highway design standard (cnr 32-01-07)

8/4/2019 Highway Design Standard (CNR 32-01-07)

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CONSTRUCTION NORMS AND REGULATIONS

HIGHWAY DESIGN STANDARD

CNR 32-01-07

Second official edition

MINISTRY OF ROAD, TRANSPORT AND TOURISM

Ulaanbaatar

2007


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1 GENERAL PROVISIONS

Highway classification

Functional classification

Technical classification

General design principles

Design vehicle dimensions

2. HIGHWAY OPERATIONS AND TRAFFIC SAFETY

General principles

Roadway lighting

3 ENVIRONMENTAL PROTECTION

Environmental impact assessment

4 BASIC DESIGN CONTROLS AND REQUIREMENTS

Design speed and loads

Cross Section Elements

Number of Traffic Lanes

Lane width

Auxiliary lanes

Cross slopes

Travelway widening

Horizontal and Vertical alignment

Landscape Design

Bicycle paths and sidewalks

5 INTERSECTIONS AND JUNCTIONS

At grade intersections and junctionsInterchanges

Intersection; highways with railroads and utility lines

6 ROADBED

General

Design groundwater level

Soils

Aclive subgrade layer

Embankments

Cuts

Drainage facilities

Roadbed in difficult conditions

7 PAVEMENT STRUCTURE

Pavement classification

Performance requirements for pavement surfacing


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General Design Principles

Rigid pavements

Additional pavement layers

8 BRIDGES, CULVERTS AND TUNNELS

9 HIGHWAY HARDWARE AND PROTECTION STRUCTRES

Roadside and traffic safety

Traffic barriers

Median barriers

Guide posts

Road signs and markings

Protection structures

10 ROAD SERVICE FACILITIES

Service centers

Rest areas

Fueling stations

Border crossing facilities

APPENDIX A

Glossary

APPENDIX B

Design width of clear roadside zone

APPENDIX C

Climatic factors and Geotechnical properties of soils


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HIGHWAY DESIGN STANDARD

Highway design standards in this document govern design of new and reconstruction ofexisting public roads outside of urban areas, irrespective of their state or private ownership.

The present standard does not apply to design of temporary public roads.

1. GENERAL PROVISIONS

1.1 Design according to the present standards are based on a functional roadclassification system whereby the characteristics of a highway are determinedbased on its functional purpose and related level-of service requirements.

1.2 Level-of-service is a qualitative index reflecting general operating conditionswithin a traffic stream defining safety, comfort, lack of traffic interruptions anddetermined primarily by the congestion level reflected in the service flow volumeto capacity ratio.

1.3 General quantitative characteristics of six levels of service, from A to F, are givenin Table 1 with quantitative criteria based on peak hour traffic volume to highway

capacity ratio.1.4 Design criteria specified in terms of the required level of service should be

satisfied for Design Hourly6 Volume defined as hourly traffic volume that can beexceeded during not more than 50 hours of the last year of design period.

1.5 In instances when data on hourly traffic volumes are not available it is permissibleto use two-way Annual Average Daily Traffic for design of facilities classified as aconventional highway in Par 1.8.

In conditions when the average monthly daily traffic for the peak volume monthmore than twice exceeds the average annual daily traffic, the later should beincreased by a factor of 1.5 for design purposes.

Classification of Highway1.6 The road classification system used in this standard:

Subdivides road into functional classes on the basis of common traffic andland services within the transportation network and, as a rule, administered bythe same jurisdiction.

identifies highway types based on technical characteristics selected toperform specific network functions.

subdivides roads within the same type into technical categories based ontraffic volumes.


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Table 1

Levels of Traffic Passage (levels of Service criteria)

Level-of-Service

Volume to capacityratio

Traffic volume perlane per hour

Traffic characterization

Two-laneMulti-lane Two-lane

Multi-lane Two-lane Multi-lane

A

Highestlevel

< 0.10

All terraintypes

< 0.30 < 150


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highways with restricted access, whereaccess connections are by meansof grade-separated interchanges with a limited number of selected publicroads

highways with partially restricted access, achieved either by means of grade-separation structures or through at-grade intersections such that preference is

given to through traffic. Grade-separated railway crossings are mandatory aspartial access control.

conventional highways, with no restrictions on access in most cases.

1.9 For purposes of selecting effective design solutions to assure performance ofroadfunctions according to classification in Par.1.7, public roads are subdividedinto the following four design types:

Expressways: accommodate movements of traffic volumes safe, comfortableand free from any interruptions. Designed multilane divided highways withpartial access control and assure a high level of service/passage.

Other highways, as a rule, has no restrictions on access and are comprised of

two basic groups:

Multi-lane highways, with more than two traffic lanes, can serve a widerange of traffic volumes, can be divided or undivided, and depending onthe initial design, can be converted into higher level facilities such as high-speed highway freeways. Partial access control may be warranted onsome road sections to maintain high level of service.

Two-lane highways, are flexible facilities in terms of their functionalpurpose and a range of design speeds but limited in terms of trafficcapacity. When traffic volumes warrant, truck climbing lanes are provided.

Low volume roads primarily serve traffic to and from isolated soums, baghs,

recreational sites and resource development areas. Depending on thespecific function, these roads are designed as one or two-lane facilities,generally, suitable for operation at slow speeds.

1.10 Conventional highways are subdivided into four technical categoriescorresponding to ranges of traffic volumes and level-of-service requirements;Table 2 establishes a relationship between highway functional classes anddesign types and categories that are adequate to satisfy functional requirementsaccording to the classification system in Par. 1.7.

1.11 Passenger car equivalency factors should be selected for all commercial vehiclesand busses as follows:

level terrain - 2

rolling terrain - 4

mountainous terrain - 8

1.12 Selection of the number of traffic lanes for multi-lane highways and roads ofcategories lll-IV highways and of low volume roads should be based on level-of-service criteria in Table 2.


1.13 The design type of a new or a reconstructed highway is determined by itsfunctional classification and is detailed in the course of a feasibility study basedon a 20-year design period.


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1.14 The initial year of the projected design period should be taken as the year whenthe road is expected to be commissioned.

1.15 Basic design solutions related to vertical and horizontal alignment, dimensions ofbridges and of other road structures should be made taking into account futuredevelopments beyond theinitial road design period.

1.16 Selection of the number the traffic lanes for multi-lane highways, types ofintersections and interchanges should be carried out taking into account thepossibility of a staged construction as traffic volume increases.

Design vehicle dimensions

1.17 Public roads designed according to this standard are intended for road vehicleswith the following maximum dimensions: length of a single truck - up to 12 m andlength trailers up to 24 m; width - up to 2.5 m, height - up to 4m.

Table 2

Functional and technical classifications of highways and corresponding operationtraffic characteristics and traffic volume

Road typeNumberof lanes

Functionalclassification

2 Level-of-

service

Divided/undivided

3 Accesscontrol

Expressway1 Multi-lanes

Arterial roads A Divided Restricted

Category I1 Multi-lanes

Arterial roads B Divided orundivided

Partiallyrestricted

Category IIMulti-

lanes

Arterial roads B Undivided UnrestrictedCategory III

Two-lanes

Arterial/regionalroads

B Undivided Unrestricted

Category IVTwo-lanes

Arterial/regionalroads

C Undivided Unrestricted

Category V1-2

lanesRegional roads D Undivided Unrestricted

Note:

1Multi-lane highways: number of lanes greater than 2

2Volume to capacity ratio is defined in par 1.2

3 Definition of restricted access

2. HIGHWAY OPERATIONS AND TRAFFIC SAFETY

General principles

2.1 Design of new highways and reconstruction and rehabilitation of existing highwayfacilities must include measures directed both at the reduction of traffic accidentrisks and mitigation of accident severity.

2.2 Feasibility studies carried out in connection with construction, reconstruction andrehabilitation of highways must consider alternative traffic safety measures

weighing their effectiveness in relation to costs.


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2.3 Feasibility studies carried out in connection with construction, reconstruction andrehabilitation of highways must consider alternative traffic safety measuresweighing their effectiveness in relation to costs.

2.4 Highway safety features that must be considered in the course of a feasibilitystudy for construction and reconstruction of highways to achieve the most

significant reduction in risk of traffic accidents include: Full or partial access control

Minimizing the number of at-grade intersection

Providing grade-separated railway crossing

2.5 The following safety related issues must be addressed in the course of highwaydesign:

Traffic safety onvertical and horizontal curves and grades

Visual orientation of drivers, including adequate sight distances atintersections.

Necessary skid resistance of the roadway surface in all-weatherconditions.

Adequate roadside safety to provide an opportunity for a vehicle leavingthe travelway in emergency situations to recover or stop.

Develop schematics for installation of traffic barriers, channelization, roadmarkings, locations of traffic signs, automated systems to control trafficlights and driver advisory systems.

Safe locations for intersection and junctions with necessary facilities tocontrol traffic operations.

Pedestrian crossings, bicycle paths, rest areas, bus stops, etc. Fencing at locations where instances of animalcrossing are frequent.

The use of additional traffic lanes on two-lane highways with heavy traffic.

The use of left-turn lanes with divisor medians at the access tointersections.

The use of middle lanes on roads with odd number of lanes for left turns.

2.6 Acceptance f minimum standards according to Par. 4.22 for new design orreconstruction of vertical alignment, horizontal alignment and cross sectionelements should be accompanied by a study of alternative solutions, taking intoaccount highway safety.

2.7 Utilization of steep embankment slopes in conditions envisaged in Par. 6.18should accompanied by an economic analysis weighing the interests of trafficsafety and the value of additional right-of-way required.

2.8 Ensuring an adequate visibility range at accesses to at-grade intersections usingvisibility requirements higher than minimum values of Par. 5.11.

2.9 Road design must include development of schematics for installation of roadsigns indicatingtheir locations and installation methods. For roads with high andintermediate surfacing, project design documents must also include a roadmarking scheme. The ratio of road markings on the straight section will be 3:1, attransition curve 1:3, at curves with 1000-600m radii 1:3 and at curves with more

than 1000m 3:1. The schematics for road markings must be coordinated withlocations of roads (particularly, in areas with a prolonged snow cover).


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Installation of all traffic control devices must be carried out according to MNS4596-2007. To ensure traffic safety, there must be no commercial advertising onarterial highways.

2.10 Distinctive color surfacing is recommended for marking pedestrian crossings, busstops, speed change lanes, additional lanes on grades, vehicle stopping lanes,

roadway in tunnels and under overpasses, at railway crossings, small bridgesand other sections where obstructions are poorly visible on the pavementbackground.

Roadway lighting

2.11 Stationary electric lighting should be installed on highway sections withinpopulated areas. Provided there is a possibility of using existing powerdistribution networks, lighting should also be installed on large bridges, busstops, intersections between arterial roads, intersections of arterial roads withrailways, on connecting branches of interchanges and on roundabouts.

If a distance between adjacent lighted sections is less than 250 m, it is

recommended to provide a continuous lighting to avoid alternation of lighted andnon-lighted areas.

2.12 The average luminance of the road surface on sections outside of populatedareas, including sections of large and medium bridges, should be 0.8cd/m2 formulti-lane highways, 0.6 cd/m2 two-lane highways and 0.4 cd/m2 on connectingbranches of interchanges.

The ratio of the maximum luminance of the roadway surfacing to the minimumluminance should not exceed 3:1 on sections of multi-lane highways and 5:1 onroads of other types.

The average horizontal illuminance of road sections of a length of up to 60 munder overpasses and bridges should be 15 Ix during dark hours, and the ratio of

the maximum illuminance to the average-should be not more than 3:1.

Lighting of highway sections within populated areas should comply withrequirements as specified for those within the cities.

Lighting installations on intersections between highways and railways shouldconform to lighting requirements as specified in the system of safely standardsfor railways.

2.13 Highway light posts can be installed on the median of width in excess of 5 m andshielded by guardrail.

2.14 Highway lighting should be switched on when the level of natural illuminancedecreases to 15-20 Ix and lighting should be switched off when the level ofnatural illuminance increases to 10 Ix.

2.15 Management of the highway lighting network should be carried out usingcentralized remote control systems.

3. ENVIRONEMNTAL PROTECTION

Environmental impact assessment

3.1 The environmental consequences of constructing new or reconstructing anexisting road must be determined through a multidisciplinary environmentalassessment of the project impacts and development of a mitigation plan.

3.2 The environmental impact assessment road project must be completed in the

course of the project feasibility study. Mitigation plan must be prepared during


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the detailed project design stage. Road works cannot be started without reviewandapproval of project documents by environmental assessment agencies.

3.3 The environmental impact assessment of road projects must consider negativeimpacts from the following sources related to highway operation, and roadconstruction works:

Transport pollution:emission of pollutants into the atmosphere, traffic noise androadside pollution as a result of drainage from the roadway.

Landscape changesas a result of road construction: terrain changes, alterationsin drainage patterns, changes in ground water level, soil sion, alterations inland use patterns, demolition or reconstruction of existing structures.

Impacts during construction: air and ground pollution due to constructionmachinery; construe! noise; dust spreading; reservoir pollution and damage totemporary acquired land.

3.4 Consequences of environmental impacts should be evaluated for the followingelements:

Natural surrounding.

atmospheric composition; dust content; level; composition of surface drainage;water quality in reservoirs; ground water quality; ground water levels and flowpatterns; ground stability; resistance to erosion; preservation of soil fertility;plants, animals (trees, bushes, a grassy cover, agricultural plants, animals, fish,water ecosystems).

Socio-economic:

population (interests of community and of individuals); land use (housingaccommodation, agriculture, forests, recreation, industrial enterprises, etc.);transport infrastructure (transport network, availability of social units for

transport); units under special protection (monuments to a history and culture,archeological units, reservations, natural phenomena sites); aesthetic aspects ofthe landscape (natural, artificial urbanized landscapes).

3.5 As a result of determining the range of pollutants spreading on the area adjacentto the road, boundaries of the zone of elevated influence should be establishedwhere, under a combination of unfavorable factors, pollution or environmentalchanges can exceed legal limits specified in appropriate regulatory documents orproject-specific limits established as a result of a special study.

3.6 The width of the zone of elevated road influence along the entire length if multi-lane highways should be determined by calculation of spreading of the mostdangerous pollutants such as exhaust gas and traffic noise. For other roads,such calculations are performed only for sections passing through populatedareas and specially protected lands.

3.7 For the purpose of narrowing the zone of elevated road influence it is necessaryto make use of special protective structures (noise-protective screens, guardrails,banks), multilane wood and bushes planting or special roadbed design (cuts,high embankments).

Results of environmental impact assessment, including effects of mitigationmeasures and protective structures, must be used in preparation of terms andconditions for land utilization. Solutions being accepted as a result of design workshould be subjected to coordination both with local environmental protection

authorities and public.


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3.8 The highway route location should be selected on the least valuablearable lands, preferably along boundaries of landscapes. As a rule, the roadlocation for transit traffic must not be selected through protected watershedsand populated areas. Places of mass residence and reproduction of wildanimals, birds, aquatic animals should be outside of the zone of a road influencewhich can be approximately taken as 10 times the width of the zone of elevatedroad influence.

Construction of special structures (fences, cattle crossings) or introduction oftraffic control measures such as limiting speed, time of traffic, etc., should beimplemented when a road crosses a habitual path animal migration.

3.9 The highway route for bypasses of populated areas should be located from thelee side, using predominant wind direction during the time of the year whenconditions are most unfavorable from the point of view of air quality.

3.10 Design solutions for the roadbed, drainage structures and facilities must take intoaccount, environmental consequences of changes in surface drainage,groundwater levels, snow accumulation. It is necessary to prevent formation of

reservoirs with impaired drainage leading to bogginess.

There should be no changes in groundwater level in areas of forests, waterreservoirs, agricultural areas and in boggy areas of agricultural significance.

3.11 During construction of roads on boggy or irrigated areas, drainage or flooding oflands due to cuts or embankments is permissible only when suchactions are compatible with land reclamation projects within the highway area.

3.12 Diversion of flows from different watersheds into a single drainage basin must notbe carried out in erosion-prone areas.

3.13 Fertile soils within areas of the right-of-way to be occupied by roadbed and otherroad structures as well as in borrow areas, quarries and other workings should be

stripped and stored in piles in the designated location. The depth of fertile soilstripping should be determined in the course of site investigation.

Removal of the fertile soil layer is not necessary when it is permanently frozen,from swamp areas, slopes steeper than 1:3.

Note: Clayey to sandy-loam humus soils with physical and chemical compositionsconforming to requirements of MNS are referred to as fertile soils.

Fertile soils can be used for stabilization of road-bed slopes, recultivation ofborrow areas and quarries, for grass sowing. The surplus volume of humus soilsshould be disposed of if it cannot be marketed.

3.14 Selection of design solutions for structures and buildings in road-related areasshould be carried out taking into account their visual qualities compatibility withnatural surrounding.

It is necessary for aesthetic purposes to avoid disruptions of a landscape,introduction into natural landscape of unusual geometric forms (large geometricvolumes, bright colors, changes in a natural relief, etc.) and the destruction ofvisually attractive natural complexes and picturesque elements. The natural formand variable steep pitch should be applied to slopes of deep excavations andhigh embankments.

3.15 Highway design tor traffic volumes in excess of 1500 veh/day within the limits ofpopulated areas and for roads with traffic volume more than 700 veh/day near

protected water reservoirs and recreational facilities must stipulate measures forcollection and diversion of discharge from roadways, bridges, rest areas, etc.


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The discharge collected outside the protected area of a water reservoir should bediverted into accumulation wells with subsequent discharge into reservoirsthrough soil filters alter primary sedimentation. The quality of water in reservoirsshould meet regulatory requirements.

3.16 Highway design projects must stipulate preservation of historic and cultural

monuments located within the construction area - ancient structures, burialgrounds, archeological units, objects of special attention of the local population,etc., and also unique natural sites - special geological forms, water sources,valuable specimens of trees, etc.

3.17 Utilization of industrial wastes should be carried out taking into account theirpossible toxic properties and radioactivity. Utilization of organic, water-soluble,chemically active industrial and household wastes requires approval ofappropriate environmental authorities and is feasible in structures when thepossibility of their transport by drainage or percolating water is excluded.

Salvageable solid waste discarded during augmentation of existing road into newshall be sorted out at location agreed with concerned local authorities and

environmental agency for purpose of reuse.

4 BASIC DESIGN CONROLS AND REQUIREMENTS

Design speed and loads

4.1 Design speed is the maximum safe speed that can be maintained over aspecified section of highway when conditions are so favorable that the designfeatures of the highway govern.

4.2 Selection of speed for purposes of designing road elements that are speed-dependent should be carried out according to Table 3.

4.3 Design speed values in Table 3 are minimum permissible. Higher design speeds

can be adopted provided that design speed on adjacent section of highwaysshould not differ by more than 15%.

When higher than minimum design speeds are considered, the followingguidelines should be used:

The driver expects to be able to drive at certain maximum speeds consistentwith the functional purpose of the highway.

The design speed selected for a highway, more than any other design controlhave a major impact on-all facets of geometric design, and, consequently onconstruction costs.

Horizontal and vertical alignment are permanent features of the road and

frequently cannot be altered in the future, particularly on roads designed to fitthe landscape or when there are design restrictions related to abuttingdevelopment.

Benefits of higher degree of safety, access and mobility must weigh againstthe environmental, right-of way-and cost impacts.

4.4 With the exception of low volume roads, pavement structural design for all roadclasses and categories should be carried out for 100 kN singlewheel, single axle load. If vehicles with an axle load over 60 kN are not expectedon roads of category IV during a significant portion of the design period, theirstructural design should be carried out for 60 kN single wheel load. Minimumdesign axle load for low volume roads should be 60 kN (single wheel, single

axle). Pavement structural design using loads specified in Par. 4.4 should be


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carried out according to design manuals complying with design principlesdetailed in Section 7.

Table 3

Design speed for motor roads

Road type Design speed km/h

Flat Rolling Mountainous

Expressways Multi-lane 140 120 80

Category I Multi-lane 120 100 60

Category II Multi-lane 120 100 60

Category III 2 lanes 100 80 50

Category IV 2 lanes 80 60 40

Category V 1-2 lanes 60 40 30

Cross Section Elements

4.5 Basic cross section elements for all types and categories of roads should betaken according to Table 4.

Number of traffic lanes

4.6 The number of traffic lanes tor multi-lane highways should be determined on thebasis of capacity analysis and in accordance with the required level of service.

Lane Width

4.7 If design speeds higher than minimum in Table 3 are selected, wider lanes

compared to those specified in Table 4 can be adopted based on thefollowing guidelines:

Wider lanes increase highway capacity.

The lane width and pavement conditions more than any other highwayelement positively affects safety and comfort of drivers.

Desirable clearance between trucks during overtaking on a two-lane highwayis when the lane width is 3.75 m.

In general, increase in lane width above 3.75 m does not give additional trafficsafety benefits.

4.8 When reduced design speed is selected according to conditions of Table 3 for

rolling and mountainous terrain, lane width of category II and III roads can bereduced to 3.3 m.


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Table 4

Basic dimensions of cross section elements

Road typeTraffic lanes Shoulder dimensions, m Minimum

medianwidth, m

Number oflanes

Lane width,m

Usable Paved strip

Expressway 4 3.75 3.75 0.75 5Category I 4 3.75 3.5 0.75 2Category II 2-3 3.75 3.0 0.75 0Category III 2 3.5 2.0-2.5 0.5 0Category IV 2 3.0 1.5-2.0 0.5 0Category V 1 4.5-5.0 1.0 0 0

Note: Type IV and V shall be provided for local roads

4.9 As a rule, right-turn and left-turn lanes should be of the same width as trafficlanes or 0.2 m narrower. Left-turn lanes adjacent to a median can be 3 m wide.In conditions of restricted right-of-way, widths of turning lanes can be reduced to3 m at the most.

4.10 Climbing lanes for trucks on two-lane highways should be provided in conditionsof mixed traffic if one of the following conditions exist:

Up-grade traffic volume exceeds 200 vehicles per hour and up-grade trucktraffic is in excess of 200 vehicle per hour for more than 50 hours in ayear.

A 15 km/hr or greater speed reduction is expected for a typical truck.

A low level of service (E or F) exits on an upgrade section longer than 0.5 km.

A reduction of two or more levels of service on an upgrade section isexpected.

The width of climbing lanes should be equal to the width of the basic traffic lanes.

Length of a transition section to a widened roadway should not be less than 60m.

4.11 Passing lanes are provided on two-Iane highways with significant volume of slowmoving vehicles to facilitate passing maneuvers. Standard widths are the sameas the adjacent lane width or 0.2 m less and not less than 3.3 m.

4.12 On one-lane low volume roads turnouts should be provided with spacing not lessthan stopping sight distances.

Turnouts should be provided on two-lane low volume roads on sections withgrades exceeding 60%.

Transition to a widened section on approach to a turnout should not be less than

10 m.

4.13 Surfacing on shoulders and on the stabilize pad of medians should differ in colorand appearance from the roadway surfacing or it should be distinguished bymarkings.

Cross-slopes

4.14 Roadway cross-slopes (excluding superelevated sections of horizontal curves)should be specified depending on the number of traffic lanes and the climaticconditions according to Table 5.


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Table 5

Pavement cross slopes

Climatic zone I II III IV V

Multi-lane highwaysTwo-way cross slopes

0.15 0.02 0.02 0.025 0.015

One-way cross slopesFirst & second lane from

the median0.015 0.02 0.02 0.02 0.015

Third and subsequentfrom the median

0.02 0.025 0.025 0.025 0.02

Two-lane highway 0.02 0.02 0.02 0.02 0.0154.15 Cross-slopes for low volume roads should not be less than values indicated in

Table 6.

4.16 Shoulder cross-slopes for crown sections should be 1.2% greater than theroadway cross-slope. The following values of shoulder cross-slopes should beused, depending on the type of shoulder surfacing:

concrete 3%

bituminous surfacing 3%

gravel, aggregate surfacing 4%

Table 6

Pavement cross-slopes for low volume roads

Surfacing type Cross slope, %

Surfaced road 2-4Gravel, aggregate, earth 4

4.17 Shoulder cross-slopes for low volume roads should not be less than valuesindicated in Table 6.

4.18 Roadway cross-slopes on superelevated sections should be selected according tohorizontal curve radii as per Table 8. In situations of very difficult terrain or indifficult construction conditions, highway sections with variable ("stepped-up")superelevation and widened roadways can be individually designed.

4.19 Superelevation is not required when horizontal curve radii are in excess of valuesin Table 7.

Table 7Minimum radius on horizontal curves not requiring superelevation

Design speed, km/h Minimum radius, m


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As a rule, superelevation on multi-lane highways should be designed withseparate cross-slopes for roadways of opposite direction and with necessaryadjustments in median cross-slopes.

Cross-slopes of inner shoulders on superelevated sections should be equal toroadway cross-slopes and cross-slopes of outer shoulders should be opposite to

roadway cross-slopes. Transition curve from shoulders of normal crown sectionsto shoulders corresponding to single camber should be carried out, as a rule, asper Table 8.

Additional longitudinal slope of the roadway edge relative to design grade ontransition sections should not exceed the values given in Table 11.

Horizontalcurve

radii,m

Superelevation %, for design speed, km/hr, Transition curve length, m

30 40 50 60 80 100 120 140

%

LT

%

LT

%

LT

%

LT

%

LT

%

LT

%

LT

%

LT

2lanes

2lanes

2lanes

2lanes

4lanes

-2lanes

4lanes

2lanes

4lanes

2lanes

4lanes

2lanes

4lanes

7000 NC - NC

- NC

- NC

- - NC

- - NC

- - NC

- - RC - -6000 NC - NC - NC - NC - - NC - - NC - - NC - - RC - -5000 NC - NC - NC - NC - - NC - - RC - - NC - - RC - -3000 NC - NC - NC - NC - - NC - - RC 16 26 2.3 22 33 2.5 26 392000 NC - NC - NC - NC - - RC 14 22 2.5 20 31 3.3 31 47 3.7 38 671500 NC - NC - NC - NC - - 2.2 16 24 3.1 25 38 4.2 40 60 4.9 48 731200 NC - NC - NC - RC 12 18 2.7 19 29 3.7 30 45 5.0 47 71 5.5 58 861000 NC - NC - RC 11 2.1 13 19 3.1 22 33 4.2 34 52 5.5 53 80 6.0 62 93900 NC - NC - RC 11 2.3 14 21 3.4 24 37 4.5 37 55 5.8 55 82 Rmin =950800 NC - NC - RC 11 2.5 15 23 3.6 26 39 4.9 40 60 6.0 57 85700 NC - RC 10 2.1 12 2.9 17 25 4.0 29 43 5.2 43 64 Rmin =755600 NC - RC 10 2.4 13 3.1 19 28 4.3 31 46 5.6 46 69500 NC - 2.1 11 2.6 16 3.5 21 32 4.6 35 52 5.9 46 72400 RC 10 2.5 13 3.3 18 4.0 24 36 5.3 38 57 Rmin =435

350 RC 10 2.8 14 3.6 20 4.3 26 38 5.6 40 60300 RC 10 3.1 16 3.9 22 4.6 28 41 5.9 42 64

250 2.3 11 3.5 17 4.2 23 5.0 30 45 6.0 43 66

220 2.5 12 3.7 18 4.4 24 5.2 31 47 Rmin =250200 2.8 13 3.9 20 4.7 26 5.5 33 50

180 3.0 14 4.1 21 5.0 27 5.7 35 52 Note:

160 3.3 15 4.3 22 5.2 29 5.9 37 53 % Superelevation slope140 3.5 17 4.5 23 5.4 30 6.0 38 54 LT Transition curve length, m

120 3.8 18 4.9 25 5.7 32 Rmin =135 NC Normal Cross-slope

100 4.4 20 5.2 27 6.0 33 RC Cross-slopes of shoulders should be equal toroadway cross-slopes90 4.2 20 5.4 28 6.0 33

80 4.5 22 5.6 29 Rmin =90

70 4.7 23 5.8 30

60 5.0 24 6.0 3150 5.4 26 Rmin =65

40 5.8 28

30 6.0 29

Note:

If two adjacent horizontal curves are in close proximity and rotating in the samedirection, and there is no straight section between them or its length is insignificant,single camber cross section should be adopted continuously over the entire length ofboth curves.

In areas where snow cover is present during a short time period and instances ofblack ice are infrequent, the highest superelevation of 80% can be used.

Transition curve length (LT) has been taken in correspondence with Clotoid

methodology, hence it does not pertain to Miting method.


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Travelway widening

4.21 For horizontal curves of radius 1000 m and less, it is necessary to introducewidening of the travelway on the inner side of the curve by reducing shoulders insuch a way that the shoulder width should be is not less than 1.5 m for multi-lanehighways and not less than 1 m for other highways.

The values of complete widening on horizontal curves tor two-lane roadwayshould be adopted according to Table 9.

In instances of insufficient width of shoulders for specified travelway widening, anappropriate road bed widening should be undertaken. Widening the roadwayshould be carried out in proportion the distance from the beginning of thetransition curve in such a way that the complete roadbed widening is achieved bythe beginning of the circular curve.

Table 9

Lane widening on horizontal curves

Curveradii, m

Width of widening for vehicles and combination trucks with distance from frontbumper to rear axle, m

Allvehicles

Combination trucks


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longitudinal grades - not more than 30%;

sight distance for vehicle stopping - not less than 450 m;

horizontal curve radii - not requiring superelevation (according to Table 7);

vertical curve radii: not less than 30,000 m for crest curves; and not less than

8000 m for sag curves;lengths of vertical curves: crest curves - not less than 300 m; sag curves - notless than 100 m.

Transition curves should be used for design of vertical alignment when thealgebraic difference of grades exceeds more than 5% for multi-lane highways,more than 10%, for roads of category III and more than 20% for other roads.

In all cases when due to local conditions people or animals can appear on theroadway, the lateral visibility of 25 m from the edge of a roadway should beprovided for multi-lane highways and 15 m for other roads.

4.23 If, due to the conditions of an area, it is not possible to meet the requirements, of

Par. 4.22, or their implementation is connected with significant volumes of workand cost of road construction, it is permissible to reduce design standards on thebasis of technical and economic comparison of alternatives, taking into accountthe instructions, stated of Par. 2.6. In this case, minimum permissible standardsshould be adopted according to Table 10, on the basis of the design speedsselected according to road types as per Table 3.

N o t e s :

1. In instances of sharp changes in alignment of two-lane roads in mountain terrain,it is permissible to use serpentine-type design.

2. In very difficult conditions of mountain terrain (excluding areas with absolute

altitude more than 3000 m above sea level), maximum grades can be increasedcompared to values specified stated in Table 10, but not more than by 20% forsections ofthe length of up to 500 m.

3. If multi-fane highways in mountain and rugged terrain are designed with separateascending and descending roadways, grades for descending alignment can beincreased compared to grade for ascending alignment, but not more than by20%.

4. Maximum grade on approach sections to tunnels in mountain area should notexceed 45% over a distance of 250 m from the tunnel portal.

4.24 Transition curves should be used lot horizontal curves with radius, 3000 m andless. Guidelines f the section on "Landscape design" should be followed fordesign of transition curves. Minimum length of transition curves should beadopted according to Table 8.

4.25 Maximum grades on sections with horizontal curves of small radii should bedecreased according to Table 12, compared to standards given in Table 10.

4.26 To ensure adequate sight distances on the inner side of horizontal curves, widthof forest and bush clearing, magnitude of embankment slope steepening andrelocation of structures should be determined by calculation; slopes must besteepened up to the top level of the roadbed edge.

4.27 Length of a section with prolonged grade in mountain areas is determined basedon the magnitude of grade and must not exceed values given in Table 13.


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Table 10

Minimum parameters for horizontal and vertical alignment

Designspeed,km/h

Max.grades,

%

Minimum sight distances

Minimum curve radii, mHorizontalalignment

Vertical alignment

Requiredsuperelevation,

%Crest

Sag

Forstopping

Forapproaching

traffic

Forovertaking

60 40Basic

sectionsMountain

terrain

140 30 280 - - 1250 1500 17000 7200 3600120 40 250 450 800 750 900 14000 6200 3100100 50 200 350 680 450 550 9000 4800 240080 60 140 250 560 250 300 4500 3200 160060 70 85 170 420 150 150 1600 1800 900

50 80 70 130 340 100 100 1100 1400 70040 90 55 110 290 60 60 700 1000 50030 100 45 90 230 30 30 500 800 400

Note: 1. The minimum sight distance for stopping should ensure visibility of any object of the height of0.2 m and greater located in center line of a traffic lane, assuming the height of vehicle operator's eyes

1.2 m from roadway surface.

Table 11Longitudinal slope of the roadway edge and centerline

on transition sections

Design speed, km/h Slope, %

40 0.70

50 0.65

60 0.60

70 0.5580 0.51

90 0.47

100 0.44

110 0.41

120 0.38

130 0.36

Table 12Grade reduction on small radii curve

Curve radii in plan, m 50 45 40 35 30

Decrease in the largest longitudinal grades against

the standards stated in Table 10, % not less than

10 15 20 25 30

Note: Serpentine curves radii less than 30 m can only be used on roads of categoriesIV and V, prohibiting vehicles of length over 11 m.

4.28 On difficult section in mountain areas, prolonged grades (more than 60%) can bepermitted with inclusion of sections with decreased longitudinal grades (20% andless) or introduction of areas for vehicle stopping with a spacing between suchareas not greater than the lengths of sections, as specified in Table 13.

Dimensions of areas for vehicle stopping are determined by calculation, butshould be specified for not less than for 3 - 5 trucks. Their location is determinedto assure sufficient space for safe parking, excluding a possibility of a talus, rockfalls and, as a rule, at locations with water sources.


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Irrespective of availability of stopping areas, escape ramps, should be providedon prolonged downgrades exceeding 50%, to be located before sharp curves atthe end of a downgrade, as well as on downgrade straight sections every 0.8 -1.0km.

Geometric elements of escape lamps are determined based a safe stopping

condition of combination trucks.Table 13

Permissible maximum length of prolongedgrades in mountainous terrain

Longitudinalgrade, %

Permissible max. length, with altitude above sea level, m1000 2000 3000 4000

60 2500 2200 1800 150070 2200 1900 1600 130080 2000 1600 1500 110090 1500 1200 1000

4.29 The design standards serpentine-type roads should be adopted according toTable 14.

Table 14

Design standards for serpentine type roads

Parameters of serpentine type roadsDesign standard for serpentine type roads

at design speed, km/h30 20 15

The smallest radius of curves in plan, m 30 20 15Transverse roadway grade onsuperelevations, %

60 60 60

Length of transition curve, m 30 25 20Roadway widening, m 2.2 3.0 3.5The largest longitudinal grade withinhairpin curves, %

30 35 40

4.30 Distances between the end of one serpentine curve and the beginning of anothercurve should be selected as large as possible, but not less than 400 m for roadsof categories III, 300 m for roads of category IV and 200 m for low volume roads.

4.31 The travelway on serpentine curves can be widened by 0.5 m using the outsideshoulder, and the remaining part of widening should be accomplished at theexpense of the inside shoulder and additional roadbed widening.

Landscape design

4.32 Alignment of a highway should be designed as a smooth curve coherent withfeatures of the surrounding landscape and with coordinated horizontal, verticaland cross-section elements, to facilitate their positive impact on traffic conditionsand the visual perception of the road.

To ensure road smoothness, it is necessary to observe principles of landscapedesign and to use rational combinations of elements defining horizontal andvertical alignment.

Road smoothness should be checked by calculating the visible curvature of thecenterline of the road and a visible width of the roadway at an extreme point in

the projection plane. To assess the visual clarity of the road, it is recommended toconstruct a perspective sketch of the road.


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Combinations of horizontal and vertical curves with grades that create animpression of a fall must be avoided in all cases.

4.33 As a rule, horizontal and vertical curves should be combined. Also, horizontalcurves should be 100-150 m longer than vertical curves and a shift of curvepeaks should be not greater than 1/4 of the length of the shortest curve.

Junctions of end points of horizontal curves with starting points of vertical curvesshould be avoided. Distances between curves should be not less than 150m. Ifa horizontal curve is at the end of a downgrade section of a length in excess of500 m and with a grade more man 30%, its radius should be increased by afactor not less than 1.5 compared to values given in Table 10, matchinghorizontal curves and sag vertical curves at the end of the downgrade section.

4.34 The length of straight sections should be limited according to Table 15.

Similarly, the total length of tangent sections, conjugated by a short horizontalcurve, should be limited.

Table 15

Maximum length of tangents between curves

Road categoryUltimate length of straight line in plan

in area, mFlat area Rolling terrain

Multilane highway 6000 2000-3000Two lane highways 5000 1500-2000Low volume roads 3500 1500

4.35 Radii of adjacent horizontal curves should differ by a factor of not more than 1.3.Parameters of adjacent transition curves are recommended to be the same.

4.36 In case of small turn angles in horizontal alignment, it is recommended to use theradii of circular curves according to Table 16.

4.37 Long straight sections between vertical curves should not be used. Their ultimatelengths are given in Table 17.

4.38 Introduction of a short tangent section between two horizontal curves of the samedirection is not recommended. When its length is 100 m or less, it is desirable toreplace both curves by one curve of a largerradius. When the length is 100- 300m, it is recommended to replace the tangent by a longer transition curve.Tangent section, as an independent element of a horizontal alignment, ispermissible on arterial roads (Type I & II) when section length is in excess of 700m, and or other roads (Type III & IV) when its length is greater than 300m.

Table 16

Curve radii for small angle of change in horizontal alignment

Angle ofturn, deg

1 2 3 4 5 6 7-8

Min.curve

radius, m30000 20000 10000 6000 5000 3000 2000


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Table 17

Maximum length of longitudinal straits between vertical curves

Radius ofsag

vertical

curve, m

Algebraic difference of longitudinal adjacent grades, %

20 30 40 50 60 80 100The longest length of straight section in vertical alignment, m

For multi-lane highways4000 150 100 50 0 0 08000 360 250 200 170 140 11012000 680 500 400 350 250 20020000 850 700 600 55025000 900 800

Two-lane highways2000 120 100 50 0 0 0 06000 550 440 320 220 140 60 0

10000 680 600 420 300 20015000 800 600

Bicycle paths and sidewalks

4.39 Bicycle paths should be designed along constructed or reconstructed roads onsections, where traffic volume is less than 4000 pcu/day, and bicycle or mopedtraffic volume in one direction for the first five years of road service reaches 400bicycles (mopeds) per hour or 1000 units per day.

As a rule, bicycle paths of the width not less than 2.2m should be designed forone-way traffic on an independent roadbed, at a foot of the embankment oroutside of cut slopes, as well as on berms (in exceptional cases - at a distance

not less than 1 m from a roadway edge).

Single lane bicycle paths should be located or the windward side of the road(based on prevailing winds in summer time) and two-lane bicycle path - on bothsides of the road.

In restricted space conditions and on accesses to highway-related structures,bicycle paths can be constructed on shoulders. In these cases, shoulders shouldb separated from a roadway by a curb of the height of 0.20 - 0.25 m, and thepaths should be located at a distance not less than 0.75 m from a vertical face ofthe curb.

4.40 Pavements tor bicycle paths should be surfaced with binder-stabilized aggregate,

as well as crushed stone, gravel aggregates, soil-gravel mix, brickbats orporcelanites. When economicall feasible, asphalt concrete or cement concretecan be used as bicycle path surfacing.

4.40 On approach to populated areas and on sections within ulated areas wherethe design traffic volume is 4000 pcu/day and greater, pedestrian sidewalksshould be designed, as a rule outside the roadbed.

5. INTERSECTIONS AND JUNCTIONS

5.1 Highway intersections and junctions, as a rule, should be located in free areasand on tangent sections of intersecting or joining roads.

Longitudinal grades on approach to intersections and junctions over the length of

stopping sight distance (according to Table 10) should not exceed 40% forconventional highway and 30% for expressways.


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5.2 The number of intersections and junctions or international and regional roadsshould be as small as possible. As a rule, intersections and junctions onexpressways and international highways should be spaced not closer than 10 kmoutside of urban areas, not closer than 5 km on national roads and, not closerthan 2 km on regional roads.

At-grade intersections and junctions5.3 At-grade intersections outside of urban areas, as a rule, must be designed as

unsignalized road crossings and junctions controlled by traffic signs defining theright of way.

5.4 If traffic volumes on major and minor roads exceed values given in Table 18, thecapacity of at-grade intersection should be determined through individualcapacity calculations.

Table 18

Unsignalized at-grade intersection capacityfor uninterrupted flow condition

Road type Design hourly traffic volume, two-way, vehicles per hourTwo-lane road 400 500 650

Minor cross road 250 200 100Multi-lane road 1000 1500 2000

Minor cross road 100 50 25

5.5 Traffic channelization by means of safety islands separating traffic streamsthrough at-grade intersections and junctions must be used when the sum ofprojected traffic volumes exceeds 2000 pcu.

Unchannelized at-grade intersections and junctions can be utilized when the total

projected traffic volume is less than 2000 pcu. At-grade roundabouts can beused in cases, when traffic volumes on intersecting roads differ by not more than20%, and the number of left turning vehicles is not less than 40% on intersectingroads.

5.6 Delineation of traffic lanes on the major roads outside of urban areas should beprovided by uncurbed islands, unless pedestrian traffic warrants otherwise.

5.7 Grade-separated pedestrian crossings (overpasses and underpasses) on multi-lane highways should be provided when pedestrian traffic is in excess of 200persons/hr. Pedestrian fences should be provided in places of pedestriancrossings.

5.8 Entrances and exits of all roads, with the exception of roads of category IV and

low volume roads, must be surfaced:

over a length of 50 m in case of sand, sandy loam and light loamy soils;

over a length of 100 m in case of black earths, clayey, heavy and silty loamysoils.

The length of entrances and exits for roads of category IV should be surfacedover half the length specified for roads of higher category. Shoulders onentrances and exits over distances established in this paragraph should bestabilized over a width of not less than 0.5 m.

5.9 At-grade intersections and junctions, irrespective of intersection schematics,should be arranged at right or close to right angles. When traffic streams do notintersect, but diverge or merge, intersection can be arranged at any angle,provided sight distance requirements are met.


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5.10 Minimum radii of transition curves on at-grade intersections or junctions shouldbe chosen according to the type of major road, irrespective of the crossing angle:in case of exits from multi-lane highways not less than 25 m, exits from two-laneroad 20 m, and exits from low volume roads 15 m.

When design is for regular traffic involving combination trucks (more than 15% in

traffic stream), curves of radii 30 m should be used.5.11 Sight distances on approach to intersections and junctions should assure its

visibility over distances given in Table 10.

Location of T-junctions on sections of crest vertical curves and on the inner sideof horizontal curves should be used as an exception only.

Transition curves should be used for design of horizontal alignment on at-gradeintersections.

5.12 Speed-change lanes for left and right turns should be provided for at-gradeintersections and junctions at exits and entries of conventionshighways with traffic volume in excess of 1000 pcu, including entries to adjacent

buildings and structures adjacent to the highway: on multi-lanehighways with the volume of turning vehicles 50 pcu/day (for acceleration anddeceleration lanes respectively); on two-lane roads with traffic volumebeing 200 pcu/day and greater.

Speed-change lanes on conventional highways, with the exception of low volumeroads, should be provided at locations of trolley and bus stops, irrespective of thetraffic volume and at approach to fueling stations and rest areas when trafficvolume exceeds 1000 pcu.

5.13 Length of speed-change lanes for intersections and junctions should be selectedaccording to ble 19.

Interchanges5.14 Construction of grade-separated intersections and junctions (interchanges) must

be consistent with optimization of traffic services for the overall road network,taking into account local community interest and environmental restrictions.

Interchanges may be justified for one of the following reasons:

To provide access to freeways.

To increase capacity of a critical at-grade intersections.

To improve conditions of traffic safety by separating movements with highrelative speed.

To suit particular topography where an interchange can be built at acomparable cost to at-grade intersections.

To satisfy planning considerations for tin road network development.


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Table 19

Minimum length of speed change lanes for at-grade intersection

Designspeed, km/h

Grade, % Length at full width, m Taper length for accelaration& deceleration, mdown up for accelaration for deceleration

120

40 - 140 110 80

20 - 160 105 800 0 180 100 80- 20 200 95 80- 40 230 90 80

100

40 - 110 85 7020 - 120 80 700 0 130 75 70- 20 150 70 70- 40 170 65 70

80

40 - 75 65 6020 - 80 60 600 0 85 50 60- 20 90 45 60- 40 95 30 60

60

40 - 30 50 4020 - 35 45 40

0 0 40 40 40- 20 45 45 40

- 40 50 30 40

5.15 Grade-separated intersections and junction (interchanges) should be adopted, asa rule, on the basis of functional classification of intersecting highways (takinginto account the special status of freeways), according to Table 20.

Table 20

Intersections and junctions for different functional road classes

Expressway National (regional) roadsExpressway 1 1

National (regional) roads 1 2Notes:

1. Interchange as a rule.

2. Grade-separation can be provided.

5.16 For the purposes of reducing the total area occupied by grade-separations thefollowing ramp design speeds can be used.

Right-turn ramps of grade-separated interchange; multi-lane highways should bedesigned ensuring speeds not less than 60 km/hr and not less than 50 km/hr for

two-lane highways. In case of acute angle of road junction, ramps should bedesigned as a single curve, free of straight sections. Transitions using reversecurves can be used in exceptional cases only.

Curve radii of left-turn ramps (loops) of grade-separated interchanges of the"cloverleaf" type should be selected not less than 60 m for interchanges on multi-lane highways and not less than 50 m for two lane highways. Transition curvesshould be used on approach to tangent sections.

In particularly restricted space conditions at intersections of expressways withregional and local roads, 'partial cloverleaf" can be used with radii of left-turnramps reduced to 30 m.


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5.17 The roadway width over the entire length of left-turning ramps on grade-separated interchanges should be 5.5 m and 5.0 m on right-turning ramps withoutadditional widening on curves.

The width of shoulders on the inner inside of curves should be not less than 1.5m and 3 m on the outer side of curves.

Longitudinal grades on ramps should exceed 40%. Superelevation 20 - 60%should be used or single lane ramps, with design following general principles forsuperelevated sections.

Minimum radii of crest vertical curves on ramp should be selected in accordancewith design speeds as per Table 10.

Two-lane ramps should be designed based on the condition that every traffic laneis 3.75 m wide, and curve widening according to Table 9 should be used.

5.18 Speed-change lanes for left-turning roadways of cloverleaf type grade separatedinterchanges should be designed continuous over the length between adjacentramps, including the section of the grade separation structure.

On level tangent sections the length of deceleration lanes should be selectedaccording to Table 21and the length of acceleration lanes according to Table 22.

5.19 The width of transition lanes should be adopted as equal to the width of the mainlanes of the roadway. Lane stabilization on shoulders, adjacent to transitionlanes, should be carried out in accordance with Table 4.

5.20 Bridges and grade-separation structures on all road categories should bedesigned according to specific standards.

Table 21

Minimum length of deceleration lanes on grade-separated intersection

Designspeed, km/h

Taper length,m

Design speed of exit ramp, km/h40 60 80 100

Lane length, m60 55 7080 70 105 80100 85 145 120 80120 95 180 155 120 70140 105 210 185 150 105

Table 22

Minimum length of acceleration lanes on grade-separated intersection

Designspeed, km/h

Taper length,m

Design speed of entrance ramp, km/h40 60 80 100

Lane length, m60 5580 70 175 85100 85 330 230 70120 95 500 425 280 150140 105 640 610 490 350


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Intersections of highways with railroads and utility lines

5.21 As a rule, highway intersections with railroads should be designed outside ofrailway stations and shunting tracks, mostly, on tangent sections of intersectinghighways. Acute angle between intersecting roads should not be less than 60.

5.22 Railway intersections with highways of all types, with the exception of category IVand low volume roads, should be grade-separated.

To ensure traffic safety, intersections of category IV and low volume roads withrailroads should be designed as grade-separated in the following cases:

the intersection involves crossing three or more international rail tracks;

constructing railroads in excavations and when the standards for sightdistances are not according to Par. 5.23;

5.23 On unsignalized at-grade intersections of highways with railroads, sight distancesmust be such that that the vehicle driver located at a distance equal to thestopping sight distance from the intersection (according to Table 10), could see

the approaching train when it is a distance not less than 400 m from theintersection, while the engineer-driver of the approaching train could see thecenter of the intersection from a distance not less than 1000 m.

5.24 The roadway width of the highway on at-grace intersections with railroads shouldbe equal to the roadway width on the approach to the intersection, while on lowvolume roads the width of the intersection should be not less than 6.0 m over adistance of 200 m on both sides of the intersection.

A highway at an intersection with a railroad, when the railroad is on a curve andone rail is elevated relative to another, should have a flat surface, a vertical curveof large radius or a slope, starting and ending 2 m from outer rails on both sidesof the intersection.

Highways on approaches to intersections with railroads should be designed withgrades not exceeding 30% over a distance of at least 50 m from the intersection.

Guard posts and roadway gate posts on intersections should be installed at adistance not less than 0.75, and clearance gate posts should be installed at adistance not less than 1.75 m from the roadway edge.

5.25 Highway bridges over railroads should be designed satisfying requirements forobstruction-free distance, from railroad tracks as well as the followingrequirements:

ensuring adequate visibility of tracks and railroad signals according toconditions of train operation safety;

providing a drainage system taking into account stability of the railroadroadbed.

5.26 Distances from the roadway edge to utility poles and power transmission towersshould be not less than their height when utility lines and high voltage power linesintersect the roadway.

The minimum distance from the edge of the roadway to supports of utility andhigh voltage power lines located parallel to the highway should be equal to thesupport height plus 5m.

Supports of aerial power and telephone/telegraph lines can be installed at smallerdistances from the road in cases of severe space limitations that may occur in

built-up areas, gorges, etc. In this case, the horizontal distance to supports ofhigh voltage power lines should correspond to the following requirements.


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a) for intersection, the distance from any part of support to the bottom ofembankment or to the outside edge of the roadside ditch:

for multi-lane highways - 5 m for, voltage up to 220 kV and 10 m for voltage330-500 kV.

for other highways - 1.5, m for voltage up to 20 kV, 2.5 m - for voltage from 35to 220 kV and 5 m for voltage 330 - 500 kV.

b) for parallel road and power line alignment, the distance between the closestwire in undeviated state and the roadway edge:

for voltage up to 20 kV - 2 m, 4 m - for 35 -110 kV, 5m- for 150 kV. 6 m for220 kV. 8m - for 330 kV; and 10 m for 500 kV.

On highways, at locations of intersections with aerial power lines of the voltage330 kV and higher, no stopping signs should be installed these lines.

5.27 Vertical clearances between aerial telephone/telegraph wirelines and roadwaysurface should be not less than 5.5 m at locations of their intersection (during the

warm season). Elevations of power transmission lines above the roadwaysurface should be not less than values of Table 23.

Table 23

Elevation of power transmission lines above the roadway

Power line voltage, kV Elevation of wires


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6.2 The roadbed includes the following elements:

upper part of road bed (active subgrade layer);

embankment body (with slopes)

embankment foundation

foundation of the cut

cut slopes

surface drainage facilities

drainage facilities for lowering ground water

retaining structures or special geotechnical facilities or structures intended forroadbed protection against dangerous geological processes (erosion,scouring, mud flows, avalanches, landslides, etc.)

6.3 Roadbed design can be based upon and should take into account existing localgeotechnical practice, justifying adopted design solutions by documentedexamples of structures proven to be successful in situations analogous to designconditions.

Individual design solutions requiring specific justifications or detailed analysis ofdesign solutions dictated by existing practice is required in the followingcases:

for embankments more than 12 m high;

for sections of temporary flooded embankments crossing and sectionspassing through the permanent reservoirs and streams;

for embankments, constructed with peat removal on marshes of depth morethan 4 m or with transverse grades of the marsh bottom in excess of 1:10;

for embankments, constructed on weak foundations (cf. Par. 6.12);

when soils of high moisture content are used in embankments;

when elevation of pavement surface over the design water level is less thanthat specified in Par. 6.9.

for cuts with depth more than 12 m in soils and more than 16 m deep cuts inrock soils under favorable geologic conditions;

when geotextile Inter-layers are used;

when embankment is constructed on compressible foundation; when special-purpose pavement layers (insulating, waterproofing, drainage,

capillary-interrupting, reinforcing, etc.) are used for regulation of moisture-temperature regime in the upper part of the roadbed and in the pavementstructure;

for cuts in bedded formations with inclination of strata towards the roadway;

for cuts in water-bearing strata;

for cuts in silty soils located in areas of excessive moisture and in clayey soilsand soft rocks reducing strength and stability of slopes with time or as a resultweather and climatic conditions;

for excavations in swelling soils under unfavorable moisture conditions;


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for embankments and cuts in difficult soil and geological conditions such as:on construction on slopes steeper than 1:3, on sections with history oflandslides and rockslides, in gulches, karst zones, taluses, snow avalanches,icing, permafrost, etc.

Highway components to be designed individually include drainage facilities, retaining

structures and other protective facilities ensuring stability of the roadbed in difficultconditions.

Design groundwater level

6.4 The design ground water level should be selected as the maximum level duringfall conditions (before freezing) over the period equal to the expected life of theroad surfacing prior to overlaying.

In areas where the depth of frost penetration is less than the pavement thickness,the greatest seasonal groundwater level with the specified probability of beingexceeded during the period of its seasonal maximum must be taken as thedesign groundwater level.

The design groundwater level should be determined using results of short, one-time measurements and from forecasts of seasonal and long-term groundwatertable fluctuations. In the absence of such data or in case of perched water table,the level determined by the upper line of soil gleying can be taken as the designlevel.

Soils

6.5 The soils used for road construction are classified according to Appendix C,taking into account their specific function within the road structure.

6.6 Cohesive soils, which have the in-situ shear strength of less than 0.075 MPa(when tested using shear vane) are referred to as soft soils.

In instances when soil strength test data are not available, peat and soilscontaining peat, mud, clayey soils with moisture content over 0.5, wet salty soilsshould be considered as soft soils.

6.7 Soils with permeability not less than 0.5 m/day at maximum standard densityshould be considered as free-draining soils.

6.8 Assessment of stability and deformations of the roadbed must be carried out onthe basis of geotechnical engineering principles utilizing strength and deformationparameters.

Mechanical characteristics should preferably be determined for soils with intactin-situ structure, design density and moisture content.

Active subgrade layer

6.9 Active subgrade layer is the upper part of the roadbed from the lowest elevationof the pavement structure to 2/3 of the frost penetration depth but not less than1.5 m from the pavement surface.

To provide the necessary resistance and stability of the active subgrade layer, theminimum rise of the pavement surface above the design groundwater level, orabove the earth surface at locations where surface run-off is inhibited, must beselected according to Table 24.


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Table 24

Minimum pavement elevation above ground water

Soil of the active subgrade layerMinimum rise of the pavement surface, m

by climatic zonesIB IIA IIB III

Fine sand, lightweight sandy loam 1.1 0.9 0.75 0.50.9 0.7 0.55 0.3

Silty sand, silty sandy loam1.5 1.2 1.1 0.81.2 1.0 0.8 0.5

Lightweight loam, heavy loam, clays2.2 1.8 1.5 1.1

1.6 1.4 1.1 0.8

Heavy silty sandy loam, lightweight siltyloam, heavy silty loam

2.4 2.1 1.8 1.21.8 1.5 1.3 0.8

Note:1. Above the dash: rise of the pavement surface above the groundwater table, perched water table or

standing surface water level (for more than 30 days); under the dash:rise of the pavement surface abovethe earth surface at locations where surface run-off is inhibited or above standing surface water level (forless than 30 days).

2. In permanently irrigated regions the rise of the pavement surface above the winter and spring ground waterlevels should by increased by 0.4 m for climatic zones III and by 0.2 m for the climatic zone II.6.10 Soils f elevated moisture content (Appendix C, Table C7) and type I and II

coarse-fragmented hydrolabile soils (Appendix C, Table C6) should not be usedin the active subgrade layer without detailed technical analysis.

6.11 If is impossible or impractical to use non-frost-susceptible or weakly frost-susceptible soils (Appendix C, Table C8 & C9), special measures for ensuringstrength and stability of the active subgrade layer or pavement strengtheningshould be provided.

Embankments

6.12 Embankment parameters should be determined taking into account the bearingcapacity of the foundation. Foundations are subdivided into strong and weak ifthey consist of compressible and non-compressible soils respectively. Afoundation soil is considered to be weak if within the zone of embankmentinfluence there soft layers greater than 0.5 m thick.

The zone of the embankment influence should be determined by analysis orapproximately taken to be as equal to the embankment width at the foundationlevel. Natural foundations containing clayey soils with relative compression morethan 0.01 should be classified as weak.

6.13 Soils of normal moisture content and environmentally safe industrial wastesretaining strength over time and under the influence of weather and climatic

factors can be used for embankment construction without limitations.Soils, as well as industrial wastes that change strength and stability over time ordue to weather and climatic factors can be used for embankment constructionwhen stabilization measures are feasible.

6.14 Embankment height for roads passing through open terrain must be selected toprovide protection of the roadway against drifting snow.

The rise of the pavement edge above the expected level of the snow cover mustbe adopted not less than:

multi-lane highways excluding roads of category II 1.2 m

Category II 0.7 mCategory III 0.6 m


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Category IV 0.5 m

low volume roads 0.2m-0.4m

6.15 Embankments and dikes near and at approach to medium and large bridges aswell as embankments across flood plains should be not less than 0.5 m higher,and the top edge offlood protection structures and berms not less than by 0.25 mhigher, than the design water horizon, taking into account the wave height.

6.16 Degree of compaction for sandy, loessy and clayey soils in embankments shouldbe specified in terms of a compaction factor reflecting a fraction (or percentage)of standard maximum density and selected according to Table 25.

Table 25

Minimum soil compaction coefficient

Roadbed elements

Depth ofthe layerfrom the

pavement

surface,cm

Minimum soil compaction factor for types ofpavement structures

High Intermediate and lowBy climatic zones

I II III I II III

Active subgrade layer 600

95/9395

9598

9595

9393

9595

9090

Part of the embankmentaffected by flooding

150-600>600

96/9596

98/9598

95/98 95/9395

9595

9595

Active subgrade layerbelow seasonal frost line ina cut


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6.24 Cuts over 2 m deep excavated in fine and silty sands or in wet silty clays(moisture content in excess of 0.3) as well as in easily weathered or fracturedrocks should be designed with serrated slopes. As a rule, the width of serrationsshould be 1 m for less than 12 m high slopes in fine and silty sands and 2 m forrock slopes less than 16 m high.

Drainage facilities6.25 The roadbed must be protected against water infiltration and erosion by means of

a drainage system designed to collect and remove surface runoff (roadsidechannels, flumes, chutes, evaporation basins', discharge wells, etc).

The probability of exceeding design discharge of a drainage system should beadopted according to Table 29.

Table 29

Probabilities exceeding design discharge through drainage structures

Class of the road

Probability of exceeding the designdischarges in one year

Roadside andintercepting drains

Other water diversionditches

Expressway 2 3Regional road 3 5Local road 5 10

6.26 Roadside drainage channels should be provided on both sides of the roadbedexcept in instances when transverse terrain gradients and embankment heightsassure natural surface runoff.

6.27 Maximum gradient of the drainage channels should be selected based onadmissible flow rates that depend on the soil type and adopted erosion protectionmeasures for channel bottom and slopes. Roadside channels should have alongitudinal gradient not less than 5% and, in exceptional cases not less than 3%. Chutes should be provided in areas of steep gradients and grade controlstructures can be used to allow milder slopes elsewhere.

6.28 Water from roadside channels should be diverted, when their design capacity isreached. In instances when it is not possible to divert water into natural channelsand areas with lower elevation, roadside ditches should be enlarged or a parallelauxiliary diversion channel should be provided.

6.29 Slopes of drainage channels should be protected to ensure their local stabilitytaking into account constructional details of the roadbed, properties of soils,

weather and climatic factors and water flow regimes.6.30 The fill slopes affected by flooding shall be protected from waves with the

appropriate type of pitching works using concrete, reinforced concrete or asphaltconcrete industrial products or monolithic slabs depending on the hydrologicalregime of the river or basin.

When embankment is constructed by hydraulic filling, instead of stabilization,slopes can be flattened to values given in the Table 30.

Table 30

Allowable slope for embankments constructed by hydraulic filling

Soil of the fillslope

Embankment slope at the non-incoming wave height of0.1 0.2 0.3 0.4 0.5 0.6

Fine sand 1:5 1:8 1:10 1:15 1:20 1:25Light sandy loam 1:4 1:7 1:10 1:15 1:20 1:20


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Roadbed in difficult conditions

6.31 To assure stability, embankments over 12 m high, as a rule, should beconstructed using separate levels laterally supported by berms.

6.32 Roadbed and dam slopes on the water side should be design assuming rapiddrawdown and lack of drainage from the roadbed or dam body.

6.33 Estimation of general and local stability of the slopes shall be given for thecuttings made under complicated conditions and measures to provide theirstability shall be taken (appropriate cross-section, drain systems, protectivecourses, slope protection, etc).

6.34 Cuts should be used terrain with favorable soil and hydrologic conditions inrelation to freezing (rock or gravelly soils) and in the absence of ice lenses andice intercalations.

If cuts are unavoidable in difficult ground-freezing and hydrologic conditions(strata of different structure and condition, varying elevations of water-bearinghorizons, frost-related strength degradation, highly compressible soils), the

following measures should be provided:

Insulation of slopes, geotextile layers, replacement of wet silty clays with granularor other good quality materials, frost protection layers at the base of thepavement structure, provision of reliable drainage from the cut.

Shallow cuts should be completed open or finished for embankments.

6.35 A complex of slope stabilization measures may be necessary to improve stabilityof the roadbed and the slope (drainage structures, surface drainage, retainingstructures, slope grading, etc.)

6.36 The following requirements should be satisfies for embankments constructed onweak foundations:

there should be no lateral flow of foundation soil at the embankment baseduring construction and in service condition;

primary settlement should be completed prior to placing rigid pavement layers;

Note: Primary settlement is considered to be completed if not less than 90% ofthe design ultimate settlement has been completed.

6.37 Roadbed design on marshes should be based on technical and economicassessment of alternatives that must consider a possibility of removing marshysoils (including by blasting) or their utilization as an embankment base, takingspecial measures, when necessary, to ensure stability by reducing andaccelerating settlement.

In case of designs using peat removal, the required volume of soil for theembankment should be specified taking into account compensation for lateraldeformations of walls of the peat removal trench determined by calculation.

Submerged lower part of embankments installed on marshes, as a rule, shouldbe constructed using draining soils. The thickness of the draining soil layer shouldbe selected taking into account settlement in such a way that the elevation of thedraining layer is not less than 0.5 m higher than the marsh surface.

If marshy soils are used for construction of the embankment base, requirementsof Par. 6.36 for embankments on weak foundations, should be met along with thegeneral requirements for roadbeds.


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To reduce traffic-induced elastic vibrations of the embankment on peatfoundation, its height should be not less than the allowable value for a given typeof road surfacing (Table 31).

Table 31

Allowable embankment height to prevent traffic-induced vibrations

Initial thickness ofweak layer

Minimum height of embankment for different pavement structuresto prevent unacceptable elastic vibrations

High Intermediate Low2 2.5 2.0 1.54 3.0 2.5 2.06 4.0 3.5 3.0


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the first method to raise the upper permafrost horizon not lower than theembankment base and to maintain it at that level during the entire period ofthe road operation (the foundation soil is considered to be in frozencondition);

the second method - to permit thawing of the embankment base soil during

the road service period allowing permissible settlement of the pavement (thefoundation soil is thawed condition to some depth).

The first method is to be followed when the roadbed is constructed in the areas oflow-temperature permafrost comprised of highly compressible soils and clayeysoils at moisture content over the liquid limit when thawed. This method shouldbe adopted when foundation soils can be maintained in frozen condition at aneconomically justifiable cost.

If design according to the first method is selected, the location of the upperpermafrost horizon within the embankment base should be controlled by selectingan appropriate embankment height using traditional road construction materialsas well as utilizing special layers of insulating materials (peat, foam plastic, slag,

etc.) in the base.

When embankment is designed according to the second method, its heightshould be determined from thermo-mechanical calculations of total settlement,including settlement of the embankment base and of compressible embankmentlayers, not to exceed the allowable settlement of Table 32.

6.42 Depending on the topography, hydrological and ground freezing conditions, thesurface and above-permafrost ground waters must be drained from the roadthrough water diversion channels, permafrost catch ridges and drainage berms.

6.43 The roadbed structure constructed in drifting sand (Appendix C, Table C15)should be designed to minimize sand loss and accumulation due to wind action.

On overgrown or sparsely overgrown sands, 0.5 m high embankments shouldprimarily be constructed from local borrows 0.2 m deep. Higher embankmentsshould be constructed using sand from the cuts or borrow pits. Cuts excavated inuncovered and sparsely grown dune sands shall have slopes that provideprotection from drifting. To provide protection against sand loss and accu-mulation, leveled strips 15 to 40 m wide on each side of the road should beprovided and shifting landforms be fixed over a width of 200 m beyond the right-of-way. Roadbed construction in overgrown sands should be carried out withminimum disturbance of the flora and natural contours of the adjacent terrain.

Table 32

Allowable settlement of embankment and compressible embankment layers

Pavement structure type andconstruction conditions

Required thickness of stable embankment layers forexpected in-service settlement of the subgrade and of

compressible embankment layers, m0.5 1.0 1.5 2.0

High pavement Continuouslyplaced reinforced concreteslabs

2 4 6 10

Asphalt concrete pavementconstructed the same yearas the roadbed

4 8 12 20

Intermediate pavement 6 12 18 30Low pavements 8 16 24 40


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6.44 Landslide protection structures directly supporting earth pressure (retaining wallson piled foundation, cantilever sheetpile walls, anchored sheetpile walls andcombined structures) should be designed both to withstand landslide pressureindividually as well as to provide stability to a combined "slope-road structure"system.

7. PAVEMENT STRUCTURE7.1 Pavements must be designed to support traffic operations at selected design

speed, level of safety and ride comfortover the specified design life and reliabilitylevel.

7.2 In general, pavements consist of structural' layers that' include' surfacing, baseand subbase layers).

7.3 The pavement structure and the surfacing type must correspond to the functionalclassification of the road, taking into account traffic volume, traffic composition,climatic and hydrologic conditions of the area, and environmental requirements.

Pavement classification

7.4 Pavement structural types include three main categories: high, intermediate andlow.

High-type pavements include structural layers and surfacing made of cementconcrete and asphalt concrete.

Intermediate-type pavements include surfacing made of asphalt concrete andbinder-stabilized aggregate and soils.

Low-type pavements include surfacing made of binder-stabilized aggregateand soils as well as unstabilized aggregate and gravel.

7.5 According to response to traffic load and reaction to environmental factors

pavements are subdivided into rigid and flexible.Rigid pavements include structural systems consisting of cement concretesurfacing or cement concrete base and asphalt concrete surfacing.

Flexible pavements include structural systems consisting of asphalt concretelayers; aggregate and soil layers stabilized with organic and organic binders aswell as unstabilized aggregate and gravel layers.

Performance requirements for pavement surfacing

7.6 To support safe and comfortable traffic operations at design speed, pavementsurfacing must have stable properties characterized by adequate surfaceroughness and necessary skid resistance.

Roughness and skid resistance requirements for newly constructed pavementsprior to opening the road to traffic are given in the Table 33.


7.7 The total pavement thickness and thicknesses of individual layers should bedetermined in the course of pavement structural design and must ensureadequate strength and frost resistance of the entire structure


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Table 33

Roughness and skid resistance requirements for pavement surfacing

Standard test

Performance requirementAll roads except roads of

category IV and low volume

roads

Roads of category IV

and low volume roads

Surfaceroughness ofpavements

Clearance under a3 m

Not less than 95 % ofmeasurements should bebelow 5mm and the rest

under 7mm

Not less than 90% ofmeasurements shouldbe below 10mm and

rest under 15 mmAlgebraicdifference inelevations betweentwo points spacedat 5,10 and 20m

14, 20, 25 mm 16, 25, 30 mm

Skid resistance coefficientRode conditions

Normal Difficult Dangerous0.45 0.5 0.6

Note:

The required skid resistance coefficient should be assigned depending on road conditionsas follows:

(a) Normal travel conditions: represented by straight or curved road sections withcurve radii of 1000m and over, superelevation or grade not more than 30%,involving cross section elements satisfying requirements of Table 4 and operatingat levels of service according to Table 2.

(b) Difficult travel conditions: represented by road sections with horizontal curve radiifrom 250 m to 1000 m, superelevation from 30% to 60% as well as sections withreduced roadway width (when under reconstruction) and sections that satisfyrequirements of normal conditions but operating at reduced level of service, butnot lower than level D.

(c) Dangerous travel conditions: represented by road sections with lower sightdistances and steeper grades compared to minimum values in Table 10, sectionsnear at-grade intersections as well as section that satisfy requirements of normalconditions but operating at levels of service, E or F.The lane distribution factor to determine traffic volume per lane should beassumed 1.0 for one-lane roadways; 0.5 for two and three lanes; 0.35 for fourlanes and 0.3 of six lanes.

7.8 Pavement structural design should be carried out for the projected number ofrepeated applications of the standard single axle since wheel load, selected asspecified in Par. 4.4, and cumulatively acting over the design period specified inPar. 1.13.

7.9 Cumulative effects of axle leads both higher and lower than the standard loadmust be expressed in terms of the equivalent number of applications of thestandard load using appropriate load equivalency factors.

For design purposes traffic loading on pavements should be represented by therepeated action of a single wheel single axle load characterized by a constantaverage pressure acting over an equivalent circular area of a moving or standingvehicle and by the number of repetitions of the standard load.

7.10 For multi-lane highways pavement structure of all lanes should be designed forthe same maximum standard load and the same number of repetitions of thestandard load.


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7.11 The strength of flexible pavements within traffic lanes and of stabilized shouldersshould be adequate to support multiple repetitions of short-term vehicle loads.The stabilized portion of shoulders should be designed for 1/3 of traffic volumeused for design of traffic lanes.

Design of pavements on approaches to and at public trans

highway design standard (cnr 32-01-07)

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