopposing vehicles on major roadway.

No Control - For a given speed, the approachsight triangle is determined from Figure 400.04and Table 400.01. Departure sight trianglesshould be commensurate with those provided atstop controlled intersections.


Part 2 400-5

Table 400.01Sight Triangle DistancesNo Intersection Control

Vehicle Speed (kph) Distance (m)20 2030 2540 3550 4060 5070 6080 6590 75100 85110 90120 100

The sight triangle dimensions are determined usingthese distances per Figure 400.04 for No Control.These distances are based on level roadways.

Yield Control - Approach sight triangles shouldbe provided at all intersection corners. Minimumsight distances provided along the legs should beat least stopping sight distance. For departuresight triangles see “Stop Control”.

Stop Control - Adequate sight distance must beprovided so a driver traveling at the design speedcan perceive and safely stop at the stop sign.Once stopped, the driver must have adequate sightdistance on the major road to permit safedeparture movements.

The three basic departure movements are:

• To travel across the intersecting roadway,clearing oncoming traffic in both directions;

• To turn left onto the intersecting roadway,clearing oncoming traffic from the left andentering the traffic stream coming from theright;

• To turn right onto the intersecting roadwayby entering the traffic stream coming from theleft.


Part 2 400-6

Figure 400.02Design Vehicle Dimensions


Part 2 400-7

This turning template shows the turning paths of the specified AASHTO design vehicle. The paths shownare for the left front overhang and the outside rear wheel. The left front wheel follows the circular curve,however, its path is not shown.

Figure 400.03Minimum Turning Path for P Design Vehicles

From AASHTO, 1994, “A Policy on Geometric Design of Highways and Streets


Part 2 400-8

FOR APPROACHING VEHICLE

FOR DEPARTING VEHICLE

Figure 400.04Intersection Sight Triangles


Part 2 400-9

Stop Control with Crossing Maneuver -Crossing maneuver sight distance is based on thetime it takes for the stopped vehicle to clear theintersection and the distance travelled in that timeby an oncoming vehicle on the cross road. Thedistance may be calculated from

d = 0.28V(2.0+ta)

where: d = sight distance required alongthe major roadway from theintersection (m).

V = design speed on the majorroadway (kph)

ta = time required to accelerate andtraverse the distance to clearthe major roadway travelledway (s)

The solid line curves in Figure 400.05 labeled“P”, “SU” and “WB-15” are the recommendedvehicle time-distance relationships to compute ta.

If significant grades are present, ta should beadjusted per Table 400.02.

The distance that a crossing vehicle travels toclear a major roadway is:

S = D+W+L

where: D = distance from near edge-of-travelled way to the front of astopped vehicle (typically 3.0m).

W = travelled way width along pathof crossing vehicle (m)

L = overall length of vehicle (m)

Calculated sight distance shall be checked againststopping sight distance. The larger of thedistances shall be used.

Figure 400.05Sight Distance at Intersections Acceleration

from Stop.From AASHTO, 1004, “A Policy on Geometric

Design of Highways and Streets”


Part 2 400-10

Turning Left Onto a Major Roadway -Because it takes longer to turn and accelerate tooperating speed than to go straight across anintersecting roadway, the critical sight distancesare those required for turning movements. Thedriver must have sufficient sight distance to theleft to cross the near lanes(s) without interferingwith oncoming traffic. The driver must also havesufficient sight distance to the right to turn leftand accelerate to a speed where oncoming trafficis not significantly impaired.

The sight distance required to the left arecalculated from:

dL = 0.28V(2.0+ta)

where: dL = sight distance required to theleft along the major roadwayfrom the intersection (m).


ta = time required to accelerate andtraverse the distance to clearthe traffic in the laneapproaching from the left.

The required sight distance to the right is basedon the assumption that the mainline vehicle willslow to 85 percent of the design speed andmaintain a 2.0 second gap from the turningvehicle. To calculate the necessary sight distancefirst determine from Figure 400.06 the distance Prequired for the turning vehicle to reach a speedof 85 percent of the mainline design speed. Thesight distance required to the right is calculatedfrom:

dR = (t+2)(.28)(.95V) - (P-5-(.56)(.85V) - Lv)

where: dR = Sight distance required tothe right along the majorroadway from theintersection (m).

T = time required to traveldistance P (Table 400.01).

V = mainline design speed(kph)

Lv = Vehicle Length (m)

Turning Right Onto a Major Roadway - Theright-turning-vehicle must have sufficient sightdistance to the left to complete its turn andaccelerate to a predetermined speed before beingovertaken by approaching traffic travelling at thesame predetermined speed. The sight distance

requirement for the right-turn maneuver isapproximately one meter less than that requiredfor the left-turn maneuver in “Turning Left Ontoa Major Roadway”. See Figure 400.07 curve Cbfor the required sight distance for a vehicleturning right and accelerating to 85 percent of thedesign speed before being overtaken by vehiclesslowing to 85 percent of design speed. Truckswill take considerably longer than passengervehicles.

Signal Control - Because of unanticipatedvehicle conflicts at signalized intersections, (suchas, signal violations, right-turns on red, signalmalfunction, or use of flashing red/yellow mode)the requirements for Stop Controlledintersections should be met. At intersectionswhere right-turns on red are permitted, thedeparture sight line for right-turning vehiclesshould be determined by the methods for“Turning Right into a Major Roadway."

Stopped Vehicle Turning Left from a MajorRoadway - The driver will need sufficient sightdistance ahead to turn left and clear the opposingtravel lane(s) before an approaching vehiclereaches the intersection. The sight distancerequired is calculated from:

d = 0.28V(2.0+ta)

where: d = sight distance required alongthe major roadway from theintersection (m).


ta = time required to accelerate andtraverse the distance to clearthe traffic in the approachinglane.

406.02 EFFECT OF SKEW

Intersection skew has no effect on sight distancerequirements since they are measured along theintersecting legs. However, the sight triangleconfiguration is affected by skew. Care should betaken to verify that the area within the sighttriangles can be constructed and maintained toprovide a unobstructed view throughout the sighttriangle with a 1070 mm eye height on the minorroad to a 1300 mm object height on the majorroad.

Skew also affects the distance a vehicle travels tocross the intersection. Heavily skewedintersections should be controlled.


Part 2 400-11

Figure 400.06Acceleration Curves



Part 2 400-12

Figure 400.07Intersection Sight Distances

For turning onto a major roadway AASHTO, 1994,“A Policy on Geometric Design of Highways and Streets”


Part 2 400-13

406.03 EFFECT OF VERTICALPROFILES

A vehicle descending a grade requires greaterstopping distance than one on level ground.Conversely, a vehicle ascending a grade requiresless distance to stop. Grades up to 3 percent havelittle effect on stopping sight distances. In no caseshould the grades exceed 6 percent.

For Stop Controlled intersections, the timerequired to cross a roadway is affected by thecrossing grade. If the grade is significant, thesight distance should be increased.

Where the intersection leg grades are other thanflat, corrections should be made to the sightdistances using the approximate ratios given inTable 400.02.

Table 400.02ta Adjustment For GradeSight Triangle Distances

Ratio, ta on grade / ta level (Figure 400.05)

Crossroad Grade %

Design Vehicle -4 -2 0 2 4P 0.7 0.9 1.0 1.1 1.3SU 0.8 0.9 1.0 1.1 1.3WB-15 0.8 0.9 1.0 1.2 1.7

Use this table to adjust ta values for effect ofgrade. Based on the likely range of crossingdistances.

406.04 LEFT-TURNCHANNELIZATION

General - A left-turn lane expedites throughtraffic flow, controls turning traffic movement,and improves the intersection safety and capacity.

The left-turn lane should be laid out such that theturning vehicle must make a definite move toenter the lane. The desirable length of the left-turnlane is the sum of the required storage length anddeceleration length, including the bay taperlength.

Width - The desirable left-turn lane width should

be 3.65 m. Three meter wide left-turn lanes maybe used on low speed urban roadways. The widthis measured from the adjacent edge of travelledway, excluding shy distance.

Medians - To improve left-turn visibility, the left-turn-lane should be placed as far to the left aspossible in the median leaving only the painted orcurbed nose. Excess width between the left-turnlane and the adjacent same-direction through laneshould be treated as painted island. When left-turn lanes are placed in raised (curbed) medians,a minimum nose width of 1.0 m should remain forpedestrian refuge and traffic control devices.

Approach Tapers - On roadways with narrow orno medians, room for the left-turn lane is made byshifting traffic laterally to the right. The taperlength used to effect this shift should be 0.6WV,where W = lateral shift (m) and V = design speed(kph).

Bay Tapers - The bay taper length should beshort to clearly identify the additional lane.Generally the taper length should be 15:1.

Deceleration Length - Whenever feasible, theleft-turn lane should provide deceleration clear ofthe through lanes. The minimum decelerationlengths, exclusive of bay taper and vehiclestorage, for 50, 60 and 80 kph are 70, 100 and130 m, respectively.

In urban areas, it may not be possible to providethe deceleration lengths and maintain the storageand approach taper lengths required. In thesesituations, these lengths should be used as adesirable goal.

Storage Length - The storage length should besufficient:

• To store the number of vehicles duringcritical periods.

• To avoid left-turning vehicles stopping in thethrough lanes.

• So the lane entrance is not blocked bystanding through traffic.

Refer to the “Highway Capacity Manual, SpecialReport No. 209”, Transportation ResearchBoard, 1986 for further discussion.


Part 2 400-14

406.05 RIGHT-TURNCHANNELIZATION

General - Right-turn lanes improve intersectioncapacity and safety. As for left-turn lanes, right-turn lanes should be laid out such that a right-turning vehicle must make a definite move toenter the lane.

The desirable length of the right-turn lane is thesum of storage requirements and decelerationlength, including bay taper.

Width - The desirable right-turn lane widthshould be 3.65 m. Three meter wide right-turnlanes may be used on low speed urban roadways.The width is measured from the adjacent edge oftravelled way, excluding shy distance.

The normal shoulder should be provided at theright-turn lane although, if right of way isseverely constrained, a minimum 1.2 m wideshoulder may be used. The normal curb should becarried through the right-turn section.

Approach Tapers - Generally right-turn laneapproach tapers are not required because the laneis added to the outside of the travelled way andthe travel lanes are not shifted. However, if thetravel lanes must be shifted to accommodate aright-turn lane, the taper should be the same asfor left-turn lanes.

Bay Tapers - The bay taper which guides themotorist into the right-turn lane is a straight linealong the right edge of the travelled way.Generally the taper length should be 15:1.

Deceleration Length - Whenever feasible, theright-turn lane should provide deceleration clearof the through lanes. The minimum decelerationlengths, exclusive of bay taper and vehiclestorage, for 50, 60 and 80 kph are 70, 100 and130 m, respectively.

In urban areas, it may not be possible to providethe deceleration lengths and maintain the storageand approach taper lengths required. In thesesituations, these lengths should be used as adesirable goal.

Storage Length - Storage requirements and goalsare the same as for left-turns.

Free Right-Turns - Uncontrolled “free” right-turns improve capacity of an intersection with aheavy right-turn demand. The right-turn is made"free" by channelizing the turning movementoutside of the intersection controls. Free right-turns shall only be provided where the turningmovement can be made into an auxiliary oracceleration lane.

406.06 TRAFFIC ISLANDS

General - Traffic islands are located betweentraffic lanes and are commonly designated usingpaint, raised pavement markers, or curbs. Theyserve to:

• confine specific traffic movements intodefinite channels;

• separate traffic moving in the same oropposite direction;

• aid and protect pedestrians crossing theintersection; and,

• discourage or prohibit undesirablemovements.

Design - Traffic islands must be large enough tobe seen and to command the attention of thedriver. Islands for channelizing should preferablybe at least 9.0 m2. Curbed islands for separatingtraffic streams should not be less than 1.0 m wideand 8.0 m long.

Curbed islands should be offset from the throughtraffic lanes by a minimum shy distance of 0.6 mand 0.9 m is preferable for approach speedsgreater than 25 kph.

The approach end of a curbed island should berounded at 0.5 to 1.0 m radius and tapered at 15:1to guide the driver into the channelization.

Where there is an approach shoulder (1.2 m orwider), the curbed island should be offset fromthe through lane by the width of the shoulder.With an approach shoulder the flared approach isnot necessary, except where a deceleration orturning lane has been provided.


Part 2 400-15

Avoid curbed traffic islands where the approachoperating speeds are 80 kph or greater.Mountable curbs should be used at curbed islandsexcept where barrier curbs are provided forgreater pedestrian protection.

407 ROUNDABOUT DESIGN

There are three main types of roundabouts,Normal, Mini and Double. There are other formsof roundabouts but they variations of these basictypes. They are Ring Junctions, Grade Separatedand Signalized Roundabouts. More informationabout the use and design of these and otherroundabouts can be found in the GeometricDesign of Roundabouts. When reading thisdesign manual the designer should be aware thatthe manual was written for left-hand runningtraffic and appropriate modifications should bemade for when adapting these standards to right-hand running traffic patterns.

The roundabout is used at intersecting streets withlow capacity and low design speed. Roundaboutsshould be considered when they are cost effectiveor increase safety over standard intersectiondesigns.

Advantages: There are several advantages toroundabout design versus conventional three andfour leg intersections.• Roundabouts are more efficient than signals

on balanced traffic demand intersections.• Roundabouts allow for continuous traffic

flow.• Roundabouts can reduce traffic speeds in

existing intersections.

Disadvantages: There are several disadvantagesto roundabouts that make them less favorablethan conventional designs.• Driver comprehension to right-of-way with

respect to yielding to traffic flow.• Roundabouts are prone to large congestion

problems when traffic exceeds designcapacity.

• It is difficult to redesign an existingroundabout to increase its capacity. Redesignrequires adding more lanes which greatlyincreases the land required for theintersection. This increase in diameter alsoincreases the design speed through the

roundabout. For these reasons roundaboutstend to be removed and replaced withconventional signalized intersections insteadof being modified.

• Roundabouts require more land thanconventional intersections.

• Roundabouts are not well suited forpedestrian traffic, because pedestrians are notable to walk in a clear path through theintersection. In areas of high pedestriantraffic, pedestrians can cause major problemswith illegal crossings.

Normal Roundabouts: The normalconfiguration of a roundabout is made up of aone-way road around a circular curbed island 4mor more in diameter. The approaches are usuallyflared to allow multiple vehicle entries. Thenumber of entries should be limited to three orfour arms. The efficiency and drivercomprehension decreases as the number of armsis increased. The minimum radius of curvaturealso increases with additional arms which canraise circulatory speeds. Double roundabouts canbe an alternative under these conditions. SeeFigure 400.08.

Figure 400.08Normal Roundabout

Mini Roundabouts: The mini-roundabout issimilar to the normal roundabout except thediameter of the island is less than 4m. Instead ofa curbed island a raised, reflectorized dome isused for driver recognition of the high spot. Themini-roundabout is a good alternative for existingroads with extremely low traffic volumes thathave high safety and delay problems. Wherephysical deflection of approaching traffic is not


Part 2 400-16

possible, roadway stripping and traffic islandsmay be used. See Figure 400.09.

Figure 400.09Mini Roundabout

Double Roundabouts: Double roundabouts aregenerally used in areas with unique trafficrequirements such as:• Where intersection improvements are done

and the roundabout eliminates the need torealign an approach road.

• In areas where more than four arms areentering the intersection.

• At intersections with unusual or asymmetricalconfigurations.

• Where single island configurations do nothave enough capacity.

• The joining of parallel roads separated by anexisting feature.

These unique circumstances should be evaluatedby an experienced traffic engineer and theMunicipality must be informed on the decision toconsider a double roundabout. The doubleroundabout should only be used after properconsideration and is contingent only with theapproval of experienced personnel and theMunicipality. See Figure 400.10.

Figure 400.10Double Roundabout


Part 2 500-1

SECTION 500INTERCHANGES

501 GENERAL

The ability to accommodate high traffic volumessafely and efficiently through intersectionsdepends on how intersecting traffic is handled.The greatest efficiency, safety, and capacity areattained when intersecting through traffic lanesare physically separated. An interchange doesthis with a combination of ramps and gradeseparations at the junction of two or moreroadways. This reduces or eliminates trafficconflicts, improves safety, and increases trafficcapacity. Crossing conflicts are eliminated bygrade separations and turning conflicts areeliminated or minimized depending on theinterchange configuration.

The selection and design of grade separationsand interchanges is influenced by roadwayclassification, traffic volume, traffic composition,design speed, access control, signingrequirements, economics, terrain, right-of-way,capacity and safety. Interchange types varywidely so each site should be studied andalternate concepts made to determine theappropriate layout.

502 INTERCHANGE WARRANTS

Interchanges are very costly and should be usedonly where necessary. Interchanges should beconsidered based on the following warrants:

• Where intersecting traffic volumes areheavy.

• Where topography does not lend itself to theconstruction of an intersection.

• When making a connection to a freeway.• For a roadway with access control between

selected terminals.• To eliminate a traffic bottleneck.• To eliminate a hazardous at-grade

intersection.• When road-user benefits are substantial.

503 DESIGN CONSIDERATIONS

Due to the complex nature of interchange designit is important to establish a set of consistentdesign parameters. Listed below are featureswhich should be considered during theinterchange design process.

• Provide consistent design features.• Ramp exits shall be from the right.• Ramp entrances shall be on the right.• One exit per direction from main roadway.• Ramp design speed beyond exit should

preferably be one-half to two-thirds that ofthe roadway.

• Provide ramps for return or complementarytraffic movements at same interchange.

• Use grades and slopes as flat as possible.• Consider signing during geometric design.

504 INTERCHANGE TYPES

This section includes examples of commonlyused interchange configurations. See Chapter Xof "A Policy on Geometric Design of Highwaysand Streets," AASHTO, 1994, for additionalexamples.

504.01 THREE-LEG INTERCHANGE

Three-leg interchanges have three intersectinglegs. They usually consist of one or moreroadway grade separations and one-wayroadways for all traffic movements. Becausefuture expansion is difficult, three-leginterchanges should only be used when one ofthe three legs is permanently terminated. Heavytraffic volume should be favored with moredirect alignments, and lesser volumes can belooped. Skewed crossings are desirable becausetravel distance is less, the turning radius is flatterfor the heavier left-turning volume and there isless angle of turn for both left turns.

Figure 500.01 illustrates several types of threeleg interchanges.


Part 2 500-2

Figure -500.01Three-Leg Interchanges

From AASHTO, 1994," A Policy on Geometric Design of Highways and Streets".


Part 2 500-3

504.02 FOUR-LEG INTERCHANGES

Four-leg interchanges include diamondinterchanges, full cloverleaves, partialcloverleaves (parclo), and interchanges withdirect and semidirect connections. Each basicinterchange type is described and discussed inthe following sections.

Diamond Interchange

Diamond interchanges are the most commonlyused interchange (Figure 500.02). They consistof four ramps which parallel the main roadway,providing all eight turning movements.

Figure 500.02Simple Diamond

Application - The diamond is used atmajor/minor roadway crossings with direct highspeed exit/entrance ramps on the major roadwayand at-grade intersections on the minor roadway.

It is adaptable to a wide range of traffic volumesand capacity may be increased by widening theramps and cross road in the intersection area byproviding storage lanes, two-lane left turns,channelization, and traffic signals at the rampcross road intersections.

Advantages -• High design standard single exits in advance

of the structure.• High design standard single entrances

beyond the structure.• Requires relatively little right-of-way.

• Comparatively low construction cost.• Direct cross road turning maneuvers.• Single exit feature simplifies expressway

signing.• No need for speed change lanes on or under

the structure.• No weaving on the expressway.

Disadvantages -• Overall capacity is limited by ramp

intersection capacity.• Capacity is lowered on the minor road due

to left turning movements.• Increased accident potential unless

signalized.• Possibility of wrong-way movements.• Turning traffic from the expressway is

obliged to stop at the minor road. Storagelane treatment may be required.

• Little possibility for future expansion.

Single Point Diamond InterchangeThe Single Point Interchange (SPI) is also knownas an urban interchange or a single pointdiamond interchange (Figure 500.03). All fourturning movements are controlled by a singletraffic signal and opposing left turns cross to theleft of each other.

Figure 500.03Single Point Diamond Interchange


Part 2 500-4

Application - Best suited for areas where right-of-way is restricted.

Advantages• Relatively narrow right-of-way.• Opposing left turns pass to the left of each

other.• Traffic signal is three-phase rather than four.• Operates with a single traffic signal reducing

delay through the ramp intersection.• Handles high volume left-turns on the cross

road more efficiently than a diamond.• Curve radii for left-turn movements through

the intersection are significantly flatter thanat conventional intersections, and thereforethe left turns move at higher speeds.

• Higher capacity than a conventional tightdiamond interchange.

Disadvantages -• Higher construction cost than a conventional

tight diamond interchange.• Extensive retaining walls required where

right-of-way is restricted.• Vehicle path through the intersection

requires, at a minimum, a painted guidancestripe.

• Not suitable for skewed interchanges.• Adding pedestrian movement to the

interchange adds a signal phase and reducesefficiency.

Cloverleaf

The cloverleaf is a four-leg interchange that usesloop ramps to eliminate the four left-turnmovements and uses outer ramps for the fourright-turn movements (Figure 500.04). Aninterchange with loops in all quadrants is referredto as "full cloverleaf" and all others as a "partialcloverleaf (parclo)".

Application - Where there is a need to avoidrestrictive at-grade left turns and adequate rightof way is available.

Figure 500.04Cloverleaf

Advantages -• Left-turn conflicts eliminated• Single structure design.• Traffic signals are unnecessary.• Lends itself to stage construction.

Disadvantages -• Large right-of-way requirements.• Weaving may severely limit capacity.• Adding weaving lanes on and under structure

increase cost.• High weave volumes require collector

distributor roads.• Double exit on the expressway complicates

signing.• Insufficient deceleration length from

expressway speed to control speed of innerloop.

• Poor safety features.• Extra travel distance/time required for left

turns.• Large trucks may experience problems with

tight curves.


Part 2 500-5

Cloverleaf with Collector Distributor Road

A collector distributor road in conjunction with acloverleaf removes the weaving ramp trafficfrom the main roadway (Figure 500.05).

Figure 500.05Cloverleaf with Collector Distributor Road

Application - Same as for basic cloverleaf exceptis more suitable for areas with high weavingvolumes.

Advantages -• Minimizes weaving conflicts by placing

weave on collector distributor road.• Minimizes signing difficulties.• Provides a single exit and entrance from

main roadway.• Reduce merging and diverging points on

main roadway.• Higher volume than basic cloverleaf design.

Disadvantages -• May require more right of way than basic

cloverleaf.• Higher structure costs than basic cloverleaf

due to greater span.• Signing is more complicated than basic

clover leaf

Partial Cloverleaf (Parclo)

A partial clover leaf is a portion of the full cloverleaf design. Ramps should be arranged so that theentrance and exit turning movements create theleast impediment to major roadway traffic flows.The general parclo interchange applications,advantages and disadvantages are given below.Figures 500.06 through 500.10 show severalparclo arrangements and lists their relativeadvantages and disadvantages.

Application - This interchange is suitable forlocations where by removing two left-turnmovements from the intersections the remainingleft-turn conflicts can be tolerated.

General Advantages -• Suitable for stage construction.• Exit terminals in advance of structure.• Weaving eliminated.• Single exit simplifies signing.• Expandable if structure opening wide

enough.• Can be configured to optimize traffic

volume/capacity.• Future expansion if structure opening wide

enough.

General Disadvantages -• Minor road has stop condition for left-turn.• Minor road may require left-turn storage.• Points of conflict on the minor roadway at

the ramp terminals limit capacity and safety.• Right-turn expressway traffic stops at minor

roadway.


Part 2 500-6

Figure 500.06

Advantages -• Entrance ramp loops.Disadvantages -• Stop condition on minor road and ramps for

left turns.

Figure 500.07

Advantages -• Stop for left-turns confined to movements

from ramps only.• Entrance ramp loops.

Figure 500.08

Disadvantages -• Stop condition on minor road and ramps for

left turns.• Expressway traffic exits onto small radius

loop.• Entrance/exit loops

Figure 500.09

Disadvantages -• Stop condition on minor road and ramps for

left turns.• Expressway traffic exits onto small radius

loop.

Figure 500.10

Advantages -• Stop condition for left turns confined to

movements from minor roadway only.• Not conducive to wrong-way movements.

Disadvantages -• Expressway traffic exits onto small radius

loop.

Directional Interchanges

A direct connection is defined as a one-wayroadway that does not deviate greatly from -theintended direction of travel. Interchanges thatuse direct connections for the major left-turnmovements are termed directional interchanges(Figure 500.11). Direct connections for one orall left-turn movements would qualify aninterchange to be termed directional even if theminor left turn movements are accommodated onloops.


Part 2 500-7

Directional interchanges have one or more gradeseparations with direct or semidirect rampconnections for one or more left turningmovements. Free flow is provided for highturning traffic volumes in one or two quadrantscomparable in volume to through traffic.

When one or more interchange connections areindirect in alignment yet more direct than loops,the interchange is described as semi-directional.All left-turn connections or only those thataccommodate major left-turn movements may besemi-direct in alignment.

The most widely used type of directionalinterchange is the four-level layout systemshown in Figure 500.11A. A variation of thistype is the four-level interchange with two exitsfrom both major roadways, as shown in Figure500.11B.

Chapter X of "A Policy on Geometric Design ofHighways and Streets," AASHTO, 1994, hasadditional examples of directional interchanges.

Application - Semi-direct or direct connectionsfor one or more left-turning movements are oftenrequired at major interchanges in urban areas.Interchanges involving two freeways nearlyalways call for directional layouts. In such casesturning movements in one or two quadrants oftenare comparable in volume to throughmovements.

Advantages -• Reduced travel distance.• Increased speed and capacity.• Weaving eliminated.• Avoids the indirection in driving on a loop.• Higher levels of service .• Require little right of way.

Figure 500.11Directional Interchanges

Disadvantages -• High construction costs.• Require detailed, time-consuming study.


Part 2 500-8

505 INTERCHANGE DESIGNPROCEDURES

General - Since interchanges are so costly, and avital element of freeway capacity it is importantthat a well functioning, economic design beconceived. In general, alternative interchangeschemes should be analyzed and severalpreferred alternatives should be selected basedon geometry, capacity, signing, aesthetics,environmental compatibility, overall adaptability,route continuity, route uniformity, maintainingtraffic during construction, suitability to stageconstruction, right-of-way requirements and theeffect on the local road and roadway network.

From these preferred alternatives, preliminaryplans, profiles and cost estimates should beprepared. Include costs for right-of way,construction, maintenance, and other appropriateitems. Once this data has been prepared, the bestinterchange design concept can be selected.

506 INTERCHANGE DESIGNSTANDARDS

An interchange consists of the through freeway,the ramps and the cross road. This section dealsprimarily with the interchange as a whole.Specific designs for ramps are discussed in thesections that follow.

Sight Distance - Stopping sight distance shall bethe minimum sight distance provided on therespective roadways through an interchange andpreferably longer. Decision sight distance shallbe provided at exits. Sight distance requirementsare discussed in Part 2, Section 300, GeometricCross Section.

For minimum radius curves, the normal lateralclearance may not provide minimum stoppingsight distance because piers, abutments andbridge rail limit horizontal sight distance. If aflatter curve cannot be used, the clearancesshould be increased to obtain the proper sightdistance even though it is necessary to increasestructure spans or widths.

Design Speed Considerations - In the design ofinterchanges it is important to provide verticaland horizontal alignment standards which are

consistent with the design speed for the roadwaysand driving conditions expected.

Spacing - Minimum interchange spacing isdetermined by weaving volumes, ability to sign,signal progression, and required lengths of speedchange lanes. Interchange spacing has apronounced effect on freeway operation. Ingeneral, minimum spacing shall be:

Rural Urban3.0 km 1.5 km

Uniformity - To the extent practicable allinterchanges along a freeway should be uniformin geometric layout and general appearance. Allentrance and exit ramps shall be on the right.

Signing and Marking - Signs, pavementstriping, delineators and other markings shouldconform to the Manual on Uniform TrafficControl Devices (MUTCD).

Basic Number of Lanes - Design trafficvolumes and a capacity analysis should be usedto determine the basic number of roadway lanesand the minimum number of ramp lanes. Thebasic number of lanes should be established for asubstantial length of freeway and should not bechanged through pairs of interchanges.

Auxiliary Lanes - An auxiliary lane is definedas the portion of the roadway adjoining thetravelled way for emergency stopping, speedchange, turning, turning storage, weaving, truckclimbing, and other purposes supplementary tothrough-traffic movement.

An auxiliary lane may be needed when:• interchanges are closely spaced.• the distance between the end of the taper on

the entrance terminal and the beginning ofthe taper on the exit terminal is short.

• local frontage roads do not exist.• necessary for lane balance.• necessary for capacity requirements.• necessary for weaving.

An auxiliary lane may be introduced as a singleexclusive lane or in conjunction with a two-laneentrance. Auxiliary lanes may be dropped in asingle or two-lane exit or carried to the physicalgore nose before tapering into the through


Part 2 500-9

roadway. Auxiliary lanes may be tapered orparallel and shall be a minimum of 3.65 m wide.

Lane Reduction - The basic number of freewaylanes may be reduced if the exit volume is largeenough to change the basic number of lanesrequired beyond the reduction point for thefreeway as a whole.

The reduction may be made at a two-lane exitramp or between interchanges. The lane-droptaper should be on a horizontal tangent on theapproach side of a crest vertical curve, or on asag vertical curve. The lane reduction shall bemade on the right using a desirable taper rate of70:1 (minimum taper rate of 50:1).

Weaving Sections - Weaving sections areroadway segments where vehicles entering andleaving at adjacent access points cross eachothers paths. Weaving sections reduceinterchange capacity and should be eliminatedfrom the main facility where feasible. Refer tothe Highway Capacity Manual for furtherdiscussion on weaving sections.

507 RAMP DESIGN STANDARDS

General - A ramp is typically a one-wayroadway connecting interchange legs. Rampsconsist of three main parts. The ramp freewayentrance or exit, the ramp body and the rampintersection with the cross road. The intersectionwith the freeway is called the ramp entrance orexit and the intersection with the cross roads istypically defined as the ramp terminal.

This section deals mainly with general rampdesign criteria. Specific ramp entrance/exit andterminal designs are discussed separately in thefollowing sections.

Design Speed - Ramp design speed varies basedon location along the ramp. The freewayentrance or exit design speed approximates thefreeway design speed. The ramp terminal designspeed usually approximates that of the cross roadif there is no stop condition. The design speedfor the ramp body transitions from the freewaydesign speed to the terminal design speed. Seetypical examples in Table 500.01.

Table 500.01Ramp Entrance/Exit Design Speed

Freeway Design Speed Ramp Design Speedkph kph140 100120 85100 70

These speeds do not apply to ramp terminals,which should be designed using the intersectingroadway speed.

Profile - A typical ramp profile consists of theramp body on an appreciable grade, betweenvertical curves that connect to the intersectionlegs. The profile at the ramp terminal isgenerally determined by the cross road.

Ramp grades should be as flat as feasible. Downgrades should be limited to 3 or 4 percent onramps with sharp horizontal curvature andsignificant heavy truck or bus traffic. However,sight distance is more important than a specificgradient control and should be favored in design.As general criteria, it is desirable that ascendinggradients on ramps be limited to:

Table 500.02Ramp Grades

Ramp RampDesign Speed Gradient

kph %70-80 3-5

60 4-640-50 5-730-40 6-8

Curvature - The factors and assumptions ofminimum-turning roadway curves for variousspeeds apply to ramps and are discussed inSection 200.

Sight Distance - The minimum sight distanceprovided anywhere along the ramp shall bestopping sight distance. See the sections onfreeway entrance/exit ramp and ramp terminalsfor specific requirements at those areas.

Shoulder Width - Shoulder widths for rampsshall be as indicated in Part 2, Section 300,Geometric Cross Section.


Part 2 500-10

Gores - The term "gore" indicates an areadownstream from the shoulder intersection pointsas illustrated in Figure 500.12. The gore nose isdefined as that point where the distancemeasured between the main line and ramptravelled ways is 7.0 m. If feasible, the unpavedarea beyond the nose should be graded level withthe roadways. Heavy sign supports, street lights,and roadway structure supports shall be kept outof the graded gore area.

Profile grade considerations are of particularconcern through entrance and exit gore areas. Insome instances the ramp profile, or thecombination of profile and cross slope, issufficiently different from the freeway throughlanes that grade breaks across the gore becomenecessary. Where adjacent lanes or lanes andgore areas at freeway entrances and exits are notin the same plane, the algebraic difference inpavement cross slope shall not exceed 5%.

Lane Drops - Typically the ramp lane reductionshall be made using a desirable taper rate of 70:1,50:1 maximum.

Lane drop tapers should not extend beyond the 2meter point (the beginning of the weavinglength) without the provision of an auxiliarylane.

Lane Additions - Lane additions to ramps shalluse a taper rate of 10:1.

Superelevation And Cross Slope - The factorscontrolling superelevation rates discussed in Part2, Section 200, Geometric Design Standards,apply to ramps. Ramp superelevation rates shallbe per Table 200.04.

Where feasible, the curve radius should beincreased to reduce the required standardsuperelevation rate. Both the edge of travelledway and the edge of shoulder should beexamined at ramp junctions to assure a smoothtransition.

Figure 500.12Typical Gore Area



Part 2 500-11

Widening - Where ramps have curve radii of 90m or less with a central angle greater than 60degrees the lane furthest to the right of the ramp,shall be widened in accordance with Table500.03 in order to accommodate large truckwheel paths. More than one lane may bewidened if warranted by truck and bus usage.

Table 500.03Ramp Widening For Trucks

Ramp Radius Widening Lane Width(m) (m) (m)

<40 2.0 5.640 - 44 1.6 5.245 - 54 1.3 4.955 - 64 0.9 4.565 - 74 0.6 4.275 - 90 0.3 3.9

>90 0 3.6

For ramps having curve radii of 90 m or lesswith a central angle greater than 60 degrees.

Normally, loop ramps are one lane unlesscapacity warrants additional lanes.Consideration should be given to providing adirectional ramp when loop volumes exceed1500 vehicles per hour. If multiple lanes areprovided, normally only the right lane needs tobe widened.

Loop Ramps - Radii for loop ramps shouldnormally range from 45 m to 60 m. Increasingthe radii beyond 60 m is typically not costeffective as the slight increase in design speed isusually outweighed by the increased right of wayrequirements and the increased travel distance.For roadway design speeds greater than 80 kphthe loop design speed should not be less than 40kph (45 m radius). Extremely tight curves (lessthan 35 m radii) should be avoided because theylead to increased off-tracking and increase thepotential for vehicles to enter the curve withexcessive speed. See Table 200.05 for furtherguidelines on radius versus design speed.

Research indicates that trucks often enter loopswith excessive speed, either due to inadequatedeceleration on exit ramps or due to driverefforts to maintain speed on entrance ramps to

facilitate acceleration and merging. Where theloop ramp has a small radius on a steep descent(over 6%), it is important to develop the standard2/3 full superelevation rate by the beginning ofthe curve. On loop entrance ramps this can oftenbe facilitated by beginning the ramp with a shorttangent (20 m to 30 m) that diverges from thecross street at an angle of 4 to 9 degrees. Longertangents are desirable.

Distance Between Successive On-Ramps - Theminimum distance between two successivefreeway on-ramps should be the distance neededto provide the standard on-ramp accelerationtaper shown on Figure 500.13. This distanceshould be about 300 m. If the upstream rampadds an auxiliary lane, the downstream rampshould merge with the auxiliary lane. Thedistance between on-ramp noses will then becontrolled by interchange geometry.

Distance Between Successive Exits - Theminimum distance between successive exitramps for guide signing should be 300 m on thefreeway and 180 m on collector-distributor roads.

508 ENTRANCE/ EXIT RAMPDESIGN STANDARDS

General - The ramp entrance/exit is that rampportion adjacent to the through travelled way,including speed-change lanes, tapers, andislands. All freeway entrances and exits shallconnect to the right of through traffic. Thefollowing paragraphs discuss various designelements of ramp entrances/exits.

Entrance/Exit Sight Distance - Decision sightdistance is desirable along the freeway prior toan exit nose and the entire exit terminal shouldbe visible.

When an exit must be located where visibility islimited by physical restrictions which cannot becorrected by cut widening or object removal, anauxiliary lane in advance of the exit should beprovided. The minimum length of auxiliary laneshall be 300 m desirable, 180 m minimum.


Part 2 500-12

Figure 500.13Single Lane Freeway Entrances and Exits

From Caltrans, 1995, Highway Design Manual


Part 2 500-13

Exit Design Speed - The minimum design speedat the exit nose should be 80 kph or greater forboth ramps and branch connections. Decisionsight distance should be provided at freewayexits and branch connectors.

Entrance Design Speed - The design speed atthe nose should be consistent with approachalignment standards. If the approach is a branchconnection or diamond ramp with high alignmentstandards, the minimum design speed should be80 kph.

Entrance/Exit Designs - Design of freewayentrances and exits should conform to thestandard designs in Figures 500.13, 500.14, and500.15 for single lane, two lane entrances andexits, and diverging branch connections,respectively. A branch connection is defined as amultilane connection between two freeways.

The minimum deceleration length shown onFigure 500.13 shall be provided prior to the firstcurve beyond the exit nose. This provides foradequate deceleration before entering the curve.When the subsequent curve is a descending loopor hook ramp, or if the upstream condition is asustained downgrade, deceleration length shouldbe increased. (see AASHTO, “A Policy onGeometric Design of Highways and Streets”,1994, Chap. X for additional information).

Single-lane Freeway to Freeway ConnectionsFreeway-to-freeway connectors may be singlelane or multilane. Where design year volume isbetween 900 and 1500 equivalent passenger carsper hour, initial construction should provide asingle lane connection with the capability ofadding an additional lane. Single lane directionalconnectors should be designed using the generalconfigurations shown on Figure 500.13, bututilizing the flatter diverge angle shown in Figure500.15. Single lane loop connectors may use adiverge angle of as much as that shown on Figure500.13 for ramps, if necessary. The choice willdepend upon interchange configuration anddriver expectancy. Single-lane connectors inexcess of 300 m in length should be widened totwo lanes to provide for passing maneuvers.

Two-Lane Exit Ramps - Where design yearestimated volumes exceed 1500 equivalentpassenger cars per hour, a 2-lane exit per Figure500.14 should be used. A minimum 400 mauxiliary lane should be provided in advance of atwo-lane exit. Provisions should also be madefor widening to three or more lanes at the crossroad intersection.

For volumes less than 1500 but more than 900, aone-lane width exit ramp should be providedwith provision for adding an auxiliary lane andan additional lane on the ramp.

Branch Connections - A branch connectionshould be provided when the design year volumeexceeds 1500 equivalent passenger cars per hour.

Merging branch connections should be designedas shown in Figure 500.14. Diverging branchconnections should be designed as shown inFigure 500.15. The standard ramp exit connectsto a local street. The diverging branchconnection connects to another freeway and has aflatter angle that allows a higher departure speed.

At a branch merge, an 800 m length of auxiliarylane should be provided beyond the merge of onelane of the inlet, except where it does not appearthat capacity on the freeway will be reached untilfive or more years after the 20 year designperiod. In this case the length of auxiliary laneshould be a minimum of 300 m. For divergingconnections where less than capacity conditionsbeyond the design year are anticipated, the lengthof auxiliary lane in advance of the exit should be400 m.

Branch Lane Drops - The lane drop taper on afreeway-to-freeway connector shall not be lessthan 70:1.


Part 2 500-14

Figure 500.14Two-Lane Entrance and Exit Ramps



Part 2 500-15

Figure 500.15Diverging Branch Connections



Part 2 500-16

Two-Lane Entrance Ramps - A standard twolane entrance ramp is illustrated in Figure500.14. This design may be utilized in situationswhere the estimated design year volume exceeds1500 equivalent passenger cars per hour. Figure500.14 includes a minimum 300 m auxiliary laneparallel to the freeway, which is only used whereadequate design year capacity exists on thethrough facility. If capacity is inadequate,consideration should be given to extending theauxiliary lane to the next interchange or addingadditional freeway through lanes. For mosturban situations, it is recommended that multipleramp lanes taper to a single lane prior to the 2-meter separation point (where merging isconsidered to begin).

Entrance/Exit Locations - Freeway entrancesand exits should be located on tangent sectionswherever possible. This provides maximumsight distance and optimum traffic operation.

Where it is necessary to locate entrances/exits ona curve, the ramp entrances and exit tapersshould also be curved. The exit taper radiusshould approximate the freeway edge of travelledway in order to develop the standard degree ofdivergence (Figure 500.16).

Figure 500.16Curved Entrance/Exit Locations


On curved entrance ramps the distance from theinlet nose (4.25 m point) to the end of theacceleration lane taper should equal the sum ofthe distances shown on Figure 500.13 The 50:1taper may be curved to fit the conditions, and the1000 m radius curve may be adjusted.

Entrance/ Exit Grades - Grades for freewayentrances and exits are controlled primarily bysight distance requirements. Ramp profile gradesshould not exceed 6%.

Exit Profiles - Vertical curves located justbeyond the exit nose should be designed with aminimum 80 kph stopping sight distance.Beyond this point, progressively lower designspeeds may be used to accommodate loop rampsand other geometric features.

Entrance Profiles - Entrance profiles shouldapproximately parallel the freeway profile for atleast 30 m prior to the inlet nose to provideintervisibility in merging situations. The verticalcurve at the inlet nose should be consistent withapproach alignment standards.

Where large-truck volumes exceed 20 vehiclesper hour on ascending entrance ramps withsustained upgrades exceeding 2%, a minimum450 m long auxiliary lane should be provided toinsure satisfactory separating conditions.

Exit Ramp Transitions - Exit ramps in urbanareas may require additional lanes at the crossroad intersection to provide storage and increasecapacity.

If the length of a single lane ramp exceeds 300m, an additional lane should be provided on theramp to permit passing maneuvers.

508.01 RAMP TERMINAL DESIGN

The ramp terminal is defined as the area wherethe ramp meets the cross road.

Terminals - Ramp terminals should be treated asat-grade intersections. The terminal design shallbe per Part 2, Section 400, At-GradeIntersections, based on near-minimum turningconditions.

Terminal Grades - Ascending off-ramps shouldjoin the cross roads on a reasonably flat grade toexpedite truck starts from a stopped condition.Ramp terminals should connect where the grade


Part 2 500-17

of the over crossing is 4% or less to avoidpotential overturning of trucks.

Terminal Locations - Factors which influencethe location of ramp terminals include sightdistance, construction costs, right of way costs,circuitry of travel for left-turn movements,crossroads gradient at ramp intersections, storagerequirements for left-turn movements off thecrossroads, and the proximity of other local roadintersections.

Where a separate right turn lane is provided atramp terminals the turn lane should not continueas a "free" right unless pedestrian volumes arelow, the right turn lane continues as a separatefull width lane for at least 60 m prior to merging,and access control is maintained for at least 60 mpast the ramp intersection. Provision of the"free" right should also be precluded if left turn

movements are allowed within 125 m of theramp intersection.

Terminal Sight Distances Horizontal sightrestrictions may be caused by bridge railings,bridge piers, or slopes. Sight distance ismeasured between the center of the outside laneapproaching the ramp and the eye of the driver ofthe ramp vehicle assumed 3.0 m back from theedge of shoulder at the crossroads. Figure500.17 illustrates ramp setback from an overcrossing structure. This figure is based on sightdistance being controlled by the bridge rail, butthe same relationship exists for sight distancecontrolled by bridge piers or slopes.

Where ramp set back is unobtainable, sightdistance shall be provided by flaring the end ofthe overcrossing structures or setting back thepiers or end slopes of an undercrossing structure.

Figure 500.17Ramp Setback



Part 2 600-1

SECTION 600GEOTECHNICAL ENGINEERING

601 INTRODUCTION

The first part of this section is intended to give anoverview of what is required in a geotechnicalreport used for roadway and structural design. Itdoes not cover the specific methods of testing,sampling or analysis required. Standard SIpractices and the “Municipality Roads SectionGuidelines for Subsurface Investigations for CivilEngineering Purposes” current revision should beused for guidance in this area.

The second part of this section outlines thepavement design procedure.

602 GENERAL

The Consultant shall obtain approval from theRoad Section, Traffic Police and any otherconcerned Agencies prior to commencing ageotechnical investigation.

Generally a geotechnical investigation is carriedout in two phases. The initial phase consists ofpreliminary drilling and testing to gather enoughproject specific information to advance theroadway and structure design. The final stage, ifrequired, is performed for design featuresrequiring specific geotechnical recommendations.

603 GEOTECHNICAL REPORT

Once the preliminary horizontal and verticalalignment and structure locations have beendefined, the engineer will prepare a preliminary asubsurface exploration and testing program.Providing information such as foundation types,safe slope angles and preliminary pavementthickness allows the initial design to be advancedand refined. The initial program also identifiesthe type, severity and extent of any geotechnicaldesign problems.

The geotechnical report should consist of resultsand recommendations from the initial drilling andtesting program as well as any information fromprior investigations. Prior investigations and data

may be obtained through the Abu DhabiMunicipality Road Section as well as otherMunicipality and Government Agencies.

The geotechnical report is to contain theinformation shown in Table 600.01 as aminimum.

Table 600.01GEOTECHNICAL REPORT

Table of Contents

• Introduction• Location Map• Proposed Construction• Previous Information and/or Investigations• Field Investigation And Laboratory Testing• Include Boring Location Plan• Site and Subsurface Conditions• Climate• Significant Geotechnical Features• Regional Geology and Seismicity• Analysis and Recommendations• Retaining Wall Recommendations• Excavation and Ground Compaction

Factors• Expected Settlements• Groundwater Observations• Allowable Foundation Loads• Foundation Recommendations• Borrow/Material Source• Slope Stability• Soil Corrosivity to Buried Structures• Subgrade Support for Pavement Design• Topsoil Plating Recommendations• Treatment for Problem Soils• Any Relevant Geotechnical Aspects

Affecting Future Performance of theWorks

• Appendices• Boring Logs• Summary of Test Results• Other Pertinent Information

Pertinent information should be included in theappendices. In certain circumstances, such as amajor bridge design or other major structure, anadditional report may be required to define specialgeotechnical aspects of foundation design.


Part 2 600-2

604 STRUCTURAL PAVEMENTSECTION DESIGN

604.01 GENERAL

604.01.01 Pavement Design Methods

Pavement design is a challenging process becausethe analytical framework for design is socomplex. Complexity is introduced both by thenumber of materials involved and the number ofvariables required for design. The pavementsection itself consists of a surfacing material andseveral supporting layers. The strengths andmoduli of these layers vary through several ordersof magnitude, and at least the lowest layer (nativesubgrade) is best described by non-linearconstitutive models. These factors by themselvesmake development of equations which controleven simple material behaviors such as deflectionunder load extremely non-trivial.

The problem is exacerbated by the sheer numberof variables which ought to be considered. Thepavement is influenced by the soil upon which thepavement is supported, the number of vehiclesexpected to pass over the pavement, the weight ofthe vehicles which pass over, the spatialarrangement of the tires which support thatweight, the tire pressure, the material propertiesof the pavement section materials, the temperatureand temperature range, the moisture condition ofthe subgrade, the likelihood of freeze-and-thawcycles, and probably several more. Many of thesevariables are extremely difficult to evaluate. Thesoil conditions under the pavement is evaluated atonly a few points, and the weakest points arestatistically likely to be missed. Trafficpredictions are notoriously complicated andinaccurate. Furthermore, pavement failure is verydifficult to define, as there are many possiblefailure modes. The analytical process underlyingeach failure mode is different.

Generally speaking, there is a spectrum of designapproaches which could be taken, ranging frompolar extremes of purely analytical methods topurely phenomenological methods.

The advantage of the phenomenological approachis that one does not need to spend resources onmeasurement of input variables. The advantageof the analytical approach, however, is thatconditions outside the experience of the designercan be designed for by selecting the appropriateinput variables.

Actual pavement design methods fall somewherebetween these two extremes. Field and laboratoryinvestigation of pavement properties andperformance over the last 20 to 30 years have ledto semi-analytical methods based on observations.The many input variables are introduced eitherthrough equations developed by regression orequations developed from first principles.

The TRIP pavement design method was based onthe interim AASHTO method developed in thelate 1970’s. The approach to pavement design hasadvanced considerably since that time. In orderto take advantage of these advances several state-of-the art pavement design methods wereevaluated against the TRIP method for use in theMunicipality.

The interim AASHTO method, upon which TRIPwas based, was developed from the results ofobservations of roadway performance on test bedsin the midwestern United States. This methodwas widely regarded as the best compromisebetween observation and analysis available in thelate 1970's. However, because of its originsprimarily in the Midwestern United States, theapplicability of the method to other climates wasquestioned. Further, the characterization of thesoil support was relatively unsophisticated, andthere was no way to directly treat the desired levelof confidence in the design. Economic analysisbased on life-cycle was not explicitlyincorporated. The method included no means forrepresenting the statistical validity of the soilsampling or the traffic design. AASHTOcontinued researching the performance ofpavements in the road test site to correct theseproblems after 1972. This research primarilyconsisted of more detailed monitoring of the testroad beds, to allow better correlations to bedrawn amongst more parameters than wereincluded in the original method.


Part 2 600-3

In 1986, a major modification was released whichprovided a significantly more sophisticated designand analysis tool. The improvements primarilywere in the areas of failure definition, statisticaltreatment, and soil characterization.

Performance and failure concerns wereincorporated in the 1986 edition by virtue of thenlonger term monitoring of the pavement sectionsin the original test. Pavement condition wasadded through the Pavement Serviceability Index(PSI), a qualitative evaluation of ride conditionusing a Likert-type scale. Using this approach, itis possible to select the amount of conditionchange which constitutes failure. A model wasdeveloped which linked the change in thepavement condition over time to the usage andenvironment of the roadway. In addition toproviding more performance-based design, thisimprovement also allowed life cycle cost analysis.

The underlying concept of life-cycle analysis is toselect a pavement solution for the transportationcorridor, rather than for the pavement itself.Simply put, the idea is to consider pavementsystems with a lower initial cost (perhaps due tothinner pavement) and a higher maintenance cost(including overlays) alongside methods withhigher initial costs and lower maintenance costs.Because of the serviceability index concept, onecan keep track of the changing pavementperformance with time, and thereby determine thetiming of major maintenance for economicanalyses. Most modern pavement design methodsutilize some form of life cycle analysis.

Also new in the 1986 interim AASHTO methodwas treatment of statistical variability. Thestatistical variability of the input parameters andpavement performance are incorporated throughtwo factors- reliability and standard deviation.The reliability factor accounts for chancevariation in traffic prediction and performance byallowing the selection of a degree of confidencethat the design will last the design period. Thehigher the desired degree of confidence in thedesign, the thicker the pavement. The standarddeviation factor accounts for statistical variabilityin the input parameters, particularly the trafficpredictions.

The last significant change was in the inputparameter to use for describing the supportingsoil strength. In the 1986 edition, the soil ischaracterized by the resilient modulus instead ofthe more nebulous soil support number used inthe 1972 interim method. The resilient modulusis a measure of the soil behavior after thousandsof load repetitions, and has come to be widelyregarded as the most accurate characterizationvariable for pavement design. Climate is directlyincluded in the resilient modulus determinationthrough the boundary values used for the test.

AASHTO released the final method in 1993. Themost significant changes in the intervening years(1986-1993) concerned the design method foroverlays and rehabilitation. A major evaluationof the performance of the design method and itsunderlying assumptions is currently underway inthe United States, as part of the StrategicHighway Research Program (SHRP). Thisanalysis includes detailed observation of nearly800 test sections scattered across all parts of theUnited States, and an assessment of the ability ofthe AASHTO method to predict serviceability andperformance. Preliminary results (SHRP, 1994)indicate that while traffic loadings are notoriouslyunder-predicted (a non-conservative error), theresults are to some extent offset by severe under-prediction of field moduli in the laboratoryresilient modulus test (a conservative error). Themajor change that is expected in the future will bedirect analysis of each potential failure mode,rather than the serviceability approach currentlyin use, which lumps together many differentfailure modes.

The AASHTO method has been modified bymany individual state departments oftransportation in the United States. The ArizonaDepartment of Transportation method (ADOT,1992) is optimized for the hot climate of thesouthwestern United States. The method is verysimilar to the AASHTO method, but deals moreexplicitly with the statistical variability of theunderlying soils. The resilient modulus is theoperative soil characterization variable, althoughdue to difficulty in measurement of the resilientmodulus ADOT uses a correlation with theHveem Resistance Value (R-value).


Part 2 600-4

Another method of potential interest is that usedby the Ministry of Communications of theKingdom of Saudi Arabia (MOC). This is arelatively simple method to apply, in which thesoil is characterized by the CBR, and the trafficby a 16-kip equivalent single axle loading.Design charts are then entered to perform theactual design. roads are placed into twocategories ("Expressways" and "Roads OtherThan Expressways"), allowing some treatment ofthe desired level of reliability.

Each of these methods incorporates all of thevariables described in the beginning of thissection, with the primary difference being thedegree to which these variables are explicitlyincorporated in the analytical portion of theanalysis. In general, one can characterize theAASHTO method as closest to the analytical endof the spectrum, and the MOC method as closestto the phenomenological end of the spectrum.There are methods which are even more heavilyweighted towards analysis, but these are mostcommonly used for research rather than practice.The methods described herein are consideredrepresentative of many methods in common usetoday, and are illustrative of the important factorsin pavement design.

604.01.02 Comparison of Design Results

Calculations were performed using the newestAASHTO method, the ADOT method, and theMOC method and compared with the TRIPmethod. In order to simplify direct comparison ofresults, the comparison was based on StructuralNumbers (SN) which result from each analysis,rather than on a comparison of the pavementsections themselves. This approach was usedbecause the SN is the most useful designdescriptor which results from the procedures, andbecause it is independent of the individualpavement layer components chosen by a givenagency.

High traffic, weak soil, or high degrees ofconservatism will all yield higher SN values, andthis number thereby allows direct comparison ofthe results of an analysis for similar inputvariables. For example, if two methods are usedthat generate vastly different SN values for the

same input variables, then one method can be saidto yield a substantially more conservative designthan the other. In the current case, we willcompare the SN value for the original TRIPmethod with the newer design methods using aconsistent set of material coefficients.

A SN was developed for each roadwayclassification pavement section described in theDCIL TRIP report. The TRIP SN are comparedto the SN resulting from each pavement designmethod used in this study in Table 600.02.

Table 600.02Comparison of Structural Numbers for

Multiple Design Methods

Design Truck Freeway Main SectorMethod Route Expressway Road RoadTRIP 8.40 7.28 5.69 3.31AASHTO 7.9-9.5 7.3-8.9 5.6-6.8 2.8-3.7ADOT 7.27 6.90 4.91 2.50MOC * * * 4.69

*Traffic values too far beyond the range of designcharts to allow extrapolation.

The AASHTO results show a range because ofthe correlation from CBR to resilient modulusrequired for the AASHTO method. A designCBR of 10 was used for the TRIP design. Inorder to correlate CBR to resilient modulus,AASHTO recommends the equation:

Mr = 1500(CBR) (Eqn. 1)

where-Mr = Resilient Modulus (psi)

CBR = California Bearing Ratio

Equation 1 was used to develop the lower SN'sshown in Table 600.02. However, there wasconsiderable scatter in the correlation between theCBR and the resilient modulus, with theconversion factor ranging to as low a value as750. In the absence of actual measured resilientmoduli with which to evaluate the applicability ofthe AASHTO conversion, a conservativeapproach was adopted in which the design wouldbe checked with a lower resilient modulus


Part 2 600-5

corresponding to the lower end of the AASHTOcorrelation range:

Mr = 750(CBR) (Eqn. 2)

The highest SN shown in each classification forthe AASHTO method results from a correlationto resilient modulus using Equation 2. This rangeshould capture the range of results likely to resultfrom actual resilient modulus testing. The ADOTmethod, which is also based on resilient modulus,was completed using the correlation recommendedby AASHTO and presented here as Equation 1.

The MOC method was only applicable for thelightest roadway classification, the Sector Road.In every other case, the design equivalent axleloading for the TRIP roadways was well beyondthe inference space depicted on the MOC designthickness charts. This result comes about due tothe degree of overloading common on TRIProadways, rather than to an excessive number ofvehicles. The MOC method is based on a 16-kipaxle load, requiring a large destructive effectfactor when considering that up to 27-kip loadswere used in the TRIP report.

As can be seen from Table 600.02, there is somevariation in the results based on the method used.It is readily apparent that the TRIP thicknessresults are well within the range of modernpavement design methods. The TRIP results arewell above the ADOT methods and firmly withinthe range of new AASHTO SN's. The method isnon-conservative compared to the MOC method;however, this comparison is believed to resultlargely from the large truck overloads leading tohuge traffic loadings compared to the 16-kipsingle axle loadings used for design in the MOC.

The conclusion is that the major modifications tothe AASHTO methods which have occurred sincethe original TRIP method was devised have notsignificantly altered the designs which would berecommended if the same input variables wereused to start the design process today. Thesuitability of the input variables, both standardand road specific, is therefore the mostappropriate question for the development of a newmethod. Of the methods examined, the 1993AASHTO method is the most appropriate choice.

The 1993 AASHTO pavement design method hasbeen used extensively in a variety of climatesacross the United States and many other parts ofthe world, and has been found to work effectivelyin a wide range of conditions. The pavementdesign method outlined below is based on the1993 AASHTO method with modificationstailored to local conditions.

The use of the AASHTO method will allow sitespecific treatment of individual roads within theMunicipality of special importance or roadsoutside the Municipality on less familiar or lessuniform soils. The following method should beused in conjunction with the 1993 AASHTOmethod for all Municipality pavement designs.

604.02 PAVEMENT DESIGN METHOD

Step 1: Develop Equivalent Single Axle Load,W18

Traffic is represented in the 1993 AASHTOmethod by the equivalent single axle load(ESAL), or the number of 18-kip equivalentsingle axle loads that will pass over the pavementduring its initial service lifetime (typically 20years). To calculate this value, three componentsare required:

(1) the number of vehicles which will pass overthe pavement during its lifetime, and

(2) the breakdown of those vehicles by weightclassification, and

(3) a means of converting the number of vehiclesin each class to an 18-kip equivalent singleaxle load.

To estimate the total number of vehicles utilizinga pavement during its design life, existing andprojected traffic volumes are needed. Todetermine the total number of vehicles, use astraight line interpolation between the existingtraffic volumes and traffic volumes of the designyear. For existing pavement studies, calculate theaverage rate between the existing traffic volumeand the traffic volume of the design year. Thataverage rate is then multiplied by the projecteddesign life of the pavement. For new pavementsthe number of vehicles would be estimated usingthe design period.


Part 2 600-6

The second component, the number of vehicles incertain weight classifications comes from detailedcounts of vehicle types in the traffic mix at avariety of times and places within each roadwayclass.

Finally, a means of converting the rough trafficnumbers, broken down by vehicle class, to the 18-kip equivalent single axle load is needed. Theaxle load equivalency factors used in the designmethod vary with the load on the axle, the type ofvehicle, and the pavement thickness. See theAASHTO guidelines for a complete set of tables.It should be noted that these tables do not reflectthe higher tire pressures that are often used in theMunicipality. However, the tabulated values stillform a good starting place for equivalencyfactors. For a simplified approach, the values inTable 600.03 form an acceptable interimapproach:

Table 600.03Generic Equivalency Factors

Vehicle Type Equivalency FactorHeavy Truck 6.5Medium Truck 1Light Truck .25Automobile .0008

Using these values and counts or estimations oftraffic loading within the classifications, theoverall 18-kip equivalent single axle loading canbe estimated. The advantages of the AASHTOequivalency factor approach outlined above arethat (a) the method can be used with very littledata about the traffic composition, or with verydetailed traffic counts; (b) most other methodsrequire very detailed information about tirepressures, wheel configurations, and load layouts,information which would be even harder to comeby than the traffic counts, and (c) the equivalencyfactors can be easily and directly incorporatedwithin the method. Ideally, detailed weight andcomposition data can be obtained to allow thedevelopment of system-specific equivalencyfactors, but the AASHTO factors can be used inthe meantime.

Step 2: Develop soil resilient modulus, MR

The resilient modulus of the soil subgrade isrequired for design and must be measured orestimated. The AASHTO correlation below givesreasonable agreement between the CaliforniaBearing Ratio (CBR) and the soil resilientmodulus. Unless site specific investigationsdetermine different resilient modulus-CBRcorrelation factors, the AASHTO correlationshould be used.

Mr = 1500(CBR)where:

Mr = Resilient Modulus (psi)CBR = California Bearing Ratio

Step 3: Determine the overall standarddeviation, So

The overall standard deviation is a dimensionlessparameter that accounts for random variation inthe traffic projections and normal variation in thepavement parameters. Simply put, it provides ameans of accounting for areas of weaker thanaverage pavement receiving higher than expectedtraffic. A value of 0.45 for So is commonly usedfor flexible pavement materials.

Step 4: Select the level of reliability, R

The level of reliability describes the degree ofcertainty that the pavement will last as long as thedesign service period. Statistically, the thicker thepavement section the higher the likelihood that thepavement will last throughout its intended servicelife, other factors being equal. The level ofreliability is represented in the AASHTO equationby the standard normal deviate, ZR, and in thedesign nomograph by R. Table 600.04 containsrecommended values for the roadwayclassifications. The table contains veryconservative values to reflect the need for highperforming pavements in a high-growth, lowmaintenance management mode.


Part 2 600-7

Table 600.04Reliability Parameters

Roadway Level of StandardClassification Reliability, R Normal

R Deviate, ZRTruck Route 99.9 -3.090Rural/Urban 99.9 -3.090Expressway 99.9 -3.090Main Road 99.0 -2.327Sector Road 95.0 -1.645

Step 5: Select design serviceability loss, ∆PSI

The pavement serviceability is a general measureof the pavements ability to service the trafficwhich must pass over it. Serviceability rangesfrom 0 (impassable) to 5 (ideal), and represents aquantification of subjective impressions about theroadway quality. Note that a low serviceabilityimplies only that the road has become difficult totravel over, and provides no information about thefailure mode (e.g. rutting, stripping, cracking)that has created the low serviceability. Thedesign serviceability loss (∆PSI) is the allowablechange from the initial serviceability (po) to theterminal serviceability at the end of the designperiod (pt). The design serviceability loss isobtained by simply subtracting the final valuefrom the initial value, and so describes theamount of degradation of service which isacceptable during the design lifetime.Recommended values for the different roadwayclassifications are shown in Table 600.05.

Table 600.05Serviceability Parameters

Roadway Initial Terminal DesignClassification po pt Serviceability

Loss, ∆∆PSITruck Route 4.2 3.0 1.2Freeway 4.2 3.0 1.2Expressway 4.2 3.0 1.2Main Road 4.1 2.6 1.5Sector Road 4.0 2.4 1.6

Step 6: Solve for the structural number, SN

The preceding steps 1-5 were independent.However, a value must be obtained for each onein order to complete step 6, solving for thestructural number. The structural number can besolved for using the equation below, using a trial-and-error procedure.

log10W18 = (ZR )(So) + 9.36log10(SN + 1) - 0.20

log10 ∆PSI 4.2-1.5

+ + 2.32log10MR - 8.07 1094 0.40 + (SN+1)5.19

Where:W18 = Equivalent Single Axle load, Step 1MR = Soil Resilient modulus, Step 2SO = Overall Standard Deviation , Step 3ZR = Standard Normal Deviate, Step 4∆PSI = Design Serviceability loss, Step 5

Or the solution may be obtained by using thenomograph in Figure 600.01 on page 600.10.

Step 7: Determine pavement and basethickness

Once determined from step 6, the structuralnumber is used to determine the thickness of eachpavement material layer using the appropriatematerial coefficients from Table 600.06.

Table 600.06Pavement Material Coefficients

Pavement CoefficientMaterial (per cm)

ai

Asphaltic Concrete 0.17Aggregate Base 0.05Sand-Asphalt Base 0.08Soil Subbase 0.04


Part 2 600-8

The structural number is related to thecoefficients as follows:

SN = a1t1+a2t2+a3t3+...+antn

where:ai = material coefficient for each material

in the pavement section (Table600.06).

ti = thickness of each material in thepavement section (cm).

SN = Structural number desired for thepavement section (Step 6).

Various combinations of pavement materials ofvarious thickness are possible to meet or exceed agiven structural number. Once the structuralrequirements are met the combination andthickness of the individual pavement materialsections is based on such factors as aggregateavailability , aggregate size, cost of variouspavement materials, minimum recommendedthickness, restrictions on overall thickness,number of lifts required. These factors arediscussed in more detail below.

Material Availability - Conservation of naturalresources should be given considered in theevaluation of the pavement design, and in areaswhere materials are scarce, availability should begiven considerable weight.

Continuity of Pavement Type - To maintainuniform driving conditions, consideration shouldbe given to continuing the same type of exitingpavements, especially if a new project is relativelyshort. This is assuming that the existingpavements are satisfactory.

Location and Local Conditions - Although thereare many pavement designs that will meet therequirements of the design equation, there aresituations when local conditions, such asunderground utilities close to the surface, poordrainage, flooding, etc. where one design mightfunction more efficiently than another. Pastexperience and judgement should be used in thefinal selection of the pavement design.

Anticipated Construction Problems -Consideration should also be given to thefeasibility of the proposed design in regard tostandard construction methods.

Costs - Comparative costs provided in thepavement design procedure should be givenconsideration in the selection of the pavementdesign. Consideration should also be given tomaintenance cost.

Minimum Structural Number - AASHTOdesign is based on traffic-induced fatigue failure.Establishing a minimum design takes into accountsuch factors as ease of construction, maintenance,current practice or failure under the action of afew heavy design loads. Table 600.07 should beused as a guide for minimum pavement design.

Table 600.07Minimum Pavement Design

Roadway Minimum MinimumClassification Structural AC

Number Thickness (cm)Truck Route 7.9 30Freeway 6.9 28Expressway 6.9 28Main Road 4.9 21Sector Road 2.5 11Low Volume 2.0 6

Additionally on layered sections using aggregatebase, a minimum thickness of 20 cm shall be usedfor the base material.

Normally, the pavement section which satisfiesthe structural requirements and represents theleast cost would be selected. However, aspreviously discussed, there may be times when theleast cost design would not necessarily be themost appropriate design. The following pagecontains an example of a typical flexiblepavement design.


Part 2 600-9

EXAMPLE FLEXIBLE PAVEMENT DESIGN

Given the bold faced information, determine the pavementmaterials and thickness required for a truck route.

Step 1 - Develop Equivalent Single Axle Load, W18Vehicles

perLifetime

Breakdownof Vehicles

Table 600.03Vehicle Equivalency Factors

W18

338502756 5% Heavy Truck 6.5 1100133965% Medium Truck 1 169251385% Light Truck 0.25 4231284

85% Automobile 0.0008 230182W18 = 131400000

Step 2 Develop soil resilient Modulus, MrMr = 1500CBR

= 1500(10) = 15000 psi

Step 3 Determine the overall standard deviation, SoSo = 0.45 Typical

Step 4 Select the level of reliability, RTruck Route, Table 600.04 R = 99.9 ZR = -3.090

Step 5 Select design serviceability loss, PSITable 600.05

po = 4.2pt = 3.0

PSI = 1.2

Step 6 Solve for structural number, SNSN =8.0

Step 7 - Determine Material ThicknessTable 600.06

PavementMaterial

Coefficient(per cm)

Trial Thickness(per cm)

SNContribution

Asphaltic Concrete 0.17 30 5.1Aggregate Base 0.05 22 1.1Sand-Asphalt Base 0.08 0 0.0Soil Subbase 0.04 45 1.8

Actual SN = 8.0

Note: Various material combinations can be compared economically to determine the optimum design. Make certain thickness meet Table 600.07.


Part 2 600-10

Figu

re 6

00.0

1


Part 2 700-1

SECTION 700DRAINAGE

701 GENERAL

Drainage is an important element of roadwaydesign. The objective of roadway drainage designis to provide the necessary facilities which allowthe public the appropriate use of the roadwayduring times of significant runoff and whichminimize the potential for adverse effects onadjacent property and existing drainage patterns.Toward this goal, roadway drainage design is tominimize off-project impacts while maintaininguse of the roadway at an acceptable frequency ofprotection.

There has been so much data and so manyguidelines written on the hydrologic and hydraulicaspects in roadway design that it is impractical tocontain all the references within this manual. Aseparate manual, “ROADWAY DESIGNMANUAL – Drainage,” has been prepared toprovide guidance and direction on the design ofthe drainage components of roadway facilities.Strict use of that manual does not replace soundengineering judgment. The drainage design mustbe undertaken by experienced drainage engineerswho are in responsible charge.


Part 2 800-1

SECTION 800UTILITIES

801 GENERAL

Utilities are an important element of roadwaydesign, especially in an urban environment.There are three categories of utilityimprovements:

Utility Protection- Existing utilities within theproject limits that have been determined to begeometrically compatible with the proposedimprovements; and are in good condition with anacceptable remaining service life; may remain inplace and must be protected from traffic loadsand maintenance operations. The traffic loadsconsist of both construction loading and post-construction vehicular loading.

Utility Relocation- Existing utilities that areincompatible with the roadway geometrics willrequire relocation, which may extend beyond thelimits of the proposed improvement depending onconnection requirements. Relocated utilities willbe replaced in-kind with the same size or capacityas the existing utility. The existing capacity maybe undersized and require an increase in capacityor other utility expansions or improvements maybe require. Such an up grade or developmentwork must be requested by the responsible utilityagency and approved by the Road Section beforethe design of the upgraded utility can be includedin the roadway project.

New Utilities- New service facilities that may berequired to support growth within the typical 20-year design life of the proposed roadwayimprovements; may replace redundant or outdatedfacilities or are major trunk lines routed throughthe project corridor that serve a broader purpose.

Utility planning begins in the preliminary designphase and is a factor in the project scopingprocess that leads to identification of the finalroadway geometrics. A thorough investigation ofexisting utility location and condition isundertaken as an early final design activity.

The Department’s objective is that Roadway andBridge projects are developed to include allrequired construction of utility protection,relocation and installation by the Contractor.This provides for single source responsibility forthe procurement of materials, and the schedulingof the proposed improvements; while minimizingdisruption of services to the public. This conceptreduces Contractor delay claims and the timerequired for advance utility works. The actualtiming and responsibility for construction ofindividual services will be determined on a projectby project basis.

Although contained in a single set of constructiondocuments, there are normally severalConsultants involved in the preparation ofindividual utility plans, specifications and BOQ.Several Municipality Departments use designatedConsultants for the planning and design of theirrespective services, as further described inSection 804.01. The Roadway/Bridge Consultantis responsible for overall coordination andpackaging of the documents into a complete andcomprehensive set of tender documents. Theparallel development of plans and specificationsby multiple Consultants must be continuouslymonitored to avoid conflict and contradiction.

802 UTILITY PLANNING

The Utilities Section of the Town PlanningDepartment is responsible for master planningand coordination of utility services. Servicecorridors will be reserved within each project forutilities in accordance with the planning dataobtained from the Utilities Section. The corridorsare established based on the approved designconcept and reflect the anticipated growth andoverall needs of the individual utility agencies.The agencies or Municipality departmentresponsible for the individual services are asfollows:

• Water - Water and Electricity Department(WED)

• Telephone and Telecommunications -ETISILAT

• Drainage - Abu Dhabi Municipality SanitaryDrainage Network Division


Part 2 800-2

• Electricity - Water and ElectricityDepartment (WED)

• Irrigation - Abu Dhabi MunicipalityAgriculture Section

• Sewer - Abu Dhabi Municipality SewerageProjects Committee.

• Gas Line - Abu Dhabi National OilCompany.

The Utilities Section will provide details on theagency or department responsible for specialservices such as oil and gas pipelines, 132 KVand national defense systems.

Information on existing utilities shall be obtainedfrom the Town Planning Utilities Section, theindividual Service (Utility) Departments and/orthe designated Consultant at the beginning ofdesign work. This data will include:

• Current Service Reservation Locations• Distribution of Services• As-built Drawings• Proposed Facility Plans

This information shall be compiled and analyzedto ascertain the status of each individual utility.Utility data should be supplemented by fieldinvestigation of the existing facilities includingsurveys to record structure locations and pipeinvert elevations. Manual(by hand) excavation tolocate services that are critical to the designshould be performed as necessary. TheConsultant will arrange coordination meetingswith the Service Departments to identify utilitiesto be protected, relocated to the servicereservations and new service requirements. Theservice authority may also have plans or projectsfor utility improvements in progress within theproject limits.

Once the scope of the utility works has beendefined, the Consultant will prepare separate costestimates of the utility works that are requireddue to conflict with proposed works and newfacilities that are proposed for inclusion in theproject by the utility agencies. It is important tomake a clear distinction between required worksand facility upgrades, since this information willbe used to determine the extent of the utilityworks to be included in the project and costsharing responsibilities. The Department will

review and give final approval of the projectutility scope of works. The utility planningprocess is depicted on Figure 800.01.

803 SERVICE RESERVATIONS

The Department’s objective is to locate all utilityservices in designated utility corridors or ServiceReservations. This policy applies to all projectsincluding new construction and roadwaywidening. Service reserves are located for ease ofconstruction and maintenance and to minimizedisruption or damage to permanent works causedby future utility installations or maintenanceoperations. The reserves are generally locatedoutside the roadway pavement in parking orpedestrian areas that are surfaced with removablematerials including interlocking tiles and precasttile blocks, and asphalt pavements of reducedthickness. Roadway crossings are perpendicularto the centerline and primarily concentrated atintersection locations. The design standardsrequire construction of ducts for all existing,proposed and future services that cross roadwaypavement. The utility corridors are defined inclose coordination with the project geometrics andthe Town Planning Department. The reserves areestablished within geometric criteria that is suitedto the installation of pipelines and conduits.Alignments are as straight as possible and anglepoints limited in severity with the degree ofdeflection ideally corresponding to pipelinefittings (22-1/2, 45 degrees).

The Standard Drawings show several differentdistributions of standard service reservations.Special reserves for any utilities other than thoseshown on the standard drawings (CCTV, 132KV, gas, oil.) shall be provided in each projectwith specific approval from the Town PlanningDepartment. Project design drawings should showa section view of these special service reservessimilar to that shown on standard drawings.Deviations from the standard distribution may bewarranted to:

• Accommodate existing utilities that would nototherwise require relocation.

• Suit the project geometrics.• Allow for constructability and/or maintenance

of service facilities with excessive width,diameter or depth.


Part 2 800-3

The final Service Reservation distribution andgeometry requires the approval of the TownPlanning Department.

804 UTILITY DESIGN

804.01 GENERAL

Utility design requirements will be defined onfinal determination of the scope of utility worksby the Department. The final design of eachutility will proceed based on the existing utilityinformation and proposed facility requirements.Refer to the Utilities Procedures Flow Chart,Figure 800.01.

In general, rapid development, incomplete as-builtinformation and the harsh soil conditions make itdifficult to determine the exact requirements foreach service line, especially minor branches andconnections, without the benefit of an extensivemanual excavation program to locate the utilities.As a result, this effort should be accomplishedduring the construction phase to enablepreparation of detailed shop drawings that willfully define the requirements for each utility. Theprocedure and specifications for this work areoulined in the Standard Specifications. Thetender documents are prepared based on the bestavailable information and may be limited to themajor components of a particular service. Thisprocedure varies with the different utilities andgenerally can be described under three categories:

Separate Plans and Specifications Prepared byAgency Designated Consultant- WED(Water)and Sanitary Drainage Network Section use adesignated Consultant for the design of facilities.Final design plans, specifications and BOQ areprepared as separate documents and included inthe project tender document package. Thedrawings will indicate the existing facilitiesanticipated to be protected, relocated orabandoned as well as new pipeline requirements.Based on the results of the manual excavation, theContractor will prepare detailed shop drawingsthat include refinements and adjustments to thetender drawings to reflect the conditionsencountered in the field. The shop drawingsrequire the approval of the designated Consultantand the WED.

Separate Plans and Specifications Prepared byUtility Authority- WED(Electric) andETISILAT normally prepare design plans andspecifications for their facilities in-house. WEDdevelops schematic drawings and estimatedquantities for relocation, protection, salvage andsupply of new cables for inclusion in the tenderdocuments. The drawings and Bill of Quantitiesare modified as necessary by the authority basedon the results of the manual excavation and issuedto Construction. The Contractor will thenprepare fully detailed shop drawings for finalapproval by the WED.

ETISILAT normally prepares detailed plans andspecifications for the work based on their recorddrawings of the existing telephone system and theneed for relocation or protection of plant impactedby the improvement project. These drawings arenormally included with the tender documents.Any necessary adjustments based on manualexcavation will be done through the shop drawingprocess in construction.

Consultant Prepared Plans and Specifications-The prime Consultant for the improvementproject is required to prepare final design plansand specifications for Surface Drainage, Lighting,Traffic Control and Drainage/Irrigation. Thedesigns are prepared in consultation with theagency or department and the drawings arenormally prepared as separate documents andincluded with the project tender documentpackage. Any necessary adjustments based onmanual excavation will be done through the shopdrawing process in construction.

804.02 UTILITY PROTECTION

All utilities under the roadway must be protected.This protection will continue under all pavementsand extend beyond the back of curb, edge ofshoulder or at the duct end wall constructed at theend of the duct by 0.50 meters. The StandardDrawings and General Specifications outline thetype of protection to be used for the variousutilities consisting of three types:

• Concrete Slab (Precast or Cast-in-Situ)• Concrete Encasement• Split Sleeve Concrete Encased


Part 2 800-4

These methods are designed to protect the utilityfrom induced traffic loading includingconstruction equipment loads. The Consultantshould check that the depth of existing utilities issufficiently below the subgrade level toaccommodate the protection device.

804.03 UTILITY RELOCATION

Utility relocation will generally be determined bythe individual utility agency and is subject toapproval by the Municipality. Each agency willsupply their relocation design drawings forinclusion in the Project documents. Thesedrawings will then be reviewed by theMunicipality to obtain their approval prior toinclusion in the Tender Documents. No utilitiesother than lighting, underground cables, andirrigation pipes shall be installed along the centralmedian parallel to the roadway. These lightingcables and irrigation lines in the median shall beas close as possible to the curb to avoiddisturbance to the greenery. Quantities, exceptfor relocation work designed by a designatedutility consultant, shall be calculated by theprimary Consultant. WED(E) and ETISILATwill supply respective relocation quantities.

Supply of all the materials required for therelocation works for electrical shall be included ineach contract. Removed and salvaged LV, 11KV and 33 KV cables excluding joints from sitecan be reused for the relocation works if approvedby the WED. Quantities for the supply andsalvage items shall be as estimated by the WEDfor each project. All 132 KV cables required forthe relocation work shall be new and shall besupplied under each contract.

804.04 CONTINGENCY DUCTS

Contingency ducts are required at roadwaycrossings for future services to be located inservice reserves and at other specific locationsestablished by the utility authority. Ducts areinstalled where pavements with asphalt or non-removable pavers cross over the service reserve.

These ducts may be designed to accommodateexisting or proposed service facilities with spareor reserve capacity for future (contingency)installations. Existing facilities such as cables or

conduits may be placed in split ducts and concreteencased.

Duct bank ends are terminated outside thepermanent pavement in a reinforced concrete endwall structure that allows access to the duct endswithout damaging the integrity of the structuralpavement section. These are required at allmultiple duct service reserve crossings. The endwall design and details are included in theStandard Drawings.

All duct crossing locations are to be marked in thefield with permanent markers as shown in theStandard Drawings. These markers are placed atthe end of the duct or set in the top of the duct endwall concrete.

804.05 UTILITY LOCATIONS

With the exception of lighting cable and irrigationdistribution lines, there shall be no construction ofutility lines such as power distribution lines,water lines, sewer lines, storm waterlines or anyother lines in the central median of primary roads.Utilities of all kinds shall not be constructedunder main roadway asphalt pavement. Utilitylines can be installed in service reserves undersector roads or parking areas where asphaltpavement is reduced in thickness.

804.06 NON-DISRUPTIVE ROADCROSSINGS

Utility crossings of completed permanent works,especially Main Roads, Expressways andFreeways are to be avoided. Contingency ductsor alternate routes should be used toaccommodate the service requirements wheneverpossible. When the crossing of primary roadwaysis unavoidable, Department policy requires thedesign to specify non-disruptive methods(pipejacking) or tunneling to cross the facility. Thisshould be a performance based specification tooffer the Contractor flexibility in selecting theequipment and methods.


Part 2 800-5

Figure 800.01Utility Procedures Flow Chart

New UtilityRequirements

Utility AgencyApproval

Town PlanningApproval

Utility AgencyAs-Built Drawings

Existing Utility Data

Determine Conflicts

Service Reserve Dwgs.

Town PlanningUtilities Section

Design Concept

Define Utility Scope of Work

Geometric Adjustment

Prepare Cost Estimates

Department Approval

Consultant DesignCoordination

Utility Design Agency Design

Designated ConsultantTender Documents

Record Drawings

Designated Consultant

Existing Utility Shop Drawings

Revised Design Drawings - RFC

Utility Works Shop Drawings

Resident Engineer Approval

Notice of Intent

Construction

Manual Excavation

Tender Drawings

Agency Review

As-Built Drawings

Town Planning Approval Agency Approval

Designated Consultant

Service Reservations

Consultant Review

CONSTRUCTION

PLANNING

DESIGN


Part 2 900-1

SECTION 900TRAFFIC ENGINEERING

901 TRAFFIC OPERATIONALANALYSIS

901.01 GENERAL

Part 1, Section 200, Design ConceptDevelopment, of this manual discusses trafficcounts and traffic projection methods suitable forthe design concept phase of a project. Part 2,Section 200, Geometric Design Standards,outlines the data required to develop a preliminaryparking demand analysis for inclusion in theDesign Concept Report.

Final design may require refinement of conceptdata before a final traffic report can becompleted. Specific model updating may benecessary to incorporate roadway networkchanges and revised roadway classifications.

Model output shall be calibrated to reflect currenttraffic trends by comparing the present actualtraffic volume to a current model run andapplying corrective adjustments to depict theactual conditions.

Model output shall be refined, particularly rampvolume and intersection turning volumes, tobalance the daily traffic volumes from networklink to network link. Directional design hourlyvolumes shall be derived in a manner similar tothe daily volume adjustments.

Sub-modeling computer programs should be usedto determine the roadway volumes associated withthe proposed frontage roads and other roadwaycharacteristics not incorporated in the originalmodel.

901.02 OPERATIONAL ANALYSIS

The final traffic report should include anoperational analyses utilizing the balanced trafficvolumes determined from the traffic forecasts.The analysis will follow procedures and methodsof the Highway Capacity Manual, By theTransportation Research Board and will include:

1. Ramp intersection capacity analysis.2. Ramp merge/diverge analysis.

3. Freeway weaving analysis.4. Basic segments capacity and operational

analysis.5. Intersection capacity and operational

analysis.

Signal warrant analysis shall be performed todetermine the need for signals at an intersection.The Manual on Uniform Traffic Control Devices(MUTCD) signal warrants shall be used for thispurpose. All necessary traffic engineering studiesrequired for signal warrants shall be conducted.

Where necessary, intersection simulation analysisshall be performed using a microscopicsimulation program that models individual vehicleflow. Optimal phasing/timing and coordinationparameters shall be used in the above mentionedoperational and capacity analyses.

For interchanges, conceptual designs will beassessed and recommendations provided formodification. Interchange operational analysesshall be performed to assess alternative conceptsonce the general plans of the alternatives havebeen developed.

Lane configurations and the required turn-lanestorage shall be designated at all intersections,furthermore, lane requirements of the freeway,mainline, ramps, cross-streets and frontage roads.The designations shall be a direct result of theanalyses performed and shall be incorporated intoroadway and bridge design drawings.

902 SIGNALIZATION

902.01 TRAFFIC SIGNAL DESIGN

Traffic signal phase and phase interval sequencediagrams shall be provided for intersections andinterchange ramp terminals. The signal systemdesign shall include the following:

• Signal pole locations• Mast arm orientation and lengths• Signal head locations on mast arms and poles• Signal face types• Conduits (ducts) location, including spares• Local Signal Controller and Changeover

Switch foundations locations


Part 2 900-2

• Red Violation Camera Loops and foundationslocations

• Closed Circuit Television (CCTV) Poles andCCTV Controller foundations locations

• Pedestrian signals locations and placement• Free Right Turn signal foundation locations• Pullboxes types and locations• Cabling requirements and terminations• Grades for system conduits (ducts) and

location of system detectors• Local intersection inductive detector loops

requirement, design and locations• Master Controller foundation requirement and

location

Phasing information should be used as a guide indetermining which phases and interval sequencesshall be provided at a specific location. Newsignals should be synchronized with the existingArterial Progression System and/or the CentralComputer Control System at the TrafficComputer Center.

All traffic signals and associated equipment shallbe in accordance with the StandardSpecifications. Any variance relating toequipment type or performance shall be approvedin writing by the Abu Dhabi Municipality.

902.02 SIGNALS, POLES, ANDCONTROLLERS

Only mast arm signal poles as per the standarddrawings shall be utilized. Combination mast armsignal and lighting poles or poles with multiplemast arms will not be used. All signal lenses shallbe 30 cm including arrow lenses. All signal headsshall be pole or mast-arm mounted. Span-wiremounted signals will not be used.

Pedestrian signals will normally be installed inpedestrian pylons. Where appropriate, pedestriansignals shall be installed on the traffic signal pole,on a street light pole, or on a separate 3.2 m pole.Pedestrian signals will have two signal sectionswith 30 cm lenses. The graphic symbols for‘WALK’ and ‘DON’T WALK’ shall be used.When illuminated, the DON’T WALK indication(hand palm) shall be red, and the WALKindication (man walking) shall be green.

A signal head shall be comprised of one signalface only. Typical signal locations shall be asfollows:

1. A minimum of one signal face shall beprovided for each separate vehicularmovement and a minimum of two signal facesshall be provided for each through or majormovement.

2. Vehicular signals shall be placed in such away so as to provide clear visibility toapproaching traffic. They shall be located noless than 12 m or no greater than 35 mbeyond the stopline.

Supplemental signal heads shall be used onlywhen warranted, and after a detailed study of thelocation is conducted.

There shall be one eight-phase, dual ring, singleentry, fully actuated microprocessor basedcontroller per intersection interconnected withexisting systems as required. The controller shallbe equivalent to a menu-driven NEMA typecontroller with LCD display capable of operatingin a closed loop coordination system.

Signal control details including signal plans andall traffic signal parameters for signal controlleroperation at an intersection/interchange shall beprovided. A note shall be included on the plansand specifications stating that the control cabinetis to be wired with the same phase numberdesignations as shown on the plans.

Traffic signal systems shall include inductive loopdetectors with adequate size, shape and number ofturns to provide proper actuation. Loop detectorsin bridge decks will normally utilize preformedloop detector material. Saw cutting of detectorloops in newly poured bridge decks will not bepermitted. Detector loops so located shall be castintegral with the bridge deck.

Separate loop wires for each loop shall beprovided. There shall be a splice to connect theloop wires to the lead-in cable in the curbsidepullbox. This lead-in cable shall be terminated atthe detector amplifier in the local intersectioncontroller. There shall be no splices in the lead-incable.


Part 2 900-3

Where feasible, power feeds for traffic signalsshould come from two separate substations andbe controlled by a changeover switch. This willenable signals to remain functional in the eventone of the substations loses power. Separate feedplans should be developed in cooperation with theWED.

The signalization design for each intersectionshall include as a minimum:

1. Plan symbols as shown on the standarddrawings.

2. A drawing of the overall layout depictingsignal pole, detector, signal head and conduitplacements. All vehicular and pedestriansignal indications shall be labeled bymovement (signal group) number.

3. A drawing including the pole schedule,detector schedule, clearance times matrix,phase movements, and if necessary, notesspecifically corresponding to the design andinstallation.

4. A drawing showing the conductor schedule.5. Additional drawings as necessary for

installation and materials details.

902.03 DUCTS AND PULLBOXES

All ducts shall be encased in concrete. Based onthe requirement, either 8-way, 4-way, 2-way or 1-way 10 cm diameter ducts shall be utilized.Raceways shall be 2-way 5 cm diameter exceptfor the traffic signal pole foundations racewayswhich shall be 3-way 5 cm diameter raceways.Standard pullboxes types (Type I, II and IV) shallbe used as appropriate.

902.04 PYLONS

Pylons are used to house the pedestrian signals.Their appearance and materials are meant to addcolor to the streetscape. They are comprised ofan aluminum tube column base and an aluminumcrown. External color is dark bronze.

Pylons with Type B crown are used at allsignalized intersections where pedestrian signalsare required unless pedestrian signals can bemounted on nearby light poles. Pylons with TypeB crown are placed within green areas at bothends and at the outer edge of pedestrian crossings.

If the width of the roadway median at theintersection is more than 5, but less than 10meters, an additional pylon is placed at themidpoint of the median with two pedestriansignals back to back. If the median width is morethan 10 meters, one pylon is placed at each edgeof the median, each with one pedestrian signal.

Each pedestrian signal is comprised of two signalunits with WALK and DON'T WALKindications. The DON'T WALK unit, mountedon top of the WALK unit, has a polycarbonatelens with black background and an illuminatedred “human hand” symbol placed vertically. TheWALK unit, mounted below the DON'T WALKunit, has a polycarbonate lens with blackbackground and an illuminated green “walkingman” symbol.

903 TRAFFIC SURVEILLANCE

Communication system facilities shall be installedon main roads, expressways and freeways. Thesystem will communicate traffic conditions to acentral computer, which will then communicateback with the ramp signals, changeable messagesigns and TV cameras. Interconnections betweensignalized intersections surveillance facilities andthe central computer will be through concreteencased, 4-way or 8-way 10 cm PVC ducts.

CCTV cameras are to be located at intervals ofapproximately one mile. Typical camera locationswill be at interchanges and at midpoint locationsbetween interchanges. To provide for futureimplementation, 2 stub-outs of 10 cm diameterschedule 40 PVC conduit, 1 m long, will beextended from a pull box nearest the midpointbetween interchanges. All conduit shall besecurely capped and locations precisely recordedon “as-built” plans. The locations, numbers ofducts and foundations will be determined from theCCTV Master Plan drawings.

904 SIGNING

General - Discussion in this section iscomplimentary to the MUTCD and shall be usedin conjunction with that document. However,policies presented in the MUTCD reflect generalpractices which may not always be applicable toAbu Dhabi. Where there are conflicts between


Part 2 900-4

this section, the Standard Drawings and theMUTCD, the guidelines in this section and theStandard Drawings should be followed, consistentwith sound engineering practices and judgement.

Traffic signs are installed to regulate, warn, andguide road users. Installation, reflectivity, legendsize, legend color, placement, and support typeshould all be considered to provide a consistent,safe and informative signing plan.

904.01 SIGN STRUCTUREINSTALLATIONS

904.01.01 Ground Mounted

Ground mounted signs are unobtrusive and canprovide drivers with the essential information inmost instances. They are appropriate for markingall intersections and most interchanges. Typicalguide sign treatments at expressway interchangeswith main roads are diagrammed in Figure 900.01and Figure 900.02.

Sign post lengths are to be calculated based uponthe Standard Drawings and the roadway crosssection at the sign locations. Foundations forstubs shall be flush with the ground and stubprotrusions of the concrete foundation shall alsoconform to the Standard Drawings. Signsinstalled in the median are to be designed for theultimate roadway section.

904.01.02 Overhead Mounted

Overhead signs may detract from the aestheticappearance of the roadway and architecturaltreatment of bridge structures. They also limit theclearances for large trucks and their loads. As arule, overhead signs should be used sparingly atlocations where ground mounted signs cannotprovide the essential directions to the motorist.

Overhead guide signs are principally applicablefor marking free flow traffic movements atinterchanges between rural expressways wherelane orientation is necessary for directing themotorist, or at locations where lateral space forground mounted signs is not available. Overheadguide sign use should be limited to:

1. Designating the lane use at forks of majorinter-city expressway routes.

2. Where roadway and ramp configurationsmay be misleading without lanedesignations, such as: locations where thethrough expressway lanes end beyond theinterchange in a terminal, or locationswhere two or more ramps depart from thethrough lanes and require lane usedemarcation for clarity.

3. Where lateral space is unavailable for aground mounted sign.

At interchanges between rural expressways, it isdesirable to sign the through expressway lanes inaddition to the ramp lanes. This can beaccomplished with a ground mounted guide signin the median, if the median is wide enough. If themedian width is inadequate, the through lanesguide sign may be cantilevered overhead in themedian. The ramp sign may also be cantilever-mounted for uniform appearance.

Similarly, space for other ground mounted guidesigns may be restricted, thereby indicating the useof an overhead cantilever mounting.

Typical overhead guide sign treatments at majorrural expressway junctions are portrayed inFigure 900.02.

Tubular Structure - Advanced guide and exitdirection signing on the mainline shall use tubularcantilever and tubular sign bridge structures.

The Standard Drawings have tubular signstructures which have been developed toaccommodate sign panels up to 4 m in heightincluding the exit panel. Therefore, all effortsshould be made to limit sign panel heights to 4meters. This may require some minor reductionsin legend size or spacing. The use of sign panelsin excess of 4 m in height will require a completesign structure design. Tubular sign structurestandards shall be incorporated in the final plansubmittal.

Interchange sequential signs shall be located inthe center of the median back to back on a singlestructure approximately halfway between


Part 2 900-5

interchanges. Existing structures shall be utilizedfor sign mounting wherever possible.

Bridge Mounted - Sign mounting brackets, forbridge mounted signs, are to be designed basedupon the criteria set forth in this manual for sizingsign panels. Cast-in-place anchor bolts shall beprovided with the bridge structure, together withall the necessary hardware for sign lighting.

904.02 SIGN SHEETING

Sign panel materials, reflectivity and color shallbe per the Standard Drawings and the StandardSpecifications. Any changes to the standards shallbe approved in writing.

904.03 SIGN TYPES

904.03.01 Regulatory And WarningSigns

Regulatory and warning signs inform drivers oftraffic regulations and warn of potentiallyhazardous conditions. Messages are portrayedusing standard international symbols. These signsare generally less than one square meter in area.

Post types and lengths shall be as per Figure900.03 and the Standard Drawings. Locationsshall be per the Standard Drawings and theMUTCD.

904.03.02 Guide Signs

Guide signs direct drivers to their destinations byinforming them of intersecting streets orprominent places along the route. Messages shallbe shown in both Arabic and English and vary inlength and height. Space for these messagesrequire large sign faces as well as structuralsupports. The guide signs may be groundmounted on the side of the roadway or mountedoverhead above the roadway or shoulder. Guidesigns shall be placed and designed per theStandard Drawings, the Standard Specificationsand the MUTCD.

Route markers shall be placed as separate signsand in conjunction with guide signs as shown inFigures 900.01 and 900.02. The background usedfor route markers shall be the falcon symbolshown below. The sign panel shall have a yellowlegend and border on a blue background.

Guide post types and lengths shall be as perFigure 900.04 and the Standard Drawings.

904.04 FINAL SIGNING PLANREQUIREMENTS

The final signing drawings should includeinformation and details not covered by theStandard Plans or Specifications such as:• Site specific sign details• Sign Layout Sheets with sign dimensions,

character dimensions, sign message, supporttype and reflective sheeting requirements.

• Plan sheets showing sign placement.Signing sheets may be combined with stripingsheets as long as the plans are legible. Scale shallbe such that all signs and markings are clearlydepicted.


Part 2 900-6

Figure 900.01Guide Sign Treatment

Interchanges With Main Roads


Part 2 900-7

Figure 900.02Guide Sign Treatment

Major Junctions Between Rural Expressways


Part 2 900-8

Figure 900.03Sign Installation And Post Selection


Part 2 900-9

AISC DESIGNATIONSDIMENSIONS IN CENTIMETERS

TWO POSTS

POST TYPE A = W6x15POST TYPE B = W10x22POST TYPE C = W14x26

SIGN DEPTH(cm)

SIGN WIDTH(cm)

POST TYPE

91,107 Up to 600 A122,137 Up to 500 A122,137 501 to 600 B

153,168 Up to 400 A153,168 401 to 600 B183,198 Up to 350 A

183,198 351 to 600 B213,229 Up to 250 A213,229 251 to 600 B

244,259 Up to 200 A244,259 201 to 500 B244,259 501 to 600 C

274,290 Up to 200 A274,290 201 to 400 B274,290 401 to 600 C

305,320 Up to 350 B305,320 351 to 600 C335,351 Up to 350 B

335,351 351 to 600 C366,381 Up to 300 B366,381 301 to 600 C

Note: For signs wider than 600 cm, use 3 posts.

Figure 900.04Sign Post Types


Part 2 900-10

904.05 ARABIC LETTERING FOR GUIDESIGNS

904.05.01 General

Guide signs shall be designed in Arabic andEnglish, with the Arabic message above theEnglish translation. To size the signs, the actualwidth of the Arabic and English messages mustbe determined.

904.05.02 The Arabic Alphabet

The first letter in the Arabic alphabet is “aleph”which is a simple downstroke. For the purposes ofthe Standard Script, aleph is used to proportionthe height of the letters. In developing theStandard Script, it has been determined that analeph height of 30 cm generally corresponds tosigning on freeways, while an aleph height of 24cm corresponds to signing on arterial roads.

Figure 900.05 provides spacing criteria for GuideSign design. Figures 900.06 through 900.17 aretemplate guides for Arabic letters and numerals.

When designing guide signs for all Abu Dhabiroadway projects, signs to be read from freewaysand expressways will have 30 cm (aleph height)Arabic lettering and 27 cm English lettering.Signs to be read from ramps and main roads willhave 24 cm (aleph height) Arabic lettering and 20cm English lettering.

904.05.03 Use of the Standard Arabic Script

The shape of each letter and number in theStandard Script is shown on a five-millimeter gridin Figures 900.06 through 900.17.

To get the actual width of a word on the guidesign, find the width of each letter shape in theStandard Script. Then multiply that width by theproportion of the aleph height in the final guidesign to the aleph height shown in the Script.Finally, add the width of each letter shape, takinginto account the spacing rules for unconnectedletters to obtain the total message width.

Arabic lettering is aligned on a baseline, just as inEnglish. The location of the baseline for eachletter is indicated by an arrow (V) adjacent to thatletter in the Standard Script. Some letters extend

quite a distance below this baseline; therefore, thevertical spacing on the sign face should bechecked and adjusted, if necessary.

The width of the message “Corniche Road” iscalculated in Example 900-01 on the followingpage. The page numbers refer to the fourteenpages in the Standard Arabic Script for HighwaySigns, Section 904.07. Aleph height was assumedto be 24 cm, slightly larger than the English 20cm lettering. Calculations proceed right to left.

Looking at the last letter in the first word, theshape extends 43 mm below the baseline. Usingthe proportion of 4.8, at least 20.64 cm will berequired between the Arabic and English messageto avoid conflict.

904.06 GUIDE SIGN DIMENSIONS

904.06.01 Single Message Guide Signs(Example 900-02)

After computing the preliminary sign width(message width, arrow width, and offsets) it shallbe rounded to the nearest 5 cm to get the finalsign width. Changes to the adjustable basedimensions most likely will have to be made toachieve this.

Sign faces shall be detailed as per the theoreticalheight dimensions for a particular sign. Smallvariations in the spacing between the legend andthe border can be used to increase or decrease theoverall sign height to an even 50mm increment.However, any reduction shall be limited to 90%of the original spacing.

Changes made to achieve the recommended heightand width shall be spread as evenly as possibleover the appropriate adjustable dimensions. If thepreliminary sign height or width is a halfwaybetween two recommended sign heights or widths,always round to the higher size.

Center the smaller lettering with the center of thewider lettering.


Part 2 900-11

Proportion: 24 cm = 4.8 5 cm

First letter: page 6; connected on left: 55 mm x 4.8 = 26.40 cmSecond letter: Page 3; connected on right 10 mm x 4.8 = 4.80 cmSpace: from Table A, 1-1/2 squares: 7.5 mm x 4.8 = 3.60 cmThird letter: page 5; unconnected: 30 mm x 4.8 = 14.40 cmSpace: from Table A, overlap by 1-1/2 squares: 7.5 mm x 4.8 = -3.60 cmFourth letter: page 9; end of word: 53 mm x 4.8 = 25.44 cmSpace between words: 6 squares: 30mm x 4.8 = 14.40 cmFirst letter: page 3; unconnected: 8 mm x 4.8 = 3.84 cmSpace: from Table A, 1-1/2 squares: 7.5 mm x 4.8 = 3.60 cmSecond letter: page 11; connected on left: 22 mm x 4.8 = 10.56 cmThird letter: page 10; connected both sides: 50mm x 4.8 = 24.00 cmFourth letter: page 12; connected on right: 45mm x 4.8 = 21.60 cmSpace: from Table A, no space: = 0.00 cmFifth letter: page 5, unconnected: 30mm x 4.8 = 14.40 cmSpace: from Table A, overlap by 2 squares: -10 mm x 4.8 = -4.80 cmsixth letter: page 11, connected on left: 22 mm x 4.8 = 10.56 cmSeventh letter: page 12, connected both sides: 27 mm x 4.8 = 12.96 cmEighth letter: page 6, end of word: 80 mm x 4.8 = 38.40 cm

Total Length of Message = 220.56 cm

Example 900-01Sample Calculation Of Arabic Message Width


Part 2 900-12

904.06.02 Multiple Message Guide Signs(Example 900-03)

For multiple message guide signs, the rules andbase dimensions for a single message guide shallapply, with a few additions and exceptions.

Guide sign width shall be determined by thewidest message (message width, arrow width andoffsets), measured as if it was a single messageguide sign.

To achieve a recommended height, changes in headjustable dimensions should be spread as evenlyas possible throughout all messages.

The multiple sign should be shown with a similardimensional breakdown as the single message sign(Example 900-02).

The following paragraphs provide guides for usewith messages containing arrows. Separate guidearrows for each message:

• The smaller message shall not be centeredwith the larger message, but placed with thesame offsets from the guide arrow side of thesign as if they were a single message sign.

• A single white stripe of 3 cm or 5 cm shall beplaced between all messages that use separateguide arrows. English and Arabic letteringshall be offset from this line as from theborder stripes in a single message guide sign.

• It is preferable to place the guide arrows onopposite sides of the guide sign.

Separate guide arrows for each message:

• These multiple messages shall be centeredwith the center of the largest message.

• The dimension between two messages shall bethe same as between the Arabic lettering andthe upper border stripe on a single messageguide sign.

• The guide arrow shall be vertically centered.It will also be horizontally offset from thelargest message as in a single message sign.

Separate guide arrows for each message (multiplemessages):

• The smaller messages shall not be centeredwith largest message, but placed with thesame offsets from the guide arrow side of thesign as if they were a single message sign.

• A single white stripe of 3 or 5 cm shall beplaced between all messages that use separateguide arrows. English and Arabic letteringshall be offset from this line as from theborder stripes in a single message guide sign.

• It is preferable to place the guide arrows onopposite sides of the guide sign.

Same guide arrow for multiple messages:

• These multiple messages shall be centeredwith the center of the largest message.

• The dimension between two messages shall bethe same as between the Arabic lettering andthe upper border stripe on a single messageguide sign.

• The guide arrow shall be vertically centered.It will also be horizontally offset from thelargest message as in a single message sign.


Part 2 900-13

Dimensions For Guide SignsAleph Height

24 cm 30 cm

A 3 5B* 20 27C 20 27D (See Note A)E 24 30F* 24 30G* 35 (See Note B) 40H* 30 (See Note B) 40J (See Note C)K (See Note D)

(A) 10 cm + largest distance an Arabic letter in the message goes below the baseline. (B) From the edge of the wider message, Arabic or English.

(C) See Standard Drawings for arrow dimensions.

(D) (Height of sign - arrow height) 2, use whole numbers.

* These dimensions may be adjusted to comply with recommended heights and widths.

Example 900-02Dimensions For Guide Signs


Part 2 900-14

Example 900-03Multiple Message Guide Signs


Part 2 900-15

904.07 STANDARD ARABIC SCRIPTFOR HIGHWAY SIGNS

This section consists of pages numbered 1through 14 of 14. The design of each letter andnumber is shown on a 5 mm grid in Figures900.06 through 900.17. Letter shapes are shownwhen the letter occurs at the end of a word (or isunconnected), at the beginning of a word, and inthe middle of a word (generally shown left to rightrespectively). The length of the connections toproceeding and following letters are included inthe design. However, they may be increasedslightly to maintain proper proportion with theEnglish legend if it is larger than the Arabiclegend.

Letter height and spacing between words shall bedetailed in the project drawings.

Certain Arabic letters are not connected withletters which follow in the same word. The spacebetween the letters and the letters which followthem are given in Figure 900.05.

1 of 14


Part 2 900-16

2 of 14

Figure 900.05Guide Sign Letter Spacing


Part 2 900-17

3 of 14

Figure 900.06Guide Sign Lettering


Part 2 900-18

4 of 14



Part 2 900-19

5 of 14



Part 2 900-20

6 of 14



Part 2 900-21

7 of 14



Part 2 900-22

8 of 14



Part 2 900-23

9 of 14



Part 2 900-24

10 of 14



Part 2 900-25

11 of 14



Part 2 900-26

12 of 14



Part 2 900-27

13 of 14



Part 2 900-28

14 of 14



Part 2 900-29

904.08 SIGN LIGHTING

Roadway sign lighting shall be as recommendedin AASHTO’s “An Informational Guide forRoadway Lighting”, 1984, pages 30-32.

Sign Lighting shall be designed using mediumambient illuminance in accordance with thefollowing table:

Table 900.01Sign Lighting

LightingLevels

Medium AmbientIlluminance

Illuminance 20-40 FcLuminance 48-96 cd/m2

The uniformity (maximum) for the illuminanceshall not exceed a ratio of 6:1, 4:1 is desirable.

904.09 SIGN LUMINARES

High-pressure sodium fixtures shall be used, 150watt size. Each sign lighting shall be designed formounting horizontally at the top of the signpanels, number and spacing of the fixtures shallbe determined during design. Maximum spacingof the fixtures should not exceed 6 m.

Sign lighting shall follow AASHTOrecommendations. Independent designcalculations are recommended using the designprogram Micro-Site-Lite, CALA or equivalent.The effect of adjacent roadway lighting on thesign should be considered in these calculations.

Each fixture shall be individually fused in aNEMA 32 box at each sign structure. If a signstructure has four or more sign lights, twoindependent circuits shall be provided for thatstructure.

905 PAVEMENT MARKINGS

905.01 GENERAL

Pavement markings shall be used for regulating,warning, and guiding road users. Discussion inthis section is complimentary to the Manual onUniform Traffic Control Devices (MUTCD) andshall be used in conjunction with that document.However, policies presenting in the MUTCD

reflect general practices which may not always beapplicable to Abu Dhabi. Where there areconflicts between this section, the StandardDrawings and the MUTCD, the guidelines in thissection and the Standard Drawings should befollowed, consistent with sound engineeringpractices and judgment.

All pavement markings and symbols shall bethermoplastic per the Standard Drawings and theStandard Specifications.

Typical urban layouts for pavement markings andraised pavement markers are shown in theStandard Plans. Raised pavement markers aregenerally not used in rural areas.

905.02 TYPES OF PAVEMENTMARKINGS

The following types of pavement markings shallbe used, as required:

1. Lane Markings2. Stop Line Markings3. Pedestrian Crossing Markings4. Channelization Markings5. Pavement Edge Markings6. Parking Space Markings7. Pavement Symbols (Arrows and Letters)

905.02.01 Lane Markings

In urban areas, markings separating traffic lanesin the same direction shall be comprised of typeCR and type NR pavement markers spaced asshown on the Standard Drawings. Markingsseparating exclusive turning lanes from throughtraffic lanes shall be type NR pavement markersspaced as shown on the Standard Drawings fromthe stop bar to the end of the taper.

In instances where two parallel and adjacentlongitudinal lines are placed, they shall be 10 cmapart.

For lane marking standards not shown in theStandard Drawings see Figure 900.18.


Part 2 900-30

Figure 900.18Lane Markings

905.02.02 Stop Line Markings

Stop line markings shall be continuous from curbto curb and shall be 30 cm wide as shown on thestandard drawings.

905.02.03 Pedestrian Crossing Markings

Pedestrian crossings shall be marked bylongitudinal stripes through the width of thepedestrian crossing which shall be 4.0 m. Stripesshall be 50 cm wide, with a 50 cm gap betweenadjacent stripes.

The distance between the upstream edge of thepedestrian crossing and the beginning of theadjacent stop line shall be 1.0 m.

905.02.04 Channelization Markings

All channelization markings, except thosementioned above, shall be 20 cm wide solid lines.Dead areas created by channelization will havechevrons which shall be comprised of 20 cmcontinuous line.

905.02.05 Pavement Edge Markings

Pavement edges shall be marked only when thereis no curb. The marking shall be a 10 cm widecontinuous white line on the outside edge and ayellow line on the inside edge with correspondingtype CR or YR pavement markings at 16.0 mintervals as shown on the Standard Drawings.

905.02.06 Parking Space Markings

Parking space markings shall be used whereverparking is allowed. They shall be 10 cm widesolid lines showing the borders of each parkingspace.

905.02.07 Pavement Symbols(Arrows and Letters)

Arrows shall be used, as necessary, to indicate thetypes of movements, that can be made from thelanes where arrows are placed. They shall besolid, elongated, and 5.0 m long. The shape shallbe as specified by international standards.

Letters, whenever used, shall be solid, elongated,and 3.0 m long. The shape shall be as specifiedby international standards. Letter messages shallbe both in Arabic and English.

906 MAINTENANCE OF TRAFFIC

During Construction, existing traffic flow will bemaintained on paved, lighted detour roads. Ingeneral, detours will have two through lanes ineach direction.

906.01 CONSTRUCTION STAGING

Construction will be staged so as to avoiddisruption of traffic flow as much as possible.When required and possible, pedestrianmovements will be maintained by temporarysidewalks.

Temporary pavement shall be used for alldetours. Temporary lighting shall be providedduring all stages of construction, includingtemporary detours.


Part 2 900-31

906.02 SAFETY MEASURES

Standard barriers, barricades, signs, flashers andother protective measures will be provided forguiding, warning, and protecting vehicular andpedestrian traffic during construction.

All road closures and construction traffic shall becoordinated with local police and fire services.

906.03 TEMPORARY TRAFFIC SIGNALS

At locations of complex traffic movements,temporary and portable traffic signals will beused for the safe, orderly movement of trafficduring construction.

906.04 MAINTENANCE OF TRAFFICPLANS

A work phase plan shall be established byconstruction phases or sequence, indicating theduration of each phase or sequence. The planshall include but not be limited to:• maintenance of traffic circulation during

construction,• traffic control methods that need to be

implemented,• construction detours,• Work areas per stage,• temporary barrier locations and details,• temporary signing and striping locations and

details,• temporary construction quantities.


Part 2 1000-1

SECTION 1000LIGHTING

1001 ROADWAY LIGHTING

1001.01 GENERAL

The main function of roadway lighting is toimprove driver visibility. A well illuminatedroadway increases safety by allowing drivers toidentify potential hazards or conflicts. Welldesigned lighting allows the driver to quicklyrecognize roadway features such as alignment,delineation, intersections, ramps, traffic signs,traffic signals, and pedestrian crossings. Theimproved driving environment in turn improvestraffic operations, capacity and safety.

Lighting continuity is recommended for estheticand functional reasons. Lighting continuity helpsdrivers identify roadway facilities and acts as aunifying design element.

Lighting design responsibility generallyencompasses entire roadways within the projectlimits. However, at the time of concept planning,the design responsibility may be reduced orexpanded by the Municipality. The designershould consult the Road Section as to anyvariation in the design requirements.

1001.02 LIGHTING DESIGNCONSIDERATIONS

Freeways and ExpresswaysBecause freeways and expressways are wide andhave higher traffic speeds, general street lightingrequirements are inadequate for freeway andexpressway lighting. High lumen lamps inconjunction with high mast poles are used toilluminate large roadway areas and reduce glare.

InterchangesHigh mast lighting is ideal for illuminatinginterchanges and other large areas, because theillumination pattern is not confined to the basicdriving lanes. High mast lights illuminate theentire interchange, creating the same overall viewof the area as that perceived in daylight. Highmast poles can be installed in suitably widemedians on multiple-lane roadways. This type of

lighting enhances traffic safety through highvisibility, the need for fewer poles, and greaterflexibility in their location.

Arterials and Frontage RoadsArterials serve moderately high volumes of trafficat lower speeds than freeways and expressways.Although their primary function is to move andmaintain uninterrupted traffic flow, theyfrequently have busy at-grade intersectionsrequiring traffic control devices. These at-gradeintersections require greater visibility for trafficsignals, signs and the resulting crossing andturning conflicts.

Also, increased commercial development alongarterials means increased pedestrian movementsand possibly the need to accommodate publictransportation (taxicabs and buses). Adequatelighting for pedestrian movements and publictransportation’s frequent stopping, loading andunloading of passengers is vital to safety alongarterials. Arterial lighting must also blend withcommercial development lighting to avoidcombinations which detract from the overalllighting or result in poor visibility.

Sector RoadsA sector roads primary function is to providedirect access to adjacent properties. Althoughtraffic speed is low, traffic volume can be heavyand frequently interrupted especially in residentialand commercially developed areas. Because ofincreased access to commercial and privateproperty, sector roads, compared to arterials,must accommodate an even heavier volume ofpedestrian movement. Lighting considerations aremuch the same as for arterials.

Intersections and Pedestrian CrossingsLighting intersection and pedestrian crossings isof particular concern and must be adequate fortraffic and pedestrian security, as well as meetingenvironmental objectives. If necessary for trafficsafety, pedestrian security, or to enhanceappearance, the lighting color should be varied todefine the various elements more clearly.Generally, the illumination level at an intersectionof two at-grade roadways is the sum of theillumination of the two roadways.


Part 2 1000-2

Table 1000.01Illumination Requirements

Roadway MinimumIllumination

(Lux)

UniformityRatio

LightSource

Lantern PoleHeight

(m)Freeways &Expressways

22 2:1 HPS Cut-off Type III 30.5

Interchanges 22 2:1 HPS Cut-off Type V 30.5 ***

Main Roads/Arterials

22 2:1 HPS orMH

Rectilinear, Sharp Cut-off 14

Sector Roads/Ramps

15* 3:1 HPS orMH

Rectilinear, Sharp Cut-off 10 ***

Crosswalks 33 2:1 HPS orMH

Rectilinear, Sharp Cut-off 10-14

Ramp Terminals&Traffic ConflictAreas

40** 2:1 MatchRoad

Cut-off Type 30.5 *** or 14

Parking Areas 15 3:1 HPS, orMH

Rectilinear, Sharp Cut-off 10

Sidewalks AwayFrom Road

10* 3:1 HPS Decorative 4.6

HPS - High Pressure SodiumMH - Metal Halide

Notes:1. Lamps for sign lighting should be a different color from roadway. Mercury vapor lamps for sign

lights will provide good contrast and easy differentiation from high pressure sodium roadwaylighting.

2. Recommended illumination level indictates the minimum allowable. Individual designs shall specifylighting levels as advised by the Municipality/WED at the design phase.

* On high volume roads, lighting will be upgraded to suit conditions.** Areas of traffic conflict would have high levels of illumination equal to the sum of values

recommended for each of the intersecting roads.*** Use high mast with HPS on ramps wherever possible.

Rural LightingRural roadway lighting is generally warrantedonly at decision points such as interchanges orintersections. However, accident records shouldbe examined to determine if poor visibility was arecurring factor. Continuous lighting on ruralroadways may be considered early in the designprocess.

1001.03 ILLUMINATIONREQUIREMENTS

Table 1000.01 summarizes the illuminationrequirements for various roadways.

IlluminationIllumination levels stated in Table 1000.01represent the lowest average maintained levelsconsidered appropriate for each kind of roadwayor walkway in the various areas. Illumination


Part 2 1000-3

criteria and calculations are based on theIlluminating Engineering Society’s (I.E.S.)standards modified to meet the higher uniformityand illumination levels required by the WED andthe Municipality of Abu Dhabi.

Uniformity RatioA Uniformity Ratio (UR) is defined as theaverage maintained illumination of the roadwaydesign area, divided by the lowest value at anypoint in the area. See Table 1000.01 for roadwaycriteria.

Light SourceLight sources shall be as identified in Table1000.01 and as modified during the design phaseif advised by the Municipality. It is importantthat the lighting design be compatible with thesurrounding area.

The roadways not identified in this manual willuse a light source as directed by the Municipality.Side roads and ramps shall have the same lightsource as the adjacent main roads. Metal halideor high pressure sodium shall be selected to blendwith the surroundings on sector roads.

Lantern and Lamp Selection“Sharp cutoff” lanterns are proposed for roadwaylighting per Table 1000.01. These lanterns aredesigned to illuminate a relatively large areawithout spilling light into adjacent areas. Theyproduce uniform illumination and minimum glare.

High pressure sodium lamps provide excellentgolden white color and enhance the estheticqualities of concrete, stone and brick. Metalhalide gives a whiter light, providing a colorcontrast to sodium lamps, and enhance theappearance of green and pastel colored materials.

The lanterns shall be mechanically strong andeasy to maintain. They shall be of adequatedesign to operate at mounting heights of 30.5meters and able to withstand sustained windspeeds of 160 kph with 208 kph gusts.

Lanterns mounted on 14 meter poles shall be1000 Watt high pressure sodium, metal halideand mercury vapor lanterns cut-off, and provideefficient even illumination.

Lanterns mounted on 10 m poles shall be 400watt high pressure sodium or metal halidelanterns.

Lanterns shall have optical systems sealed againstmoisture, dirt and insects, and be mechanicallystrong and easy to maintain.

Glare control for the mounting height specified,and cut-off characteristics shall be designed basedon I.E.S. standards.

Lantern Mounting HeightHigh mast lighting (30.5 m) is proposed forapplicable interchanges and between closelyspaced interchanges when conditions permit. Onmajor thoroughfares not suitable for high mastlighting, but where substantial lightingrequirements remain, pole heights would be 14m.

High-mast lighting (30.5 m poles) shall be usedon rural and urban freeways and expresswayswith wide medians where one row of 14 m polesis not suitable. The 30.5 m poles shall also beused at all interchanges. Wherever possible highmast lighting shall be used for ramps.

High mast lighting will be used on main roadsonly when light height will not substantiallyinterfere with nearby buildings. On other majorthoroughfares, poles would be 14 m high andwould be placed at the side or in the median of theroadway, as applicable. Single or multiplelanterns would be used to provide uniformillumination of the roadway.

1002 PARKING AREA LIGHTING

1002.01 GENERAL

The function of light sources in parking areas isto give an overall view of the parking area andprovide a measure of security. Lighting is alsocritical for vehicle maneuvers such as backing.


Light source shall be high pressure sodium ormetal halide selected to blend with thesurroundings per Table 1000.01.


Part 2 1000-4

1002.03 LANTERN MOUNTING HEIGHT

Ten meter high poles shall be used for all parkinglot areas. Lantern configuration and lightdistribution shall be selected to suit the parkingarea geometry.

1002.04 LANTERN SELECTION

Lanterns shall be as detailed in the GeneralSpecifications and Table 1000.01.

1003 SIDEWALK LIGHTING

1003.01 GENERAL

Sidewalk lighting provides visually pleasant anddecorative illumination to sidewalks adjacent tobuildings, to buildings themselves and to the otherpedestrian walkways.


Light source will be high pressure sodium perTable 1000.01 unless otherwise directed by theMunicipality. Sidewalk lights will be providedonly for the areas specifically advised by theMunicipality.

1003.03 LANTERN MOUNTING HEIGHT

Sidewalk light poles shall generally be 4.6 metershigh with 2-100 watt high pressure sodiumlanterns. However, special pole heights andlantern types may be required to meet specialsituations. The Project Design Manager shouldconsult the Municipality as to the exact nature ofthe requirements at the time of concept planning.

1003.04 LANTERN SELECTION

Ornamental lighting of proper height for thepedestrian is proposed for sidewalks alongbuildings and in parks and landscaped areas.Low-level ground lights would be used toilluminate vegetation.

1004 LIGHTING CONTROLS

1004.01 GENERAL

These items provide required electricalconnections and controls to all roadway lighting,decorative lighting and street furniture lightingitems (i.e. bus shelters, telephone booths andsidewalk lights).

1004.02 LIGHTING CONTROLLERREQUIREMENTS

Lighting shall be controlled by a 24 hour timingswitch. Control cabinet requirements shall be asspecified in the Standard Specifications.

1004.03 DESIGN STANDARDS ANDPROCEDURES

Control cabinets should be located in the medianwhere feasible. The maximum voltage drop in theoutgoing circuits beginning at the control cabinetshall be four percent. Branching of undergroundcable circuits from all lighting units except 4.6 mpoles will be allowed. There shall not be anyintermediate joints in the lighting cable circuitryexcept the terminations in the lighting units or inthe junction boxes.

1005 POWER DISTRIBUTION

Electric service is 415/240 volts, three-phase,four-wire, 50 Hz system furnished by the Waterand Electricity Department (WED). This serviceshall be provided at the lighting control cabinets.Underground distribution to the lighting unitsutilizes four conductor and steel wire armoredXPLE insulated cables. Conductor size will be25 mm2 for all 30.5 and 14 m light poles and 16mm2 for all 10 and 4.6 m poles, street furnitureand decorative lighting units. The lanterns will beconnected in phase sequence to provide abalanced three-phase load.


Part 2 1000-5

Type IV pull boxes shall be used adjacent to lightpole foundations in paved areas except whereinterlocking pavers are used. They should beinstalled between the foundation race way conduitand the electrical conduit. Cables shall be directburied under sidewalks and interlocking paversused in parking areas except at the entry or exit ofsector roads or parking areas where PVC ductsshall be provided. Cables under interlocking tilesat the entry or exit of sector roads and parkingareas, shall be through concrete encased PVCducts.

All PVC conduits and ducts for undergroundcable lighting circuitry, shall be a minimum of 10cm diameter. There should be a minimum of onespare duct at each crossing. Where lightingcables are proposed along the service reserves atroad crossings, the available electrical ducts shallbe used. Separate lighting road crossing ducts arenot required at these locations.

The underground lighting cables shall be installedalong electrical service reserves in all possiblecases. Wherever the lighting cables are proposedoutside the service reserve, the cable route shallbe immediately adjacent to the curb line.

Separate earthing is required only at the terminalpole of each circuitry. All light poles and fixturesshall be earthed through the cable armoring.

1006 DESIGN AND SUPERVISIONRESPONSIBILITIES

The Municipality is responsible for the lightingcriteria standards to light the roads. Thiscriterion covers illumination levels, uniformityratios and distribution and differences inbrightness of the roadways. WED may suggest/advise of criteria orimprovements in lighting for the Municipality andits Consultant to consider in design andconstruction. However, WED responsibility islimited to advising of its requirements formaintenance and access to the lighting poles andlanterns for inclusion in the Specifications. TheMunicipality and its Consultant are responsiblefor adherence to the lighting specifications. WED is responsible for the technicalspecifications and sizing for the electrical powersupply for the lighting system includingunderground cable circuits, fuses, controlcabinets, pull boxes and conduit. Accordingly,WED will be responsible for review of contractorsubmittals covering these items during theconstruction period. WED shall have the right toinspect such construction in the field and approvalby WED shall be required prior to burial of theunderground cable circuitry by the Contractor.


Part 2 1100-1

SECTION 1100ROADSIDE DEVELOPMENT

1101 LANDSCAPING

Landscaping and the associated irrigation systemfor the roadside areas and medians will bedesigned by the Agricultural Section of the AbuDhabi Municipality. The Design ProjectManager is responsible for coordinating with theAgricultural Section to ensure that they are awareof the Project and its design schedule.

Special permission from the Municipality isrequired for the removal of any green (planted)area. Newly created areas suitable for plantingalong with remaining green areas must beidentified and presented on the General Plans.The Design Project Manager must provide theseplans to the Agricultural Section so that they candesign the new landscaping and irrigation system.Close coordination with the Agricultural Sectionis essential to ensure that the irrigation design iscompleted early enough to be incorporated intothe Tender Documents of the roadway project.

Agricultural planting areas should be shown onthe general plans designated as green areas.Green areas within the residential sectors, (sectorspredominantly villas or low rise structures),should be maximized while reducing paved areas.In general the green areas should be limited to thefront portion of building plots. The areasbetween and behind the existing buildings shouldbe paved with pedestrian or vehicular pavers asapplicable. However, each sector must beconsidered individually. Local residents,Mosques, Embassies and/or some othersignificant feature within the sector, often requirespecial (non-standard) treatment.

1102 IRRIGATION

It may be required to design an irrigationreservoir with electrical and water services. Ingeneral, it will include the reservoir, pump-housestructure and the incoming services, but will notinclude the interior piping, wiring or pumpingsystems.

The Agricultural Section will determine if areservoir is required on a project. They will, alsodetermine its location and size. However, finalapproval for including this work in a project mustcome from the Road Section.

1102.01 IRRIGATION DUCTS

All irrigation facility crossings of all roadwaysshall be accommodated within a duct. Ductdetails are included on the Miscellaneous UtilityDetail Standard Drawings. Duct crossings shouldbe located within allocated service reservationcorridors.

Guidelines for providing the irrigation ducts andappurtenances are:

1. Ducts for irrigation lines may be GlassReinforced Plastic (GRP) orPolyvinylchloride (PVC) pipe conforming tothe Standard Specifications.

2. Generally, ducts will be provided under the

roadway at intersection crossings. Additionalcontingency ducts shall be located at spacingof approximately 250 to 300 meters betweeninterchanges. Specific contingency ductrequirements for each project must becoordinated with the Agriculture Department.Ducts under the roadway pavement must bealigned with each other in the median, bothhorizontally and vertically.

3. Ducts should normally have one meter of

cover, however, one-half meter of cover isacceptable where positioning is due toconflicts with existing or proposed utilities.In superelevated sections, the ducts shouldhave approximately the same degree of crossslope as the highway. All ducts should havea nominal (1%±) slope for drainage.

4. The end of ducts must extend 0.5 meters

(minimum) past back face of curbs orsidewalks when in curbed situations.

5. The end of the ducts should extend into the

verge area in an un-curbed condition. Theintent is to maintain the cover from the


Part 2 1100-2

sideslope at one meter (minimum) where theirrigation line comes out of sleeve.

6. Ducts should be considered where

maintenance roads and driveways crossirrigation lines.

1103 FENCING

The Designer and Abu Dhabi Road Section shallreview fence requirements on a project specificbasis.

1104 SLOPE PAVING

Slope paving at bridge abutments shall conformto the Abu Dhabi Road Section Standard slopepaving details.

Where the mainline is depressed below the localcrossroad, the slope paving shall approximate thetypical cross section contours. A 6 meter gradingtransition at each edge of the slope paving shouldbe indicated on the plans.

Special treatment of slope paving may beapplicable at specific locations. The Designershould coordinate slope paving treatments withthe Abu Dhabi Road Section.

1105 SWEET SAND COVERING

In general, all proposed green areas shall becovered with a 30 cm minimum depth of sweetsand at the finish grade.

The Designer shall calculate the quantity of sweetsand required for the project. The General Plandrawings will show the green areas included in theproject.

1106 STREET FURNITURE

1106.01 GENERAL

Street furniture to be provided as part of the AbuDhabi Roadway Section projects includesbenches, bus shelters, telephone booths andsidewalk lighting. The purpose is to providepedestrian amenities and to enhance the urbanenvironment with street furniture that has a

uniform and visually pleasing design andappearance.

In general, street furniture will only be providedin roadway projects at the direction of the RoadSection. For urban interchange projects,installation of street furniture will be included aspart of the proposed improvements. On ruralinterchange contracts, the extent of streetfurniture required could range from pedestriansignals to a full compliment of street furnitureelements. On all types of projects, during theclose of the Concept Phase, the Designer shouldconsult with the Abu Dhabi Road Section todetermine the types of street furniture that shouldbe provided.

Descriptions of the basic function, elements,design standards and procedure for each streetfurniture item are included in following sections.

1106.02 DESIGN

Details of street furniture have been designed andshown on the Standard Street Furniture Detaildrawings and in the Standard Specifications.These details do not have to be revised from onecontract to the other unless there is a project-specific requirement.

1106.03 BENCHES

Benches provide resting facilities for pedestrians,much needed in Abu Dhabi in view of the warmclimate. There are three types of benchesdesigned for the Abu Dhabi Roadway Sectionprojects, Type A, Type B and Type C.

1106.03.01 Type A bench

This type of bench is comprised of two precastconcrete ends and wood slats (over aluminumtubes), and does not have a backrest. The Type Abench is always used in combination with theType B bench, except when it is used at taxistops.

1106.03.02 Type B bench

This type of bench includes a back rest, a planterand a waste receptacle. Basic elements of thebench itself are the same as the Type A bench,


Part 2 1100-3

except for the back rest and higher ends. TheType B bench is also used in combination with aType A bench to create a small gathering placefor a group of people.

1106.03.03 Type C bench

This type of bench is comprised of the sameelements as a Type A bench except it is used onlyin bus shelters.

Subject to space availability, basic criteria forplacement of benches are as follows:

1. Two combination Type A/Type B benchesare placed at every intersection, with each indifferent quadrant (preferably diagonalquadrants).

2. If space does not permit the abovearrangement, a Type B bench is placed in thesame fashion.

3. At least two Type B benches are placed ateach side of the main road between twointersections.

4. Two Type C benches are placed within eachbus shelter (considered as part of and paidunder bus shelters).

5. One Type A bench is placed at each taxi stop.

1106.04 BUS SHELTERS

Bus shelters are placed on bus stop sidewalks toprovide shade and seating for bus passengers.

Bus shelters are to be placed at every bus stopexcept where space limitations prohibit their use.They are to be located at the far (downstream,according to the direction of traffic) end of thebus stop with one meter from the edge of thecurb.

1106.05 TELEPHONE BOOTHS

Foundations for telephone booths will be providedin road projects, the telephone booth andoperating equipment are the responsibility ofEtisalat.

Etisalat determines locations and quantity oftelephone booths to be included in each Contractas approved by the Road Section.

1107 NOISE ABATEMENT

The Designer and the Abu Dhabi Road Sectionshall review any noise abatement requirements ona project specific basis. In general, the Designeris to mitigate, as much as possible, any increasein the traffic noise, especially in residentialneighborhoods.

In special circumstances involving sensitive areas,depressed roadways or noise abatement walls maybe required.


Part 3 100-1

PART 3STRUCTURE DESIGN

SECTION 100DESIGN CRITERIA

101 GENERAL

101.01 PURPOSE

The purpose of this section is to provide BridgeDesign Criteria in order to establish a uniformproject design and construction policy that willaid the Consultant in the preparation of finaldesign, plans and specifications, and insure safeand uniform structural capacity throughout theproject.

Structures shall be designed in accordance withthe latest edition, including revisions, of theStandard Specifications for Highway Bridges -published by the American Association of StateHighway and Transportation Officials(AASHTO) and the Structural Design Standardsincluded herewith in Part 3 of this RoadwayDesign Manual. The design shall be based on thelatest edition of the AASHTO specifications asexisting on the date of the design contract. TheStructural Design Standards presented hereundershall govern over the AASHTO Specificationswherever the are “At Variance With” or “InAddition To” the AASHTO Specifications.

These criteria set forth minimum standards. TheConsultant may propose more conservativecriteria if, in his judgment, such criteria arerequired. However, all deviations from thecriteria must be justified and receive priorapproval from the Abu Dhabi Roads SectionProject Manager.

101.02 DEFINITIONS

The following definitions and abbreviations areprovided to clarify usage of terms and to avoidthe need for excessive verbiage.

AASHTO—American Association of StateHighway and Transportation Officials StandardSpecifications for Highway Bridges, 15th Edition-1992, including all Interim Specifications todate.

Approval—Approval as obtained from the AbuDhabi Roads Section Project Manager.

Drainage Report—The Drainage Report asproduced by the Bridge Drainage Section or,when applicable, by a consultant.

Geotechnical Report—The Geotechnical Reportincluding the Foundation Design Report asproduced by the Geotechnical Section or by aconsultant.

Special Provisions—The Special Provisions tothe Standard Project Specifications as specificallywritten for each individual project.

Standard Specifications—The Standard ProjectSpecifications

AASHTO Specifications for StructuralSupports—The AASHTO StandardSpecifications for Structural Supports forHighway Signs, Luminaries and Traffic Signals,latest Edition.

101.03 BRIDGE TYPES

Bridge Definition—“A ‘Bridge’ is defined as astructure including supports erected over adepression or an obstruction, as water, highwayor railway and having a track or passageway forcarrying traffic or other moving loads and havingan opening measured along the center of theroadway of more than 6.00 meters betweenundercopings of abutments or springlines ofarches or extreme ends of openings for multipleboxes; it may include multiple pipes, where theclear distance between openings is less than halfof the smaller contiguous opening.”

Bridge—The term “bridge” is usually reservedfor structures over water courses or canyons.

Overpass—A structure carrying the principalroute over a highway street or railroad.


Part 3 100-2

Underpass—A structure which provided forpassage of the principal route under a highway,street, railroad or other feature.

Traffic Interchange—An overpass or underpassis also called a T.I. if on and off ramps areprovided to the intersecting roadway.

Viaduct—A structure of some length carrying aroadway over various features such as streets,waterways or railroads.

Tunnel—A structure carrying a roadway througha hill or mountain.

Pedestrian Overpass—A structure carrying apedestrian walkway over a roadway.

Pedestrian Underpass—A structure whichprovides for passage of a pedestrian walkwayunder a roadway.

102 DESIGN FEATURES

102.01 GENERAL

The general features of design shall be asspecified in Section 2 of AASHTO except asclarified or modified in this manual.

102.02 DESIGN METHODS

ALL BRIDGE MEMBERS ARE TO BEDESIGNED IN ACCORDANCE WITHAASHTO AND THE REQUIREMENTS OFTHIS MANUAL. (Other standards may beallowed with Department approval.)

102.03 VERTICAL CLEARANCE ATSTRUCTURES(AASHTO 2.2.3)

The following are minimum vertical clearancestandards for highway traffic structures,pedestrian overpasses, railroad overpasses,tunnels and sign structures. Lesser clearancesmay be used only under very restrictiveconditions, upon individual analysis and with theapproval of the Abu Dhabi Roads Section ProjectManager.

102.03.01 Highway Traffic Structures

The design vertical clearance to structurespassing over Freeways, Highways and all Ruraland Urban Arterials shall be at least 6.00 metersover the entire roadway width, including auxiliarylanes and shoulders. An allowance of 150millimeters is included to accommodate futureresurfacing. This allowance may be waived if theroadway under the structure is surfaced withportland cement concrete.

The design vertical clearance to structurespassing over all other highways and streets shallbe at least 5.50 meters over the entire roadwaywidth, including auxiliary lanes and shoulders.An allowance of 150 millimeters is included toaccommodate future resurfacing. This allowancemay be waived if the roadway under the structureis surfaced with portland cement concrete.

Certain routes have been designated as truckroutes. On these routes, larger vertical clearancemust be maintained. For future projects, theseroutes will be identified by the Abu Dhabi RoadsSection Project Manager during the conceptstage.

102.03.02 Pedestrian Overpasses

Because of their lesser resistance to impacts, theminimum design vertical clearance to pedestrianoverpasses shall be 6.00 meters regardless of thehighway system classification. An allowance of150 millimeters is included to accommodatefuture resurfacing.

102.03.03 Railroad Overpasses

Structures over railways shall provide a minimumclearance of 7.00 meters above top of rail, exceptthat overhead clearance greater than 7.00 metersmay be approved when justified on the basis ofrailroad electrification. No additional allowanceshall be provided for future track adjustments.


Part 3 100-3

102.03.04 Tunnels

The minimum design vertical clearance fortunnels shall be at least 6.00 meters for freewaysand arterials and at least 5.50 meters for all otherhighways and streets.

102.03.05 Sign Structures

Because of their lesser resistance to impacts, theminimum design vertical clearance to signstructures shall be 6.00 meters regardless of thehighway system classification. An allowance of150 millimeters is included to accommodatefuture resurfacing.

102.03.06 Width (AASHTO 2.3.1)

The horizontal clear width for rural bridges whereapproach guardrail is used shall provide anadditional width on each side of the approachroadway width to allow the bridge rail to line upwith the approach guardrail. The horizontal clearwidth for urban bridges, in which curb and gutterand/or sidewalks are used, shall equal theapproach roadway width.

102.04 RAILINGS (AASHTO 2.7)

In general, concrete barrier should be used as avehicular railing. For situations requiring adifferent barrier type, only FHWA crash testapproved bridge rails are allowable alternatives.

Bridge rails shall be constructed vertical.Concrete barriers shall not be slipformed. Forcast-in-place, post-tensioned concrete bridges,barriers shall be cast after post-tensioning andmay be cast before falsework removal.

102.05 CONCRETE BARRIERTRANSITIONS

Transitions from bridge concrete barrier toapproach guardrail should, when practical, belocated on the bridge, approach slab orwingwalls.

102.06 APPROACH SLABS

Concrete approach slabs shall be used on allstructures. Approach slabs serve a dual purposeof providing a transition structure from the bridgeto the approach roadway should the roadwayembankment settle and of eliminating the live loadsurcharge of the abutment backwall when theconditions specified in AASHTO 3.20.4 aresatisfied. Approach slabs are to be designedusing the Service Load Design Method and shallcover the entire roadway width including theshoulders, from wingwall to wingwall.

102.07 ANCHOR SLABS

When approach roadways are paved withportland cement concrete pavement (PCCP),adequate means shall be provided to preventpavement growth from causing damage to thebridge. Use of a properly designed anchor slab isone means of providing such protection

102.08 DECK DRAINAGE

On grade separation structures, roadway drainsshall not discharge water onto unprotectedembankment slopes or within five meters of thetraveled roadway below, nor shall drains belocated less than 1.5 meters from the centerlinesof abutments or piers. In urban areas collectionof deck drainage in a pipe system may berequired, with down drains in or on pier columnsdischarging into storm drainage collector systems.Consideration should always be given to providecollector drains and discharge systems on theapproach roadway gutter rather than on thebridge.

For bridges with sidewalks, expansion joints shallbe turned up at the curb line to prevent roadwaywater from entering sidewalk areas. Appropriatemeans shall be taken to ensure that sidewalkdrainage does not pond and that the water doesnot escape around the wing walls and erode theembankment.

For deck drainage design criteria, refer to theROADWAY DESIGN MANUAL - Drainage.


Part 3 100-4

102.09 WING WALLS

Wing walls shall extend 1.50 meters beyond thecatch point, where catch point is defined as theintersection of the fill slope in front of theabutment with the finished approach grade at theoutside face of the wing wall. The bottom of thewing walls shall be embedded a minimum of 1meter into the approach fill at the end of the wingwalls.

102.10 LIGHTING

Consideration shall be given to special lightingabove and below the structure. This lighting shallserve as ornamental lighting to enhance theaesthetics and also to enhance safety. Thislighting is in additional to the normal roadwaylighting. Refer to the lighting section of thismanual for roadway lighting criteria.Coordination of all structure lighting with existingand/or planned lighting of connecting andadjacent roads must be considered.

102.11 BRIDGE DECK ELEVATIONS

The project design group shall prepare eithercomputer plotted contours at 0.1 meter intervalsat a 1:50 scale or tabulate elevations at 3.0 meterintervals along the profile grade line, withadditional elevation points on each perpendicular(radial) such that the bridge can be completelycovered with 0.1 meter contours. The number ofelevation points on each perpendicular must besuch that the lowest, or the highest, point isoutside the bridge for use by the constructionsupervision staff to help check the contractor’sgeometric layout.

102.12 CONCRETE CRACK CONTROL

Maximum flexural crack width at the tensile faceof a reinforced concrete section shall not exceed0.25mm for normal conditions of exposure and0.20mm for marine and unfavorable conditions ofexposure (such as alternate wetting and drying,humid atmosphere, direct contact with soil, etc.).The allowable crack width can be increased by25% under earthquake/wind/temporaryconstruction conditions.

102.13 CORROSION PROTECTION(AASHTO 8.22)

Due to the adverse corrosive environment, allreinforced concrete structures shall use epoxycoated rebar unless otherwise directed by theProject Manager.

103 ARCHITECTURALCONSIDERATIONS

103.01 PROCEDURE

Following the approval of the civil and basicstructural concepts for an interchange, includingconfiguration, alignment, profile and pierlocations, the Project Design Manager will meetwith the Structural, Architectural, and GraphicsDesign Managers to develop basic alternativesand set architectural design parameters.Environmental constraints and influences will beestablished. The Concept Design Team willdetermine the number of structural concepts andarchitectural options to be studied. The purposeof these studies will be do develop applicableconcepts and options in the form of presentationdisplays, to be used as a basis for the Abu DhabiRoads Section review and decision making. Theapproved displays are submitted to the AbuDhabi Roads Section for review and selection ofthe desired alternative. The approved scheme thewill progress to the preliminary and final designphases.


Part 3 100-5

103.02 GENERAL CRITERIA

Every effort should be made in the treatment ofstructures to respect the Islamic design andculture.

Design concepts should be easily implemented.Construction considerations are also taken intoaccount in the architectural treatment concepts.Architectural elements should be functional,durable and easily maintained.

Each structure should have individuality;however, a totally different design is not requiredfor each structure. It is desirable to maintain asense of continuity throughout the wholeprogram.

Architectural treatment should be continuousthrough an interchange.

In the downtown area, underpasses spanning agiven roadway should have similar treatment toestablish continuity. Decorative and medianlighting should be similar on overpasses along agiven route.


Part 3 200-1

SECTION 200DESIGN LOADS

201 LOAD TYPES

201.01 GENERAL

Loads shall be as specified in Section 3 ofAASHTO except as clarified or modified in thismanual.

201.02 DEAD LOADS (AASHTO 3.3.1)

Utility loads shall be included as applicable.

201.03 FUTURE WEARING SURFACE(AASHTO 3.3.3)

All new structures shall be designed to carry anadditional dead load of 120 kg/m2 from curb tocurb of roadway to allow for a future wearingsurface. This load is in addition to any wearingsurface which may be applied at the time ofconstruction. The weight of the future wearingsurface shall be excluded from the dead load fordeflection calculations.

201.04 WEARING SURFACE(AASHTO 3.3.5)

The top 15 millimeters of the deck shall beconsidered as a wearing surface. The weight ofthe wearing surface shall be included in the deadload but the 15 millimeter shall not be included inthe depth of the structural section for all strengthcalculations including the deck, superstructureand the pier cap, where appropriate.

201.05 HIGHWAY LOADS(AASHTO 3.7.1.1)

P Loads (permit design live loads) are specialvehicular loads that will be applied only tospecific structures, such as interchange ramps,and at the direction of the Abu Dhabi RoadsSection.

201.06 STRUCTURE LOADINGS

1. Highway Bridge Live Load: AASHTO 20-44increased by 25 percent.

2. Wind Velocity: 160 kilometers per hour.3. Humidity Range: 25 percent to 100 percent.4. Earth Pressure: For specific project

recommendations, refer to Soils Report5. Future Utilities: 75 kg/m² of Bridge Deck.6. Earth Weight: 1920 kg/m3

7. Earthquake Loading: Only to be consideredif directed by the Road Section ProjectManager.

201.07 FRICTION FORCES(AASHTO 3.9.2)

Friction forces due to elastomeric bearing pads orTFE surfaces shall be based on theManufacturer’s data for the bearing used.

201.08 THERMAL FORCES(AASHTO 3.16)

1. Temperature Range: 70ºC.2. Temperature Fall: 30ºC to 0ºC = 30ºC.3. Temperature Rise: 30ºC to 70ºC = 40ºC.4. The temperature gradient between the top

slab and bottom slab of concrete box girderbridges is 20ºC.

201.09 STREAM FORCES(AASHTO 3.18.1)

A Drainage Report shall be produced by BridgeDrainage Section or a consultant, whenappropriate, for all stream and/or channelcrossings. The designer should review theDrainage Report for a full understanding ofwaterway considerations. The report shouldcontain as a minimum, the following informationfor both the critical flow and superfloodconditions: • High water elevation• Mean Velocity• Scour Elevations (General and Local)• Angle of attack• Required bank protection• Special drainage considerations• Horizontal and Vertical Clearances


Part 3 200-2

• Direction of Flow

For design for the most critical flow and thesuperflood condition, the following criteria shallbe used unless more severe criteria isrecommended in the Drainage Report.

Design calculations of stream forces on piers overnatural water courses shall assume a 0.6 meterincrease in pier width per side due to blockage bydebris with a shape factor k = 1.40 for the first3.5 meters of depth. For flows with depthsgreater than 3.5 meters, only the top 3.5 metersshall be assumed blocked by debris with lowersections using the actual pier width and a shapefactor in accordance with AASHTO. Foruncased drilled shafts, a 20% increase in diametershould be assumed to account for possibleoversizing of the hole and any irregular shape.The force distribution on the pier shall beassumed to vary linearly from the value at thewater surface to zero at the bottom of the scourhole as described in AASHTO.

When the clear distance between columns orshafts is 5.00 meters or greater, each column orshaft shall be treated as an independent unit forstream forces and debris. When the clear distanceis less than 5.00 meters the greater of the twofollowing criteria shall be used: 1) Each columnor shaft acting as an independent unit or 2) Allcolumns or shafts acting as one totally cloggedunit with 0.6 meters of debris normal to the flowadded on each end.

The average main channel velocity for theappropriate flow condition shall be used incalculating the stream forces. The water surfaceelevation shall be the high water elevation for theappropriate flow condition. A minimum angle ofattack of 15 degrees shall be assumed.

Scour may be categorized into two main types:general and local. General scour is the permanentloss of soil due to degradation or mining whilelocal scour is the temporary loss of soil during apeak flow. Local scour may consist of two types:contraction scour and local pier or abutmentscour. Contraction scour occurs uniformly across

the bridge in the stream width. Local pier andabutment scour occurs locally at substructureunits due to the turbulence caused by the presenceof the substructure unit.

Bridges over natural water courses shall beinvestigated for four different streambed groundlines. Refer to Figure 200.01 for an illustrationof these cases.

Case 1 represents the “as-constructed” streamcross section. For this case, the bridge shall bedesigned to withstand the forces from theAASHTO Groups I to VII load combinations.

Case 2 represents the long term dry streambedcross section, i.e. the “as-constructed” streamcross section minus the depth of the generalscour. For this case, the bridge shall be designedto withstand the same forces as for Case 1. Therequirements contained in AASHTO 4.4.5.2 neednot be met.

Case 3 represents the streambed cross sectioncondition for the most critical design flow.Abutment protection is designed to withstand thisevent and abutments may be assumed to beprotected from scour for this condition. Piers willexperience the full general and critical flow localscour. For this case, the bridge shall be designedto withstand the forces from the AASHTOGroups I to VI load combinations.

Case 4 represents the streambed cross sectionconditions for the superflood condition. For thiscase, all bank protection and approachembankments are assumed to have failed.Abutments and piers should be designed for thesuperflood scour assuming all substructure unitshave experienced the maximum scoursimultaneously. For this case, the bridge shall bedesigned to withstand the following forces: DL +SF + B + 0.5W. For members designed using theWSD Method an allowable overstress of 140%shall be used. For members designed using theLFD Method a gamma factor of 1.25 shall beused.


Part 3 200-3

Figure 200.01Groundline Variations Due to Scour

201.10 LATERAL EARTH PRESSURE(AASHTO 3.20.1)

For backfills compacted in conformance with theStandard Specifications, active pressure forunrestrained walls should be calculated using aninternal angle of friction of 33 degrees unlessrecommended otherwise in the GeotechnicalReport.

201.11 DIFFERENTIAL SETTLEMENT(AASHTO 3.3.2.1)

Differential settlement shall be considered in thedesign when indicated in the Geotechnical Report.The Geotechnical Report should provide themagnitude of differential settlement to be used inthe design. If not addressed in the GeotechnicalReport, and at the direction of the

Roads Section Project Manager, a minimumdifferential settlement of 25mm may be used inthe design.

Differential settlement, if required, shall beconsidered the same as temperature and shrinkageforces and included in Group IV, V and VI loadcombinations.

201.12 EARTHQUAKES(AASHTO 3.21)

Earthquake criteria will only be considered in thedesign process at the direction of the RoadSection Project Manager. If so directed, referenceis made to AASHTO Division 1-A.


Part 3 200-4

202 DISTRIBUTION OF LOADS

Loads shall be distributed as specified in Section3 of AASHTO except as clarified or modified inthis manual.

202.01 SUPERIMPOSED DEADLOADDISTRIBUTION(AASHTO 3.23.2.3.1.1)

The weight of curbs, barriers and sidewalks foran I-Girder bridge with composite concrete deckshall be distributed as follows:

i) Equally over all girdersii) Equally over all girders under the sidewalkiii) If there is no sidewalk, curb and barrier shall

be distributed 60% to the exterior girders and40% to the interior girders.

Each girder shall be designed for the conditionthat causes highest stresses. Girders shall in noway be designed for loads less than that specifiedin AASHTO Section 3.

202.02 CONCRETE BOX GIRDERS(AASHTO 3.23.2.3.2.2)

In calculating the number of lanes of live load onthe superstructure, the entire cross section of thesuperstructure shall be considered as one unitwith the number of lanes of live load equal to theout-to-out width of the deck in meters divided by4.27. Do not reduce this number for multiplelanes as specified in AASHTO 3.12.1 nor roundto a whole number as specified in AASHTO3.6.3.

202.03 PRESTRESSED VOIDED SLABS(AASHTO 3.23.4.3)

The equations for distribution of live loadcontained in the Fifteenth Edition (1992)including the 1993 and 1994 Interims shall not beused. The new distribution factors in the latestedition, initially changed in the Fourteenth Edition(1989), are based on tests on T-beams and are notdeemed appropriate for voided slabs or boxbeams. Instead, the equations in the ThirteenthEdition (1983) as repeated below shall be used todistribute live loads:

In calculating bending moments in multi-beamprecast concrete bridges, conventional orprestressed, no longitudinal distribution of wheelload shall be assumed.

The live load bending moment for each sectionshall be determined by applying to the beam thefraction of a wheel load (both front and rear)determined by the following relations:

Load Fraction = S D

Where

S = 12 NL + 9 Ng

D = 5 + NL + ( 3- 2NL ) ( 1-C ) 2 when C<3 10 7 3

D = 5 + NL when C>3 10

NL = total number of traffic lanes fromAASHTO Article 3.6

Ng = number of longitudinal beamsC = K(W/L), a stiffness parameter

W = overall width of bridge in meters

L = span length in meters

Values of K To Be Used in C = K(W/L)

Bridge Type Beam Type KMulti-Beam Non-Voided Rect 0.7 Rect. w/ Circular Voids 0.8 Box Section 1.0

Channel 2.2

202.04 PRESTRESSED BOX BEAMS(AASHTO 3.23.4.3)

The equations for distribution of live loadcontained in the Fifteenth Edition (1992)including the 1993 and 1994 Interims, shall notbe used. Refer to Distribution of Loads inSection 202.02 of this manual for criteria ondistribution of loads.


Part 3 200-5

202.05 LATERAL TENSIONING OFMULTI-BEAM UNITS(AASHTO 3.23.4.1)

Each lateral tensioning tie shall consist of a 38millimeter diameter mild steel bar tensioned to13,560 kg. Tension in the 38 millimeter diametermild steel should be applied by the turn of nutmethod. The designer should determine thenumber of turns of the nut required to achieve the13,560 kg force. This value should be shown onthe plans.

A36M steel bars for the tie normally come in 6meter lengths. the final total length of the tieshould be made using threaded couplers; notwelded splices. When couplers are used, the holethrough the diagram should be increased from thenormal 64 millimeter to 102 millimeter diameterto accommodate the couplers.

Adequate means shall be used to ensure that theties are adequately protected from corrosion. therod, nut and bearing plate shall be galvanized inaccordance with ASTM A153 (AASHTO M-232).

202.06 LIVE LOAD DISTRIBUTION(AASHTO 3.6.3 AND 3.12.1)

In designing the superstructure, the live loaddistribution factors shall not be reduced formultiple lanes as specified in AASHTO 3.12.1 orrounded to a whole number as specified inAASHTO 3.6.3. These two reductions apply tosubstructure design only.

203 LOAD FACTORS

An essential feature of Load Factor Design (LFD)requires raw design loads or related internalmoments and forces to be modified by specifiedload factors (γ, gamma and β, beta), andcomputed material strengths to be reduced byspecified reduction factor (φ, phi).

These are safety factors which ensure certainmargins for variation. The three different kindsof factors are each set up for a distinct purpose,each independent of the other two. In this way,any one of them may be refined in the futurewithout disturbing the other two.

1. γ(Gamma) Factor

The γ (gamma) factor is the most basic of thethree. It varies in magnitude from one loadcombination to another, but it always applies toall the loads in a combination. Its main effect isstress control that says we do not want to usemore than about 0.8 of the ultimate capacity. Itsmost common magnitude, 1.3 lets us use 77%.Earthquake loads are not factored above 1.0because we recognize that stresses in the plasticrange are allowed, as long as collapse does notoccur.

An example may be given to justify the use ofgamma of 1.3 for dead load. Assuming the liveload being absent, the probable upper value of thedead load could be a minimum of 30% greaterthan calculated. For a simple structure thispercentage may be as follows:

10% due to excess weight. 5% due to misplaced rebar 5% structure behavior approximation10% stress increase (actual vs. calcs.)30% Total variation assumed to occur

concurrently at the section most heavily stressed.

2. β (Beta) Factor

The second factor, β(beta), is a measure of theaccuracy with which we can predict various kindsof loads. It also reflects the probability of oneload’s simultaneous application with others in acombination. It applies separately, with differentmagnitudes, to different loads in a combination.For example, it is usually 1.0 for dead load. Itvaries from 1.0 to 1.67 for live loads and impact.

Due regard has been given to sign in assigningvalues to beta factors, as one type of loading mayproduce effects of opposite sense to that producedby another type. The load combinations withβD=0.75 are specifically included for the casewhere a higher dead load reduces the effects ofother loads.


Part 3 200-6

The beta factors for prestressing force effects areset so that when multiplied by the respectivegamma factor, the product is unity. Beta of 1.67for live load plus impact from H loads reflectsAASHTO’s way of handling permit loads.

3. φ (Phi) Factor

φ(phi), the third factor, relates to materials and iscalled either a capacity reduction factor or astrength reduction factor. Its purpose is toaccount for small adverse variations in materialstrength, workmanship, and dimensions. Itapplies separately to different magnitudes forvarious load effects in reinforced concrete, andvarious manufacturing processes in prestressedconcrete. Since φ relates to materials rather thanloads, its values are given in the various materialspecifications. For structural steel it is almostalways 1.0. For concrete it varies from 0.7 to1.0.


Part 3 300-1

SECTION 300REINFORCED CONCRETE

301 GENERAL

Reinforced concrete design criteria shall be asspecified in Section 8 of AASHTO except asclarified or modified in this manual.

301.01 CONCRETE (AASHTO 8.2)

Concrete for highway structures shall have thefollowing minimum cylinder strengths, unlessotherwise directed by the Project Manager:

Decks except barriers f ′c = 280 kg/cm2

Abutments f ′c = 210 kg/cm2

Piers except footings f ′c = 280 kg/cm2

Drilled Shafts f ′c = 280 kg/cm2

All other f ′c = 210 kg/cm2

For Design Load use Concrete Weight = 2500kg/m3

• Class K 250 Concrete Design Parameters

f ′c = 210 kg/cm2

fc = 80 kg/cm2

Ec = 220 000 kg/cm2


f ′c = 280 kg/cm2

fc = 110 kg/cm2

Ec = 255 000 kg/cm2


f ′c = 350 kg/cm2

fc = 140 kg/cm2

Ec = 283 000 kg/cm2

301.02 DIAPHRAGMS (AASHTO 8.12.3)

Reinforced concrete box girder diaphragm criteriashall be the same as for post-tensioned boxgirders as specified under Diaphragms in Section402.06 of this manual.

301.03 DESIGN METHODS(AASHTO 8.14.1)

In accordance with the applicable provisions ofAASHTO, the Strength Design Method (LFD)shall be used for the design of all reinforcedconcrete members except where such membersare to be below grade or intended for waterretention, then the Service Load Design Methodshall be used.

301.04 REINFORCEMENT(AASHTO 8.15.2.2)

Concrete shall be reinforced only with fusionbonded epoxy coated reinforcement steelconforming to AASHTO M 31M (ASTMA615M) Grade 400 as follows:

• Deformed Round Steel Bar Reinforcement,AASHTO M 31M Grade 400

fy = 4 080 kg/cm2

fu = 6 120 kg/cm2

fs = 1 680 kg/cm2 T or C in beamsEs = 2 039 470 kg/cm2

• Spiral Reinforcement and Welded WireFabric

Steel Bars used as Spirals, AASHTO M31M Grade 400

Steel Wire used as Spirals, AASHTO M32

Welded Wire Fabric used as reinforcementin concrete and mortar, AASHTO M 55

302 SLAB DESIGN

Slabs shall be designed in accordance with thecriteria specified in Section 3 of AASHTO exceptas clarified or modified below.

All reinforcing bars are to be epoxy coated bars.All reinforcing bars shall be straight bars top andbottom. The use of truss bars will not bepermitted.


Part 3 300-2

For skews less than or equal to 20 degrees thetransverse bars shall be placed parallel to theskew. For skews greater than 20 degrees thetransverse bars shall be placed normal to thegirders.

Use of steel stay-in-place forms should beconsidered during design for steel girder orprecast girder bridges for special conditions only.Some circumstances which warrant suchinvestigation include: bridges over heavilytraveled roads, bridges over live streams andbridges over deep canyons. A discussion on theiruse shall be made in the Design Concept Report.If use of steel stay-in-place forms is notrecommended during design, they will not beallowed during construction due to the extra deadload. Contractor requests for usage duringconstruction will not be approved.

302.01 SPAN LENGTHS(AASHTO 3.24.1.2)

The deck slab span length for AASHTOgirders shall be the clear distance between thetop flanges plus one-half the flange width.

302.02 SLAB THICKNESS(AASHTO 8.11.1)

The thickness of new deck slabs shall bedesigned in 10 millimeter increments with theminimum thickness as shown below, unlessotherwise directed by the Project Manager.

Slab ThicknessS(m) t(mm)

Up to 1.800 1901.801 to 2.100 2002.101 to 2.400 2102.401 to 2.700 2202.701 to 3.000 2303.001 to 3.300 2403.301 to 3.600 2503.601 to 3.900 260

Where S = Design span as defined in AASHTO3.24.1 and above.

t = Minimum thickness of deck slab.

302.03 PROTECTION AGAINSTCORROSION(AASHTO 8.22.1)

The minimum clearance for top reinforcing innew decks shall be 50 millimeters with 50millimeter Asphaltic wearing surface and theminimum specified concrete strength (f ′c) shallbe 280 kg/cm2.

302.04 DISTRIBUTION METHOD(AASHTO 3.24.3)

Use the AASHTO method for load distributionon slabs except for unusual loads or unusualstructures such as single cell boxes.

302.05 RAILING LOADS(AASHTO 3.24.5.2)

When barriers are located at the deck edge, thedeck shall be designed to resist both the axialforce and the bending moments due to all deadloads and horizontal rail load or due to all deadloads plus vertical wheel loads, whichever iscritical.


Part 3 400-1

SECTION 400PRESTRESSED CONCRETE

401 DESIGN CRITERIA

401.01 GENERAL

Prestressed design criteria shall be as specifiedin Section 9 of AASHTO except as clarified ormodified in this manual.

Members shall be designed to meet both ServiceLoad Design and Strength Design (Load FactorDesign) criteria as specified in AASHTO.

Prestressing steel for precast prestressedmembers and cast-in-place post-tensionedmembers shall be 12.50 millimeter diameter"Uncoated Seven-wire High Tensile ColdDrawn Low Relaxation Strand for PrestressedConcrete" as specified in ASTM A416, Grade270 with f ′c = 18 360 kg/cm2 and Eps = 2039 470 kg/cm2. Use of 15.20 millimeterdiameter strand is allowed for cast-in-placepost-tensioned members only.

The yield point stress of prestressing steel, f*y,may be assumed equal to 0.90 f ′c for lowrelaxation strand.

Prestress losses shall be calculated in accordancewith AASHTO Article 9.16.2.1. The estimatedlosses contained in Table 9.16.2.2 and Article9.16.2.2 shall not be used.

Section properties shall be based on gross area ofmembers. Use of the transformed area of bondedreinforcement shall only be used for unusualstructures and only when approved.

Web reinforcement for shear shall consist ofrebars; not welded wire fabric.

The minimum top cover for slab reinforcementspecified in AASHTO Article 9.25.1.2.1 shall be50 millimeters with 50 millimeter Asphalticwearing surface.

Expansion and contraction design criteria shall beas specified in Part 3, Section 600 of this manual.

401.02 ALLOWABLE STRESSES—CONCRETE (AASHTO 9.15.2.2)

The maximum allowable tensile stresses in aprecompressed tensile zone at service load afterlosses have occurred shall be in accordance withAASHTO except as modified below:

TensionLoad Condition AllowableStressGirder DL + Prestress 0Total Service Load 0.8 ƒ 'c

401.03 SHEAR (AASHTO 9.20)

Shear design shall be in accordance withUltimate Strength Design Method contained inthe latest AASHTO Specifications.

Prestressed concrete members shall bereinforced for diagonal tension stresses. Shearreinforcement shall be placed perpendicular tothe axis of the member with spacing not-to-exceed three-fourths the depth of the member.

The critical sections for shear in simplysupported beams will usually not be near theends of the span where the shear is a maximum,but at some point away from the ends in aregion of high moment.

For the design of web reinforcement in simplysupported members carrying moving loads, it isrecommended that shear be investigated only inthe middle half of the span length. The webreinforcement required at the quarter pointsshould be used throughout the outer quarters ofthe span if the critical shear section is includedwithin the design section.

For continuous bridges whose individual spansconsist of precast prestressed girders, webreinforcement shall be designed for the fulllength of interior spans and for the interiorthree-quarters of the exterior span and based onthe critical shear design section.


Part 3 400-2

402 POST TENSIONED BOXGIRDER BRIDGES

402.01 GENERAL

Post-Tensioned Box Girder Bridges shall bedesigned in accordance with AASHTOspecifications. Girders shall be designed byWorking Stress Method and checked by theUltimate Strength Method (Load Factor Design).The deck slab is to be designed by the WorkingStress Method.

402.02 CONCRETE(AASHTO 9.2 AND 9.22)

The following concrete strengths are the desiredstrengths to be used. Higher strengths may beused if approved by the Abu Dhabi Roads SectionProject Manager.

Initial f ′c = 290 kg/cm2 minimum.

Final f ′c = 350 kg/cm2 minimum f ′c = 420 kg/cm2 maximum

402.03 BEARING PADS

Allow an extra 80mm movement per 100 metersof girder length for long-term creep andshortening due to post-tensioning.

402.04 CREEP AND SHRINKAGE(AASHTO 9.4)

For restrained members in continuous bridgeswhere shortening due to post-tensioning inducesmoments and shears, a shrinkage and creepcoefficient of 1.5 shall be used for design ofsubstructure elements with the total movementequal to 1.5 times the initial shortening. Forsuperstructure elements, no creep factor should beapplied except for long term deflectionconsiderations.

402.05 FLANGE AND WEBTHICKNESS - BOX GIRDERS(AASHTO 9.9)

Minimum top slab thickness shall be 200millimeters. Minimum bottom slab thicknessshall be 150 millimeters. Minimum webthickness shall be 300 millimeters (measured

normal to girder for sloping exterior webs).Interior webs shall be constructed vertical.

402.06 DIAPHRAGMS (AASHTO 9.10)

A single 250 millimeter thick intermediatediaphragm shall be placed at the midspan for allbridges. Special consideration for additionaldiaphragms should be given to box girders withlarge skews, curved boxes and boxes over 2meters in depth. Diaphragms shall be placedparallel to abutments and piers for skews lessthan or equal to 20 degrees and normal to girdersand staggered for skews over 20 degrees.Diaphragms shall be cast integral with girderwebs.

402.07 DEFLECTIONS (AASHTO 9.11)

The deflection shall be calculated using dead loadincluding barriers, but not the future wearingsurface, gross section properties and calculatedfinal losses. The additional long term deflectionshall be calculated by multiplying the deflectionby two. An additional parabolic shapeddeflection with a peak equal to 30 millimeters per100 meters should be added to the total deflectionfor simple spans. The final long term deflectionshall be the sum of the deflection, the additionallong term deflection and the additional deflectionfor simple spans. The camber shown on the plansshall be the final long term deflection.

402.08 ALLOWABLE STRESSES -PRESTRESSING STEEL(AASHTO 9.15.1)

In calculating the stress in the prestressing steelafter seating, the friction and anchor set lossesonly should be included. For post-tensionedmembers, overstressing for short periods of timeto offset seating and friction losses is permittedbut the maximum allowable jacking stress for lowrelaxation strand shall be limited to 0.78 f ′s.

402.09 ALLOWABLE STRESSES-CONCRETE (AASHTO 9.15.2)

In calculating the temporary stress in the concretebefore losses due to creep and shrinkage, thefriction, anchor set and elastic shortening lossesshould be included.


Part 3 400-3

Special consideration shall be given to bridgessupported on falsework with large openings wheredeflections could be harmful to the structure.Unless falsework requirements are strengthenedor other means taken to ensure the bridge does notform tension cracks prior to tensioning, themaximum allowable tension in a precompressedtensile zone shall be limited to zero.

402.10 LOSS OF PRESTRESS(AASHTO 9.16)

For multi-span bridges, the cable path shouldhave its low point at the midspan. Design shouldbe based on usage of galvanized rigid ducts withK = 0.00000066 and µ = 0.25. Anchor set lossesshould be based on 16 millimeter set.

For creep of concrete, the variable fcds should becalculated using the total dead load applied afterprestressing, including the 120 kg/m2 futurewearing surface.

402.11 FLEXURAL STRENGTH(AASHTO 9.17)

In determining the negative ultimate momentcapacity, the top layer of temperature andshrinkage and bottom layer of distributionreinforcing may be used. In determining thepositive ultimate moment capacity, thelongitudinal flange reinforcing (AASHTO 9.24)may be used.


Girder webs will be designed for shear using theUltimate Strength Method according to the 1979Interim AASHTO Standard Specifications. Themaximum girder web stirrup spacing will be 300mm within 6 meters from the front face of theabutment diaphragms. This will eliminate theneed for re-spacing the web stirrups at the pointof web flare if the post-tensioning system requiresflaring.

The value of "d" to be used in shear calculationsshall be the larger of the calculated "d" value or0.8 times the overall effective depth.

Horizontal shear shall be investigated inaccordance with the provisions of AASHTO9.20.4.

Calculations shall include the shear due tosecondary moment and cable shear. For curvedbox girder bridges, the shear due to torsion shallbe included.

402.13 FLANGE REINFORCEMENT(AASHTO 9.24)

Reinforcing in the bottom slab of box girdersshall conform to the provisions of AASHTO8.17.2.3 except that the minimum distributedreinforcing in the bottom flanges parallel to thegirders as specified in AASHTO 8.17.2.3.1 shallbe modified to be 0.30 percent of the flange area.

402.14 METHOD OF ANALYSIS

The superstructure may be designed using thesystem as described below:

1) The bottom slab, in the vicinity of theintermediate support, may be flared toincrease its thickness at the face of thesupport when the required concrete strengthexceeds 320 kg/cm2. When thickened, thebottom slab thickness should be increased bya minimum of 50 percent. The length of theflare should be at least one-tenth of the spanlength (measured from the center of thesupport) unless design computations indicatethat a longer flare is required.

2) Section properties at the face of the supportshould be used throughout the support; i.e.the solid cap properties should not beincluded in the model.

3) Negative moments should be reduced toreflect the effect of the width of the integralsupport.

4) Dead load forces should not produce anytension in the extreme fibers of thesuperstructure.

5) The superstructure should be designed as aunit with the number of live loads applied inaccordance with Section 202.02 of thismanual.

For box girders with severe sloping webs orboxes over 2 meter deep, transverse flangeforces induced by laterally inclined longitudinalpost-tensioning shall be considered in the design.


Part 3 400-4

Single span structures should be jacked from oneend only. Symmetrical two span structures maybe jacked from one end only or jacked from bothends. Unsymmetrical bridges should be jackedfrom one end or both ends as required by thedesign. Three span or longer structures shouldbe jacked from both ends.

Several prestressing systems should be checkedto verify that the eccentricity and anchoragedetails will work. In determining the center ofgravity of the strands, the Z factor, the differencebetween the center of gravity of the strands andthe center of the ducts, shall be considered. Forstructures over 120 meters in length, indetermining the c.g. of the strands, the diameterof the ducts should be oversized by 13millimeters to allow for ease of pulling thestrands.

For horizontally curved bridges, special careshall be taken in detailing stirrups and duct ties.Friction losses should be based on both verticaland horizontal curvatures. In designing forhorizontal curvature, the exterior web with thesmallest radius shall be used. Consideration tothe ± 5% variation allowed per web shall beincluded.

403 PRECAST PRESTRESSEDCONCRETE

403.01 CONCRETE (AASHTO 9.2)

Concrete for highway structures shall have aminimum specified initial and final concretestrengths as shown below. Higher strengthconcrete may only be used when required bydesign and when approved.

Initial f ′ci = 290 kg/cm2 Minf ′ci = 320 kg/cm2 Max

Final f ′c = 360 kg/cm2 Minf ′c = 420 kg/cm2 Max

403.02 DEFLECTIONS (AASHTO 9.11)

The Release, Initial and Final Deflections shall beshown on the plans. Deflections shall be shownin centimeters at the tenth points.

The Release Deflection equals the deflection theprestress girder undergoes at the time of strandrelease. The Release Deflection includes the deadload of the girder and the release prestressingforce (including the effects of elastic shortening).

The Initial Deflection equals the deflection theprestress girder undergoes at the time of erectionprior to the diaphragm or deck pours. The InitialDeflection includes the deflection due to the deadload of the girder, the initial prestressing and theeffects of creep and shrinkage up to the time oferection. The time of erection should be assumedto be 60 days after release.

The Final Deflection equals the deflection due tothe dead load of the deck slab, diaphragms andbarriers and the effects of long term creep on thecomposite girders. The effects of the 120 kg/m2

future wearing surface shall be excluded fromdeflection calculations.

Minimum build-up at the edge of Type III girdersand smaller shall be 15 millimeters. For Type IV,V and VI girders the minimum build-up shall be25 millimeters. This minimum build-up at thecritical section will ensure that the flange of thegirder will not encroach into the gross depth ofthe slab.

The tops of the erected girders shall be surveyedin the field prior to placement of the deckforming. If the tops of the erected girderelevations are higher than the finish grade pluscamber elevations minus deck slab and buildupthickness, adjustments will have to be made in theroadway profile or in the girder seat elevations.Encroachment into the slab of up to 15millimeters will be allowed for randomoccurrences.

403.03 ALLOWABLE STRESSES-PRESTRESSING STEEL(AASHTO 9.15.1)

For pretensioned members, overstressing theprestressing steel above the initial stressing limitfor short periods of time to offset seating losses isnot permitted.


Part 3 400-5

403.04 ALLOWABLE STRESSES-CONCRETE (AASHTO 9.15.2)

In calculating the temporary stress in concretebefore losses due to creep and shrinkage, the steelrelaxation prior to release and the elasticshortening should be included.

403.05 LOSS OF PRESTRESS(AASHTO 9.16)

For creep of concrete, the variable fcds, should becalculated using the total dead load applied afterprestressing including the 120 kg/m2 futurewearing surface.

For girders with required concrete releasestrengths of 320 kg/cm2 or less, the time ofrelease may be assumed to be 18 hours. Forspecified strengths over 320 kg/cm2 the time ofrelease should be increased accordingly. Forprecast girders, the final losses shall includerelease losses.

The value of relative humidity to be used incalculating shrinkage losses, shall be the value ofrelative humidity at the bridge site.


The value of "d" to be used in shear calculationsshall equal the depth of the beam plus theeffective depth of the slab with a minimum d =0.80 times the overall depth. The shear shall becalculated assuming full continuity for compositedead load and live load plus impact.

For single span structures, use the shear designspacing at the 1/4 point for sections from the endof the beam to the 1/4 point. For continuousmulti-span structures, use the shear designspacing required from the 1/4 point to the pier forthe section from the 1/4 point to the abutment endto obtain a symmetrical reinforcing pattern for allgirders.


The dead load shall be assumed to be unsupportedand carried by the girders only. Use of maskedstrands for debonding shall not be allowed.

The location of the harped point of the strandshould be located as required by design with thepreferable locations being near the 1/10 of thespan as measured from the midspan of the girder.

404 PRESTRESSED I-GIRDERS

404.01 GENERAL

Precast Prestressed I-Girder Bridges shall bedesigned in accordance with AASHTOspecifications. Girders shall be designed byWorking Stress Method and checked by theUltimate Strength Method (Load Factor Design).The deck slab is to be designed by the WorkingStress Method using a maximum allowable stressof Fc = 110 kg/cm², Class K 335.

The slab and diaphragm dead load is to besupported by the girders only.

The Girders are to be designed as a composite-section, simply-supported beams for Live Loadand Impact and all superimposed dead loads.Negative moment reinforcement is to be designedover the intermediate supports considering spancontinuity and all loads.

Continuity designs will include shrinkage andcreep moments as required by AASHTO Article9.7.2.1.

404.02 CONCRETE

The following concrete strengths are the desiredstrengths to be used. Higher strengths may beused if approved by the Abu Dhabi Roads SectionProject Manager.

Initial f ′ci = 280 kg/cm² minimum. f ′ci = 350 kg/cm² maximum.

Note: 350 kg/cm² release strengths can beusually obtained within 18 hours, but require 4 to6 additional hours for each additional 7 kg/cm²required above 350 kg/cm². Permission isrequired from the Abu Dhabi Roads SectionProject Manager for release strengths above 350kg/cm² and final strengths above 420 kg/cm².

Final f ′c = 350 kg/cm² minimum f ′c = 420 kg/cm² maximum


Part 3 400-6

The maximum allowable stresses are to be inaccordance with AASHTO except as modifiedbelow:

TensionLoad Condition AllowableStressGirder DL + Prestress 0Total Service Load 0.8 ƒ 'c

404.03 EFFECTIVE FLANGE WIDTH(AASHTO 9.8 AND 8.10.1)

The effective flange width will be as specified byAASHTO except for Type V and standard andmodified type VI girders where the requirement of12 times the slab thickness plus web thicknesswill be increased by 430 mm.

404.04 SHEAR

Girders will be designed for shear using the latestAASHTO Standard Specifications. The depth tobe used in the calculation of shear will be thedepth of the beam plus the depth of the of theslab. If composite action is fully developed, theshear will be calculated assuming full continuityfor composite dead load and live load plusimpact.

404.05 INTERMEDIATE DIAPHRAGMS(AASHTO 9.10)

A single 300 millimeter thick intermediatediaphragm shall be placed at the midspan for allspans over 12 meters. For skews less than orequal to 10°, place the diaphragms parallel to theskew. For skews greater than 10º, thediaphragms shall be staggered and placed normalto the girders.

404.06 BEARING PADS

Laminated neoprene bearing pads should be usedfor relatively light reactions and moderatesuperstructure movements.

Pot type bearings should be used for heavyreactions, large superstructure movements andsuperstructure on horizontal curve alignment.

Allow an extra 40 mm movement per 100 metersof girder length for long-term creep andshortening due to prestressing.

Elastomeric bearing pads will be a maximumwidth of 50 mm less than the normal width of thebottom flange to accommodate the 20 mm sidechamfer and should be set back 50 mm from theend of the girder to avoid spalling of the girderends.

404.07 CREEP FACTOR

Use a creep factor of 3 when calculating longterm deflections.

404.08 FRAMES AND CONTINUOUSCONSTRUCTION (AASHTO9.7.2)

Girders shall be designed as composite section,simple supported beams for live load plus impactand composite dead load. The superstructureshall be constructed continuous with the negativemoment reinforcing designed consideringcontinuity over intermediate supports for live loadplus impact and composite dead loads. Thepositive moment connection may be designedusing the method described in the PCApublication "Design of Continuous HighwayBridges with Precast, Prestressed ConcreteGirders". In determining the positive restraintmoment, use 30 days as the length, of timebetween casting the girders and deck closure. Thedevelopment length of the strands may be basedon the criteria contained in Report No. FHWA-RD-77-14, "End Connections of Pretensioned I-Beam Bridges" November 1974. In determiningthe number and pattern of strands extended,preference shall be given to limiting the number ofstrands by increasing the extension length andalternating the pattern to increase constructability.


Part 3 400-7

404.09 DIFFERENTIAL SHRINKAGE(AASHTO 9.13.3.3)

Differential shrinkage should be considered in thedesign when the effects become significant andwhen approved by the Project Manager.


AASHTO Type V and Type VI modified girdersshould be used in place of Type V and Type VIregular girders whenever possible.

The theoretical build-up depth shall be ignored forcalculation of composite section properties.

405 PRESTRESSSED VOIDED SLABS

405.01 END BLOCKS

End Blocks should be 380 millimeters long withsufficient steel provided to resist the tensile forcesdue to concentrated prestressing loads.

405.02 DIAPHRAGMS

Diaphragms shall be cast within the slab atmidspan for spans up to 12 meters and at thirdpoints for spans over 12 meters.

405.03 LATERAL TIES

One lateral tie shall be provided through eachdiaphragm located at the mid-depth of the section.

405.04 SHEAR KEYS

After shear keys have been filled with anapproved non-shrink mortar, lateral ties shall beplaced and tightened.

405.05 BARRIERS

Barriers shall have a 6 millimeter open joint at themidspan to prevent the barrier from acting as anedge beam and causing long term differentialdeflection of the exterior beam.

406 PRESTRESSED BOX BEAMS

406.01 END BLOCKS

END BLOCKS 450 MILLIMETERS LONGSHALL BE PROVIDED AT EACH ENDAND SUFFICIENT STEEL SHALL BEPROVIDED IN THE END BLOCKS TORESIST THE TENSILE FORCES DUE TOTHE PRESTRESSING LOADS.

406.02 DIAPHRAGM

Diaphragms, cast within the beam, shall beprovided at the midspan for spans up to 15meters, at the third points for spans from 15 to 22meters and at quarter points for spans over 22meters.

406.03 LATERAL TIES

One lateral tie shall be provided through eachdiaphragm located at the mid-depth of the section.However, for the 990 millimeter and 1065millimeter deep sections, when adjacent units aretied in pairs for skewed bridges, in lieu ofcontinuous ties, two ties shall be provided, locatedat the third points of the section depth.

406.04 SHEAR KEYS

After shear keys have been filled with anapproved non-shrink, low slump mortar, lateralties shall be placed and tightened.


Part 3 500-1

SECTION 500 STRUCTURAL STEEL

501 DESIGN CRITERIA

501.01 GENERAL

Structural steel design criteria shall be asspecified in Section 10 of AASHTO except asclarified or modified in this manual.

501.02 DESIGN METHODS

The Service Load Design Method (AllowableStress Design) shall be used except that theStrength Design Method (Load Factor Design)may be used for major or unusual structures whenapproved.

501.03 MATERIALS (AASHTO 10.2)

Materials shall conform with the requirements ofAASHTO Article 10.2 with the selection basedon stress requirements and overall economy.

The preferred maximum thickness of tensionflanges is 50 millimeters. Tension flanges thickerthan 50 millimeters shall be normalized.

501.04 ALLOWABLE FATIGUESTRESS (AASHTO 10.3.1)

Splices, stiffeners, shear connectors and bracingdetails shall be designed using categories Athrough C details in order to limit the fatiguestress.

Category E details shall not be used.

501.05 LOAD CYCLES (AASHTO 10.3.2)

The stress cycle case to be used in AASHTOTable 10.3.2A shall be Case I.

501.06 CHARPY V-NOTCH IMPACTREQUIREMENTS(AASHTO 10.3.3)

Where applicable, the Charpy V-Notch impactrequirements for structural steel shall be forTemperature Zone 1 at elevations less than 1800meters and Temperature Zone 2 at elevations1800 meters and higher, unless otherwise directedby the Project Manager.

Intermediate stiffeners shall be placed only on theinside face of exterior girders.

The number and location of girder shop and fieldsplices shall be determined so as to minimizefabricated and erected cost of the girders.

All connections except field connections shall bewelded. ASTM A325M high strength bolts shallbe used for field connections.


Part 3 600-1

SECTION 600EXPANSION ANDCONTRACTION

601 MOVEMENT CRITERIA

601.01 MOVEMENT RATING

Provisions shall be made in the design ofstructures to resist induced stresses or to providefor movements resulting from variations intemperature and anticipated shortening due tocreep, shrinkage or prestressing. Accommodationof thermal and shortening movements will entailconsideration of deck expansion joints, bearingsystems, restraining devices and the interaction ofthese three items.

The main purpose of the deck joint is to seal thejoint opening to obtain a watertight joint whileallowing for vertical, horizontal and/or rotationalmovement. The bearings are required to transmitthe vertical and lateral loads from thesuperstructure to the substructure units and toallow for movement in the unrestrained directions.Restraining devices are required to limit thedisplacement in the restrained directions.Improper design or construction of any of thesedevices could adversely affect the operation of theother devices.

The required movement rating is equal to the totalanticipated movement (i.e. the difference betweenthe widest and the narrowest opening of a joint).The calculated movements used in determiningthe required movement rating shall be as specifiedin AASHTO except as modified below:

Mean temperature and temperature ranges shallbe as specified in Section 201.08 of this manual.

To allow for the effects of long term creep andshrinkage in precast prestressed concretemembers, the following additional shorteningshall be considered:

Joints: 20 mm per 100 meters.Bearings: 40 mm per 100 meters.

To allow for the effects of long term creep andshrinkage in post-tensioned box girder bridges,the following additional shortening shall beincluded:

Joints: 40 mm per 100 meters.Bearings: 80 mm per 100 meters.

602 DECK JOINTS

602.01 GENERAL

The movement rating for joints for steel structuresshall be based primarily on the thermal expansionand contraction characteristics of thesuperstructure, while for concrete structures theeffects of shortening due to creep and shrinkageand where applicable, prestressing shall also beadded. Movement ratings shall be based ontemperature variations as measured from theassumed mean temperature.

Published movement ratings are usually based onthe difference between the maximum andminimum openings without consideration to therequired minimum installation width. Indetermining the movement rating, considerationmust be given to the installation width required toinstall the seal element.

Other factors which should be considered indetermining the required movement rating includeconsideration of the effects of any skew,anticipated settlement and rotations due to liveloads and dead loads, where appropriate.

Items requiring attention include:

1) The type of anchorage system to be used.2) The method of joint termination at the

ends.3) The method of running joints through

barriers, sidewalks and/or medians.4) Physical limitation on size of joints.5) Susceptibility of joint to leakage.6) Possible interference with post-tensioning

anchorages.7) Selection of appropriate modular

proprietary systems that meet designrequirements.

8) Forces applied to the surroundingconcrete by the joint.


Part 3 600-2

Available types of joints include compressionseals, strip seals, and modular joints.Compression seal joints and strip seal joints aregeneric and should be detailed on the plans, bystandards and/or covered in the specialprovisions. Modular joints are proprietary andrequire that the designer specify allowable jointtypes and styles in the special provisions.Information concerning specific designparameters and installation details of modularjoints should be obtained from literature suppliedby the manufacturer of the system. It is theresponsibility of the designer to review theproprietary joint literature and relatedmanufacturer's specifications to ensure that theselected joint types are properly specified andcompatible with the design requirements.

The following features of joints should be shownon the plans:

1) Blockout details showing a second pour,including blockout dimensions andadditional reinforcing required.

2) Required end treatment in barriers orcurbs, including enough detail orexplanation to accommodate each of theproprietary systems selected (i.e. coverplates, etc.).

3) Consideration to traffic control indetermining section pattern lengths.

4) Movement rating.5) Assumed temperature and opening at time

of installation with temperature correctionfactors.

6) Actual horizontal length of joint measuredfrom inside of barrier face to inside ofbarrier face corrected for skew.

The following features of joints should bespecified in the specifications:

1) For modular joints, the joint style, glandtype, steel edge beam material, and thename of a representative manufacturer.

2) Method of measurement (by linear meterfrom face to face of barrier).

A general discussion of joint types follows.However, for modular joints the actual selectionof the specific alternates should be made from the

list of approved joint types which can be obtainedfrom the Project Manager.

602.02 COMPRESSION SEALS

The compression seal element should have ashape factor of 1:1 (width to height) to minimizeside wall pressure. The size of the compressionseal shall be specified on the plans.

Effective movement ratings for this type of jointrange up to 50 millimeters. Advantages for thistype of joint include its low cost, provenperformance and acceptance for use on pedestrianwalkways. However, this type of joint can not beunbolted and easily raised, generates pressure andis not good for high skews or horizontaldirectional changes.

602.03 STRIP SEALS

Strip seals should generally conform to the detailsshown in the structure detail drawing titled "StripSeal Joint". Proprietary alternates to this detailother than those shown on the detail drawing willnot be allowed.

Effective movement ratings for this type of jointrange up to 100 millimeters. This type of joint isbest used when the movement rating is beyond thecapacity of compression seals and for largeskews. Strip seal joints will require cover platesfor pedestrian walkways.

602.04 MODULAR JOINTS

Modular joints are very complex joint systems.Effective movement ratings range from 100millimeters up to 750 millimeters. Modular jointsare the best choice for movement ratings over 100millimeters.

603 BEARINGS

603.01 GENERAL

Unlike joints, where the opening can be adjustedif the ambient temperature at the time ofconstruction is different than the assumed meantemperature, bearings must be designed to beinstalled at temperatures other than the meantemperature. For this reason, the movement


Part 3 600-3

rating should be based on the full temperaturerange and not the rise or fall from a meantemperature.

Calculation of the movement rating shall includethermal movement and anticipated shortening dueto creep, shrinkage and prestressed shortening.For cast-in-place post-tensioned concrete boxgirder bridges both the elastic and long termprestress shortening effects shall be considered.

An initial offset of the top sliding surface from thecenterline of bearing should be calculated andshown on the plans so that the top sliding surfacewill be centered over the bottom sliding surfaceand the centerline of bearing after all shrinkage,creep and post-tensioning shortening has takenplace in the sperstructure.

Permissible bearing types include neoprene strips,elastomeric bearing pads, steel bearings, slidingelastomeric bearings and high-load multi-rotational bearings (pot, disc or spherical).

Neoprene strips, elastomeric bearing pads andsteel bearings are generic and shall be detailed onthe plans and/or covered in the standardspecifications and special provisions. High-loadmulti-rotational bearings are proprietary bearingtypes and require that the designer include aBearing Schedule in the plans. It is theresponsibility of the designer to review the StoredSpecification to ensure that the bearings areproperly specified and compatible with the designrequirements. Sliding elastomeric bearings areboth generic and proprietary in that a genericbearing should be designed and detailed on theplans with proprietary alternates allowed.

All bearings types except elastomeric bearingpads shall be designed for impact.

603.02 NEOPRENE STRIPS

Neoprene strips consist of a sliding plate on acontinuous neoprene pad. Where appropriate,neoprene strips are the preferred bearing type forpost-tensioned box girder bridges. However,neoprene strips are not appropriate for thefollowing applications: curved bridges, skewsgreater than 20 degrees, contributing spansgreater than 50 meters, where initial shortening

due to prestressing is greater than 25 millimetersand where the movement rating including elasticshortening, long term creep and shrinkage andtemperature is greater than 40 millimeters.

603.03 ELASTOMERIC BEARINGPADS

Elastomeric bearing pads shall conform to therequirements of Section 14 of AASHTO. Bearingpads shall be designed to be constructed usingeither steel or fiberglass laminates, with thecontrolling case determining the size. Thefollowing data should be shown on the plans:

Length, width and thickness of padDurometer HardnessDesign Method (A or B)Design LoadLow Temperature Zone (A, B or C)Elastomer Grade (0, 2 or 3)Shear Modulus

Generally, bearing pads shall be Durometer 60 -Elastormer with steel reinforcement.

Normally Design Method A will be used indesign, however, where only steel reinforced padswill work Design Method B may be used providedthe special testing is performed.

The following should be used as a guide fordetermining low temperature zones:

Elevation (meters) Zone Below 900 A 900-1800 B 1800 and above C

Pads shall have a minimum thickness of 25millimeters and be designated in 10 millimeterincrements. The use of elastomeric bearing padsshould generally be limited to a thickness notgreater than 100 millimeters. Holes will not beallowed in the pads.

Width and length dimensions shall be detailed ineven 50 millimeter increments. When used withprestressed I-girders, pads shall be sized aminimum width of 50 millimeters less than thenominal width of the girder base to accommodatethe 20 millimeter side chamfer and shall be set


Part 3 600-4

back 50 millimeters from the end of the girder toavoid spalling of the girder ends.

Elastomeric pads should not be used in caseswhere deck joints or bearings limit verticalmovements, such as in older style sliding steelplate joints or widenings where existing steelbearings are to remain.

Where elastomeric bearing pads with greasedsliding plates are used on post-tensioned boxgirder bridges to limit the required thickness ofthe pad, the pad thickness should be determinedbased on temperature movements only, with theinitial and long term shortening assumed to betaken by the sliding surface.

Elastomeric bearing pads are the preferredbearing type for new steel girders, precastprestressed girders and post-tensioned box girderbridges where neoprene strips are not appropriate.

603.04 STEEL BEARINGS

Steel bearings may consist of rockers or fixed orexpansion assemblies which conform to therequirements specified in Section 10 ofAASHTO.

Steel bearings are not a preferred bearing typeand their use should normally be limited tosituations where new bearings are to match theexisting bearing type on bridge widening projects.

603.05 SLIDING ELASTOMERICBEARINGS

Sliding elastomeric bearings consist of an uppersteel bearing plate anchored to the superstructure,a stainless steel undersurface and an elastomericpad with a teflon coated upper surface. Theteflon surface shall be attached to a 10 millimeterminimum thick plate which is vulcanized to theelastomeric pad. The bearing accommodateshorizontal movement through the teflon slidingsurface and rotation through the elastomericbearing with the thickness of the elastomericbearing determined by the rotational and frictionforce requirements. Keepers may be used forhorizontal restraint of the pads. Vertical restraintmay be provided by anchor bolts with slottedkeeper plates or individual vertical restrainers as

appropriate. The pad dimensions and all detailsof the anchorage and restraint systems shall beshown on the plans. The special provisionsshould allow for proprietary alternates.

Sliding elastomeric bearings should be consideredfor applications where regular elastomeric bearingpads would exceed 100 millimeters in height orwhere special access details would be required forother proprietary bearings in such places ashinges.

603.06 HIGH-LOAD MULTI-ROTATIONAL BEARINGS

603.06.01 Description

High-load multi-rotational fixed bearings consistof a rotational element of the Pot-type, Disc-typeor Spherical-type. High-load multi-rotationalexpansion bearings consist of a rotational elementof the Pot-type, Disc-type or Spherical-type,sliding surfaces to accommodate translation andguide bars to limit movement in specifieddirections when required.

Pot bearings consist of a rotational elementcomprised of an elastomeric disc totally confinedwithin a steel cylinder. Disc bearings consist of arotational element comprised of a polyetherurethane disc confined by upper and lower steelbearing plates and restricted from horizontalmovement by limiting rings and a shear restrictionmechanism. Spherical bearings consist of arotational element comprised of a sphericalbottom convex plate and mating spherical topconcave plate.

These design criteria were prepared for the broadrange of normal applications and the specifiedlimits of loads, forces and movements. Thedesign and manufacture of multi-rotationalbearings relies heavily on the principles ofengineering mechanics and extensive practicalexperience in bearing design and manufacture.Therefore, in special cases where structuralrequirements fall outside the normal limits, abearing manufacturer should be consulted.


Part 3 600-5

603.06.02 Rotational Requirements

The rotational requirements of these bearings istreated in a new way. Rotational requirements ofthe bearings, Rb, are determined by:

Rb = Rs + Rc

where

Rb = Rotation capacity designed intothe bearing.

Rs = Anticipated rotation of thestructure in service. (includes liveloads and rotations induced byconstruction/erection sequences).

Rc = Rotation induced in the bearingby construction tolerances, 0.02radians maximum (see DesignCriteria 14).

603.06.03 Use

Use of multi-rotational bearings is especiallyindicated where:

1. Low profile, high load bearings arerequired.

2. Long span, curved, or skewed bridges

and other similar structures of complexdesign are required.

3. Long slender columns or light frames

and members exhibit minimum stiffnessor rigidity.

4. The direction of rotation varies. 5. The direction of rotation cannot be

precisely determined. 6. Settlement of the substructure is

anticipated. 7. Self aligning capabilities are required. 8. Load and rotation eccentricity does not

significantly alter the net distribution ofstress through the bearing and into thesubstructure and superstructure.

9. It is desirable to reduce the momentapplied to truss or space frame panels.

10. Large movements are anticipated. 11. Economical, long life, or low

maintenance bearings are desirable. 12. Regular elastomeric bearing pads

would exceed 100 millimeters in height.

603.06.04 Design Criteria

Since special details are required to allow foraccess for inspection, repair or replacement of thebearings, the respacing of joints to eliminate theneed for use of these bearing types should beconsidered.

Some structural considerations in use of multi-rotational bearings are listed below. Reference to"this specification" refers to the design criteriabelow.

1. Vertical and horizontal loads shall beassumed to occur simultaneously. Allloads are service loads. Minimumvertical loads are for dead loads andsuperimposed dead loads excluding thefuture wearing surface. Maximumvertical loads are for dead loads,superimposed dead loads including thefuture wearing surface, and live loadsand impact.

2. The total recommended clearance

between all guiding and guided slidingsurfaces is 1.5 millimeters in order tolimit edge stress on guiding interfaces.

3. Avoid specifying total spacing of more

than 1.5 millimeters between guidesand guided components where possible.

4. In specifying the horizontal force

capacity of bearings, it is recommendedonly one fixed or guided expansionbearing shall be assumed to resist thesum of all the horizontal forces at eachabutment, bent, column, hinge or pier.


Part 3 600-6

5. Where feasible provide at least twofixed or guided expansion bearingseach able to resist all horizontal forcesat each abutment, column, hinge or pierfor design redundancy.

6. Some press-fit guide bar details in

common use have provenunsatisfactory in resisting horizontalloads. When analyzing these designs,consideration should be given to thepossibility of rolling of the bar in therecess.

7. Multi-rotational bearings should not be

used at vertical loads less than 20% oftheir vertical capacity. Bearings forless than 20% vertical capacity requirespecial design.

8. Special consideration in bearing design

shall be given where high horizontal tovertical load (above 0.30) isanticipated.

9. Frictional resistance of bearing slide

surfaces should be neglected whencalculating horizontal load capacity.

10. The installed alignment of bearing

guiding systems relative to theanticipated movement direction of thestructure should be carefully consideredto avoid bearing guide system failure.Special studies or designs may berequired on curved or skewedstructures to ensure correct installation.

11. The substructure and superstructure

should be designed so as to remainrigid under all service conditions inareas around and in contact with thebearings, paying particular attention tothe use of stiffeners at extreme pointsof movements.

12. The substructure and superstructuredesign should permit bearings to beremoved for inspection or rehabilitationby minimum jacking of the structure.Jacking points shall be provided in thestructural design.

13. The minimum Structure Rotational, Rs,

of bearings covered in the specificationis 0.01 radians. Rs comprises liveloads and rotations induced byconstruction/erection sequences.

14. The maximum Construction Rotation,

Rc (rotation induced by constructiontolerances), is 0.02 radians. Thedesigner may elect to specify a smallerRc than 0.02 radians but is cautionedto investigate the cost and practicalityof the changes contemplated.

15. Recommended coefficients of friction

for structure design follows:

Unfilled sheet or woven fiberPTFE/stainless steel 0.04

Filled PTFE sheet/stainless 0.08

The above coefficients of friction arebased on the average stress and limitsof edge stress of PTFE in thisspecification. Out of level installationswithin the limits of this specificationand normal in service oxidation of thestainless steel mating surface. Serviceconditions, where exceptional corrosionof the stainless steel mating surfacemay occur, will require specialassessment of the long term coefficientof friction.

16. Pot, disc and spherical multi-rotationalbearings should not be mixed at thesame expansion joint or bent. Thediffering deflection characteristics anddiffering rotation characteristics mayresult in damage to the bearings and/orstructure.

17. Contract drawings and documents

should contain a Bearing Schedule (SeeSection 603.07, Bearing Schedule).

18. Some bearing tests are very costly toperform. Other bearing tests cannot beperformed because of the unavailabilityof test equipment. The following test


Part 3 600-7

requirements should be carefullyconsidered before specifying them:

A) Vertical loads exceeding2,250,000 kg.

B) Horizontal loads exceeding

225,000 kg. C) The simultaneous application

of horizontal and vertical loadswhere the horizontal loadsexceeds 75% of the verticalloads.

D) Triaxial test loading. E) The requirement for dynamic

rotation of the test bearingwhile under vertical load.

603.07 BEARING SCHEDULE

A bearing schedule shall be included in thecontract drawings and documents and shallcontain the following as a minimum:

1. A schedule of all minimum andmaximum vertical and horizontalservice loads.

2. Minimum Structure and Construction

Rotation requirements. 3. Magnitude and direction of movements

at all bearing support points. 4. Quantity, type (fixed, expansion or

guided expansion). 5. Plan view, alignment and location of all

bearing units. 6. Allowable upper and lower bearing

contact pressure. 7. Fixing or anchorage details and/or

requirements. 8. Grades, bevels and slopes of all

bearings.

9. Allowable coefficient of friction ofslide surfaces.

10. Surface coating requirements and the

appropriate specifications. 11. Seismic requirements, if any. 12. Uplift details, temporary attachments

or other requirements. 13. Installation scheme. 14. Bearing preset details, if required.

Design rotation, movement and otherrequirements in the Bearing Schedule should onlyrefer to the requirements of the structure wherethe bearings are to be used.

604 RESTRAINING DEVICES

604.01 GENERAL

Restraining devices are meant to prohibitmovement in a specified direction. Restrainingdevices shall be designed to resist the imposedloads including earthquake as specified inAASHTO and as modified in Section 200 of thismanual.

Restraining devices could include concrete shearkeys or end blocks, horizontal or vertical cablerestrainers or mechanical restraining deviceswhich could be an integral part of a bearing or aseparate system. Restraining devices to prohibitvertical displacement at expansion ends, shall bedesigned to allow for inspection and futurereplacement of bearings.

Allowable restraining devices include, but are notlimited to the following: Vertical FixedRestrainers, Vertical Expansion Restrainers,External Shear Keys, Internal Shear Keys andKeyed Hinges.

604.02 VERTICAL FIXEDRESTRAINERS

Vertical fixed restrainers consist of cable andappropriate hardware and are designed to allow


Part 3 600-8

rotation but no translation in either horizontal orvertical directions.

604.03 VERTICAL EXPANSIONRESTRAINERS

Vertical expansion restrainers consist of cableand appropriate hardware and are designed toallow rotation and longitudinal translation but notransverse translation. Some limited verticaldisplacement is allowed to permit replacement ofbearings if required.

604.04 EXTERNAL SHEAR KEYS

External shear keys are reinforced concrete blocksdesigned to limit transverse displacement whileallowing longitudinal and rotational movements.External shear keys are preferred to internal shearkeys since they are more accessible for repairsand easier to construct.

604.05 INTERNAL SHEAR KEYS

Internal shear keys are reinforced concrete blocksdesigned to limit transverse displacement whileallowing longitudinal and rotational movements.

604.06 KEYED HINGE

A keyed hinge is a restraining device which limitsdisplacements in both horizontal directions whileallowing rotation.

For a typical expansion seat abutment whererestraining devices are required, the restrainingdevices will consist of vertical expansionrestrainers and external shear keys.

For a typical pinned seat abutment for a post-tensioned box girder bridge, restraining deviceswill consist of vertical fixed restrainers andexternal shear keys. For a typical pinned seatabutment for a prestressed girder bridge,restraining devices will consist of vertical fixedrestrainers and external or internal shear keys.

For a typical expansion pier, restraining deviceswill consist of vertical expansion restrainers andinternal shear keys.

For a typical pinned pier, restraining devices willconsist of vertical fixed restrainers and internalshear keys or a keyed hinge.


Part 3 700-1

SECTION 700GEOTECHNICAL

701 FOUNDATIONS

701.01 GENERAL

The main purpose of this section is to documentbridge design criteria as related to bridgefoundation geotechnical issues.

Since problems requiring geotechnical andstructural expertise often result in confusionconcerning the responsibilities of each, anotherpurpose of this section is to define the role of thegeotechnical engineer and the bridge engineer indesign problems involving both fields.

The usual procedure for designing bridgefoundation substructure units is as follows:

The bridge design group will develop apreliminary location plan.

The Geotechnical Engineer will conduct a siteinvestigation, identify borehole locations, drill andlog borings, perform soil testing as appropriate,plot the boring logs and summarize the results ina Geotechnical Report. The Geotechnical Reportwill include a Foundation Design Report whichidentifies the type of foundation recommended foreach substructure unit including the allowableloads and required depths.

The Geotechnical Engineer is responsible forpreparing the boring logs on construction plans.They also prepare necessary special provisionsfor construction of the foundation elements.During construction of the bridge foundations, theGeotechnical Engineer oversees geotechnicaltesting, spread footing excavations and piling anddrilled shaft construction. They work closelywith bridge design group to jointly resolveproblems requiring redesign because of changedsite conditions. The bridge design group isresponsible for producing the structural designand construction documents for the substructureunits as part of the bridge plans.

701.02 SPREAD FOOTINGS

Where good soil materials exist near the surface,shallow foundations in the form of spreadfootings will normally be the recommendedfoundation type. For foundation units situated ina stream, spread footings shall only be used whenthey can be placed on non-erodible rock. Spreadfootings are normally not placed on embankmentmaterial.

When spread footings are the recommendedfoundation type, the Geotechnical Report shallcontain the allowable bearing pressure, theelevation of the bottom of the footing and theestimated total settlement, differential settlementand time rate of settlement, if applicable.

The bridge design group shall size the footing toensure that the allowable bearing pressure is notexceeded for any AASHTO Group Loading andthat the footing is properly sized and reinforced toresist the maximum applied moments and shears.The bottom elevations of spread footings shall beset at the recommended depth. The minimum topcover over the top of footings shall be 500millimeters. If the possibility for differentialsettlement is identified, the bridge designer shallensure that the entire structure is capable ofstructurally resisting the forces induced by thedifferential settlement.

701.03 PILE FOUNDATIONS

When good foundation material is not locatednear the surface, when settlement is a problem, orfor foundation units located in streams wherescour is a problem, deep foundations will usuallybe recommended. One type of deep foundation isa driven pile. Driven piles may be either steel Hpiles, steel pipe piles or prestressed concrete piles.The other type of deep foundation is a bored pile.


Part 3 700-2

701.04 DRIVEN PILES

The Geotechnical Engineer is responsible forrecommending when driven piles are to be used,The type of driven pile to be used, the allowablecapacity of the pile, the estimated pile tipelevation and any special requirements necessaryto drive the piles. When steel piles are used, thecorrosive life of the pile will be reported in theGeotechnical Report. The Geotechnical Engineeris also responsible for running the WEAP87 waveequation computer program to determine thedriveability of the specified piles and to developcharts or other guidelines to be used byconstruction personnel to control the pile drivingprocess.

The bridge design group is responsible forensuring that the allowable axial capacity is notexceeded for any AASHTO Group Loading andthat the pile can withstand the applied lateralloads.

701.05 BORED PILES

A bored pile foundation consists of excavating around hole by machine, installing a metal casingor liner, placing a reinforcing cage in the casingor liner and then filling the casing or liner withconcrete.

The Geotechnical Engineer is responsible forrecommending the minimum diameter of boredpile to be used and providing the necessaryinformation for determining the minimumrequired embedment below a specified elevationto develop the required axial load. TheGeotechnical Engineer is also responsible fordetermining the soil properties in each layer to beused in analyzing lateral loads and whether slurrymethods of construction may be utilized. Ifnecessary, methods of testing the pile afterconcreting will be specified in the GeotechnicalReport.

For the most part, bored piles will include atemporary casing or liner intended to preclude theintrusion of earth into the hole during the boringoperation and a permanent casing or liner thatwill remain in place and not be withdrawn duringthe concreting process. The temporary casingwill be advanced a sufficient depth into rock toprovide a seal against water inflow. Thetemporary casing shall be clean and free of waterbefore the permanent casings or liners, reinforcingsteel and concrete are placed.

The bridge design group is responsible forensuring that the allowable axial capacity is notexceeded for any AASHTO Group Loading andthat the shaft can withstand the applied lateralloads.

Unless specified otherwise in the GeotechnicalReport, the following minimum criteria should beused in designing bored pile foundations:

1. Bored Piles shall be spaced a minimum oftwo diameters measured center to center ofthe holes plus 100mm.

2. Temporary and permanent casings or liners

shall be designed to withstand handlingstresses, applicable concrete and surroundingsoil pressures, and shall be watertight.

3. Vertical reinforcing should be detailed to

provide the minimum recommended clearancein AASHTO Article 4.6.6.2.1. In no caseshall the clearance between verticalreinforcing be less than 115 millimeters.

4. Reinforcement shall have a clear distance of

not less than 50 millimeters from the insideface of the permanent casing or lining.

5. Horizontal ties should be spaced at 150

millimeters minimum. 6. The footing, if applicable, shall be sized to

extend a minimum of 200 millimeters fromthe edge of a bored pile.


Part 3 800-1

SECTION 800RETAINING WALLS

801 DESIGN CRITERIA

801.01 GENERAL

Retaining walls are used when normal fill or cutslopes extend beyond acceptable limits. Wallsmay be classified in the following classes:

Gravity Walls• Bin• Crib• Wire basket• Mass concrete

Cantilever Walls• Concrete

Braced Walls• Anchored Walls• Soldier pile and lagging• Tangent cylinder piles

Mechanically Stabilized Walls• Reinforced Earth• VSL Retained Earth• Hilfiker-Reinforced Soil embankment

Walls shall be designed for a minimum factor ofsafety of 1.5 against sliding and 2.0 againstoverturning.

The wall selection process includes identificationof types of walls appropriate for the site,evaluation of geotechnical behavior andproperties affecting wall behavior and selection ofwall systems which fit all site constraints.Identification of alternate designs may beappropriate.

In determining the types of retaining wallscapable of fitting a particular site the followingshould be considered:

• Availability of materials• Service life, maintenance, future use• Deflection tolerance• Ease of construction• Environmental/visual considerations• Special loading requirements• Settlement tolerance• Availability of space

801.02 POLICY

The following policy shall apply to retaining walldesign:

1. Walls up to 6 meters high:

The Consultant shall preparedrawings for cast-in-place concreteretaining walls utilizing the AbuDhabi Roads Section Standards andSpecifications.

2. Walls over 6 meters high:

The Consultant shall evaluate theapplicability of mechanicallystabilized wall systems and confirmtheir site-specific suitability. If theConsultant determines that amechanically stabilized wall systemis not appropriate due to soilsconditions or other site specificconditions, a complete cast-in-placeconcrete retaining wall design mustbe prepared for inclusion into the biddocuments.

801.03 RESPONSIBILITIES

The design of a retaining wall will usually involvethe efforts of three sections: Roadway DesignSection, Geotechnical Section, and the BridgeDesign Section.

801.03.01 Roadway Design Section

Roadway Design Section is responsible foridentifying the need for and limits of the retainingwalls. They will be responsible for providing aprofile adjacent to the top of the wall and the soilprofile line along the front face of the wall.Roadway Design is also responsible foridentifying the acceptable limit of excavationrequired to maintain traffic and to design anydetours when required.


Part 3 800-2

801.03.02 Geotechnical Section

The Geotechnical Section is responsible forinvestigating the site, drilling exploratory holes asrequired, determining the external stability of thesite and determining the material properties of theexisting soil and backfill. The GeotechnicalSection will also recommend soil strengthparameters and groundwater elevations forcomputing design lateral earth pressure. They arealso responsible for determining the maximumsafe slopes allowed during excavation.

The Geotechnical Section also is responsible fordetermining the type of foundation required tosupport the wall loads, the allowable bearingpressure of the soil and the minimum requireddepths of the foundation units. This Sectiondetermines the soil properties to be used indetermining the lateral loads to be applied to thewall and determines the amount of settlement,differential settlement and the time rate ofsettlement for walls on compressible foundationsoils.

The Geotechnical Section prepares appropriateSpecial Provisions for construction of theretaining walls and monitors construction of thefoundation elements, assisting the residentengineer as requested concerning geotechnicalissues. The Section works closely with the BridgeDesign Section on any structural design changesneeded during construction because of changedsite conditions.

801.03.03 Bridge Design Section

The Bridge Design Section is responsible for thedesign of the structural elements of the wall, thelength of the wall and for producing the requiredconstruction plans, when requested by others, forany non-proprietary wall requiring structuralanalysis. The Bridge Design Section is alsoresponsible for determining whether shoring willbe required during construction based on theacceptable limits of excavation provided byRoadway Design and the safe excavation slopesprovided by Geotechnical. The Bridge DesignSection also selects walls which will handledifferential settlement, when present, and provides

details for drainage on plans. Appurtenant trafficand/or pedestrian rails will also be designed anddetailed by the Bridge Design Section. ThisSection works with the Geotechnical Section onrequired structural design changes duringconstruction because of changed site conditions.

801.04 PROPRIETARY RETAININGWALLS

When a proprietary retaining wall is chosen as anacceptable alternate, the special provisions willspecify the pre-approved wall systems which areacceptable for the particular application and site.The proprietary wall type is to be chosen from apre-approved list of wall types. The contractorwill be required to identify the alternate in his bid,with bid shopping after the award of the contractnot allowed.

The Roadway Design Section will prepare plansshowing the location and extent of the walls andthe profile along the top of the wall and the soilprofile along the front face of the wall. The plansshould also show any restrictions regardingexcavation which may exist and requirements forappurtenant features such as traffic barrier,handrail or other attachments. Blockouts forlighting, signing, utilities and drainage structureswill also be detailed on the plans or identified tobe included with the proprietary plan submittals.

The Geotechnical Section will prepare specialprovisions containing the design criteria to beused in evaluating the proprietary wall. As aminimum the following should be included:

1. The minimum factor of safety againstoverturning

2. The minimum factor of safety against sliding3. Maximum coefficient of friction against

sliding4. Phi angle of the backfill5. Allowable bearing pressure6. Minimum design life7. Water table level8. Elevation of footing bottom9. Maximum tolerable deflection


Part 3 900-1

SECTION 900MISCELLANEOUS

901 TRAFFIC STRUCTURALSUPPORTS

901.01 GENERAL

Luminaires, traffic signals and sign supportsshall be designed using the AASHTOSpecifications for Structural Supports except asclarified or modified in this manual.

901.02 WIND SPEED

Major structural supports shall be designed forthe wind frequency of 160 kph.

901.03 ALLOWABLE STRESSES

The, L /45.7 limitation on dead load deflectioncontained in Article 1.9.1(A) need not besatisfied since there is no scientific basis tosupport this limitation.

For high mast light poles, the maximumdeflection shall be limited to 15% of the poleheight under wind load. The maximum allowableyield strength for design purposes shall be 4590kg/cm2.

For all other applications, for steel with a yieldstrength greater than 3360 kg/cm2, the allowablestresses for design shall be limited to a yieldstrength of 3360 kg/cm2. This limitationindirectly places a limit on allowable deflectionsin an attempt to satisfy the criteria of Article1.9.1. This limitation also reduces the stresses inany high strength welds which are more brittleand subject to cracking due to fatigue fromvibrations.

902 UTILITIES IN STRUCTURES

902.01 GENERAL

Where utility conflicts exist; water, power,telephone, cable TV and gas lines will berelocated as required for construction of theproject. Where it is feasible and reasonable tolocate utility lines elsewhere, attachment to

structures will not be permitted. Trenching in thevicinity of existing piers or abutments shall bekept a sufficient distance from footings toprevent undercutting of existing footings or toprevent disturbing foundation soils for futurefoundations.

Where other locations prove to be extremelydifficult and very costly, utility lines exceptnatural gas may be allowed in the structures.

Natural gas encroachments will be evaluatedunder the following policy:

A. Cases where gas line attachments tostructures will not be considered under anycondition:

1. Grade separation structures carryingvehicular traffic on or over freeways.

2. Inside closed cell-type box girderbridges.

3. High pressure transmission lines over 4kg/cm2 and/or distribution lines of over150 millimeters in diameter.

4. Gas lines over minor waterway crossingswhere burial is feasible.

B. Gas line attachments on structures will beconsidered under the following cases orconditions:

1. Each case will be judged on its ownmerit with the utilities providingcomplete justification as to whyalternative locations are not feasible.

2. Economics will not be a significantfactor considered in the feasibility issue.

3. Open girder type structures across majorrivers.

4. Pedestrian or utility bridges whereproper vented casings and other safetysystems are used.

5. All lines are protected by casements.

Provision for accommodation of relocated andfuture utilities on structures should follow thefollowing General Policy.


Part 3 900-2

902.02 POLICY

Support bracket details and attachments for allutilities will require Bridge Group approval.

All approved utilities shall have individualsleeved casings, conduits or ducts as appropriate.

All utilities carrying liquids shall be placed insidecasings through the entire length of the structure.The casing shall be designed to carry full servicepressure so as to provide a satisfactorycontainment in case the utility is damaged orleaks.

Water lines, telephone conduits, power lines,cable TV lines, supports or other related itemswill not be permitted to be suspended below orattached to the exterior of any new or existingstructure.

Product lines for transmitting volatile fluids willnot be permitted to be attached to or suspendedfrom or placed within any new or existingstructure.

902.03 UTILITY AGENCYRESPONSIBILITY

The utility agency is responsible for obtainingnecessary information regarding the proposedconstruction schedule for the project. Theagency shall submit a request includingjustification for attaching to the structure andpreliminary relocation plans including line massand support spacing as early as possible but nolater than the completion of preliminarystructural plans.

The utility agency shall be responsible for thedesign of all conduits, pipes, sleeves, casings,expansion devices, supports and other relateditems including the following information:

1. Number and size of conduits for power,telephone and cable TV lines.

2. Size and schedule of carrier pipe forwater lines.

3. Size and schedule of sleeved casings.4. Spacing and details of support brackets.5. Expansion device details.6. Total combined weight of carrier pipe

and transmitted fluids, conduits, casings,support brackets, expansion joints andother related items.

7. Design calculations.

902.04 BRIDGE GROUPRESPONSIBILITY

The Bridge Group shall be responsible for andhave final approval authority for the followingaspects of the design:

1. Determination of how many lines, if any,the structure can accommodate.

2. Determination of where such lines shouldbe located within a structure.

3. Determination of the size of the accessopenings and design of the requiredreinforcing.

4. Determination of construction problemsrelated to required sequencing of project.

5. Tracking man-hours associated withutility relocations for cost recovery.

Usually utilities will be accommodated byproviding individual access openings for casingsand sleeves to pass through. Access openingsshould be 50 millimeters larger than the diameterof the casings or sleeves and spaced as requiredby structural considerations.

For box girder bridges, access openings shouldbe located as low as possible but no lower than250 millimeters above the top of the bottom slabto allow for support brackets to be supportedfrom the bottom slab. Where possible all utilitiesshall be supported from the bottom slab for boxgirder bridges.

For girder bridges, the utilities shall not beplaced in the exterior girder bay and shall besupported from the deck slab.


Part 3 900-3

903 FALSEWORK POLICY FORBRIDGE CONSTRUCTION

903.01 FALSEWORK REQUIREMENTS

To ensure that traffic handling is given properconsideration in the early design stages, it isnecessary to identify traffic handling andfalsework assumptions in the Bridge SelectionReport. If falsework is to be used, the horizontaland vertical clearances shall be shown on theGeneral Plan. Usually, one of the followinglisted conditions will prevail:

1. Traffic will be routed around constructionsite.

2. Traffic will pass through construction site.

A. No falsework allowed over traffic. Thisrestriction would require precastconcrete or steel superstructure with fieldsplices located clear of traffic.

B. Stage construction required. Stageconstruction must be detailed on theplans. Construction joints or hingeswould be required.

C. Falsework openings required. The sizeand number of openings must be shown.

General discussions and a table of falseworkopenings are covered under "FalseworkClearances".

903.02 FALSEWORK USE

When traffic must pass through the constructionsite, three possible conditions exist. Condition2.A. is limited to sites which can be spanned byprecast members or where steel is competitive incost. The staged construction option ofCondition 2.B. is not always feasible while thepresence of a hinge is a permanent disadvantage.Condition 2.C. is used for all other cases when itis necessary to route traffic through theconstruction site. The elimination of permanentobstructions by using longer spans andeliminating shoulder piers will usually outweighobjections to the temporary inconvenience offalsework during construction.

903.03 FALSEWORK CLEARANCES

For cast-in-place structures, the preferred methodof construction is to route traffic around theconstruction site and to use earth fills forfalsework. This provides an economical solution,a safe working area and eliminates possibleproblems associated with the design, approval,construction and performance of falseworkincluding the possible effect of excessivedeflections of falsework on the structure.

When the street or highway must be kept openand detours are not feasible, falsework shall beused with openings through which traffic maypass. Because the width of traffic openingsthrough falsework can significantly affect costs,special care should be given to minimizingopening widths consistent with traffic and safetyconsiderations. The following should beconsidered:

1. Staging and traffic handlingrequirements.

2. The width of approach roadway that willexist at the time the bridge isconstructed.

3. Traffic volumes and percentage oftrucks.

4. Vehicular design speed.5. Desires of local agencies.6. Controls in the form of existing facilities.7. The practical problems of falsework

construction.8. Consideration of pedestrian

requirements.

The minimum width of traffic openings throughfalsework for various lane and shoulderrequirements shall be as shown in Table 900.01.The resulting falsework span shown in Table900.01 is the minimum span. When temporaryconcrete barrier is used, 0.6 meters of safetymargin per side is allowed for deflection. Whenblocked-out "W" beam is used, 1.2 meters ofsafety margin per side is allowed for deflection.The normal spans may be reduced or increased ifother forms of protection are used depending onthe required space for installation and deflection.The actual width of traffic openings throughfalsework and the resulting falsework span to beused in design shall be determined by the Abu


Part 3 900-4

Dhabi Roads Section Project Manager and shallbe stated in the Bridge Selection Report.

To establish the grade line of a structurespanning an existing street or highway,allowance must be made for depth of falsework,where used, to provide the clearance needed topermit traffic through the work area duringconstruction. The minimum allowances to bemade for depth of falsework shall be as shown inTable 900.02 and shall be based on the actualfalsework openings determined by the Abu DhabiRoads Section Project Manager.

The minimum vertical clearance for falseworkover freeways shall be 4.50 meters.

Where the vertical falsework clearance is lessthan 4.50 meters, advance warning devices shallbe specified or shown on the plans. Such devicesmay consist of flashing lights, overhead signs,over-height detectors or a combination of these orother devices. A standard insert sheet has beendeveloped for the details of the over-heightdetectors or safety beams. Providing for thesedevices in the specifications or on the plans shallbe the responsibility of the Abu Dhabi RoadsSection Project Manager.

Note to bridge designer: Special considerationshall be given to limit the maximum allowabletension in a precompressed tensile zone of post-tensioned box girder bridges supported onfalsework with large openings.

Table 900.01FALSEWORK SPAN REQUIREMENTS

Detour Roadway Minimum Width Resulting Falsework Span (1)Facility to No. Shoulder of Traffic Temporary Blocked-outbe spanned Lanes Widths Opening (1) Conc. Barrier "W" beam

(meters) (meters) (meters) (meters)Freeway & 1 0.6 & 0.6 4.8 7.2 8.4Non-Freeway 2 0.6 & 0.6 8.4 10.8 12.0

3 0.6 & 0.6 12.0 14.4 15.6 4 0.6 & 0.6 15.6 18.0 19.2

NOTES: (1) Traffic Opening and Falsework Span are measured normal to detour centerline.

Table 900.02FALSEWORK DEPTH REQUIREMENTS

Falsework Opening 7.2 8.4 10.8 12.0 14.4 15.6 18.0 19.2 (meters)Minimum RequiredFalsework Depth(mm)Max 3365 kg/m 485 510 585 815 915 1070 1095 1145per girder line3365 - 4580 kg/m 510 560 815 890 1070 1120 1145 1170per girder line

NOTES:1. DL based on 2550 kg/m3 concrete.2. Table 900.02 is based on the superstructure concrete being designed for zero tensile stress at the

falsework openings. Superstructures designed with concrete tensile stresses can significantlyincrease the required falsework depths shown in the table and amount of falsework required.

3. Structures with greater than 4580 kg/m Dead Load per girder line will require specialconsiderations for required falsework depths.


Part 3 900-5

904 CONSTRUCTION JOINTGUIDELINES FOR BRIDGECONSTRUCTION

904.01 GENERAL

The type of structure and method of construction,combined with sound engineering judgment,should be used in determining the number andlocation of superstructure construction joints.The use of construction joints should beminimized for ease of construction andsubsequent cost savings. Some items whichshould be considered are:

1. Method of construction - earthen fillfalsework, conventional falsework orgirder bridge without falsework.

2. Phase construction because of physicalconstraints such as traffic handling.

3. Span length and estimated rotation anddeflection.

4. Degree of fixity at abutments and piers.5. Effects of locating a construction joint in

a region of negative moment.6. Volume of concrete to be poured without

a joint.7. Consequences of continuous pour,

including adverse effects caused by abreakdown during the pour.

Some important requirements regardingconstruction joints contained in the StandardSpecifications are as follows:

1. The sequence of concrete placementshall be as shown on the project plansor as approved by the Engineer whennot shown on the project plans.

2. The rate of concrete placement andconsolidation shall be such that theformation of cold joints withinmonolithic sections of any structure willnot occur.

3. The rate of concrete placement formajor structures shall not be less than27 cubic meters per hour unlessotherwise specified or approved inwriting by the Engineer.

4. Placement of the deck concrete shall bein accordance with the placing sequenceshown on the project plans.

5. The Contractor shall submit drawingsshowing the placement sequence,construction joint locations, directionsof the concrete placement and any otherpertinent data to the Engineer for hisreview. The drawing shall be submittedat least four weeks prior to the date ofdeck placement.

6. Construction joints shall be placed inthe locations shown on the project plansor as approved by the Engineer.

7. All construction joints shall beperpendicular to the principal lines ofstress and in general located at points ofminimum shear and moment.

904.02 LONGITUDINALCONSTRUCTION JOINTS

Longitudinal construction joints in bridge decksand/or superstructures should be identified asoptional unless required by construction phasing.The optional deck joints should be placed on lanelines or at center of structure. All longitudinalconstruction joints should be keyed.

904.03 PRECAST CONCRETE GIRDERBRIDGES

Precast concrete girder bridges made continuousover supports shall have transverse constructionjoints placed so that the girders undergo theirpositive moment deflections prior to the finalpour over the negative moment areas of the fixedpiers or abutments. There shall be no horizontalconstruction joint between fixed pier diaphragmor abutment diaphragm and the deck.

Girder bridges will usually require details on theplans showing a plan view with joint locations,deck pour sequence and direction of pour, ifrequired. There should be a minimum of 12hours between adjacent pours. A continuouspour from abutment to abutment will not beallowed. Construction joints where requiredshould be parallel to the centerline of the pier.Their location will be near the point of minimumdead load plus live load moment and shear. Thisdistance is generally one-quarter of the spanlength from the pier if the adjacent spans areapproximately equal length.


Part 3 900-6

904.04 STEEL GIRDER BRIDGES

The effects of uplift and allowing a continuouspour should be considered when developing deckpour schedules for multi-span continuous steelgirder bridges. The required rate of pour shouldbe compared to the quantity of concrete to beplaced and the potential for poured sections to setup and develop tensile stresses from pours inadjacent spans shall be considered whendetermining the need for construction joints.Consideration must be given to the potential fornegative moment stresses in the deck due toplacement of positive moment pours in adjacentspans.

Girder bridges will usually require details on theplans showing a plan view with joint locations,deck pour sequence and direction of pour, ifrequired. Except where otherwise required, thereshould be a minimum of 12 hours betweenadjacent pours. Construction joints, whererequired, should be parallel to the centerline of

the pier. Their location should be near the pointof dead load counterflexure.

904.05 CAST-IN-PLACE BOX GIRDERBRIDGES

Box girder bridges made continuous oversupports shall have transverse construction jointsplaced so that the webs undergo their positivemoment falsework deflections prior to the finalpour over the negative moment areas of the fixedpiers or abutments if the superstructureformwork is supported on conventionalfalsework. The transverse construction jointsmay be omitted if the superstructure formwork issupported on earthen fill. The webs and alldiaphragms should be poured concurrently withthe bottom slab. Transverse construction jointswhere required should be parallel to thecenterline of the pier. Their location near theinflection point is generally one-quarter of thespan length from the pier if the adjacent spansare approximately equal length.