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Red and Purple Modernization (RPM) Phase One Issued for Execution
Design-Build
PART 4 - TECHNICAL REQUIREMENTS
TABLE OF CONTENTS PAGE
December 12, 2018
4.4.3.5 City of Chicago Signs
CDOT Division of Electrical Operations (DEO) and City of Chicago Office of
4.4.3.6 Emergency Management and Communication (OEMC) Facilities
4.4.4 Design Constraints 61
4.4.5 Design Criteria 62
4.4.5.1 Site Earthwork
4.4.5.2 At Grade CTA Right-of-Way Surface Improvements
4.4.5.3 Fencing
4.4.5.4 Facility Protection Measures
4.4.5.5 Pavement Marking and Signage
4.4.5.6 Facility Utility Services
4.4.5.7 CTA Lighting Requirements
4.4.5.8 Functional Landscape and Streetscape
4.5 Drainage Systems 70
4.5.1 General Requirements 70
4.5.2 Standards, Codes, and References 70
4.5.3 Compliance Requirements 71
4.5.3.1 Stormwater Management
4.5.3.2 Surface Drainage – Public Street and Alleys
4.5.4 Design Constraints 79
4.5.5 Design Criteria 79
4.5.5.1 Closed Deck Drainage System
4.5.5.2 At-Grade CTA Property
4.5.5.3 Structural Subsurface Drainage
4.5.5.4 Temporary Drainage
4.5.6 Stormwater Management Report 86
4.5.6.1 Concept Report
4.5.6.2 Pre-Final Report
4.5.6.3 Final Reports
4.5.6.4 Conformed Report
4.5.7 Special Submittals 89
4.6 Right-of-Way Structures 90
4.6.1 General 90
4.6.2 Standards, Codes, and References 90
4.6.2.1 Track Structures
4.6.2.2 Miscellaneous Structures
4.6.3 Compliance 93
4.6.4 Design Constraints 93
Red and Purple Modernization (RPM) Phase One Issued for Execution
Design-Build
PART 4 - TECHNICAL REQUIREMENTS
TABLE OF CONTENTS PAGE
December 12, 2018
4.6.4.1 Service Life
4.6.4.2 Clearances and Envelopes
4.6.4.3 Design Methodology
4.6.4.4 Vibration
4.6.4.5 Fatigue
4.6.4.6 Fracture Control
4.6.4.7 Stability
4.6.4.8 Serviceability
4.6.4.9 Displacements and Tolerances
4.6.4.10 Track Structure Loading
4.6.4.11 Evaluation of Existing Elevated Track Structures
4.6.4.12 Retaining Walls Loading
4.6.4.13 Miscellaneous Structures Loading
4.6.4.14 Temporary Structures Loading
4.6.5 Design Criteria 116
4.6.5.1 Elevated Track Structures
4.6.5.2 Existing Elevated Track Structure at RPB
4.6.5.3 Existing Elevated Track Structure at Montrose Avenue
4.6.5.4 Retaining Walls
4.6.5.5 Miscellaneous Structures
4.6.5.6 Temporary Structures
4.6.6 Material and Construction Criteria 144
4.6.6.1 General
4.6.6.2 Reinforced Concrete
4.6.6.3 Joint Seals for Bridge Deck Joints
4.6.6.4 Drilled Shafts
4.6.6.5 Structural Steel
4.6.6.6 Steel for Casings and Piles
4.6.6.7 Dissimilar Materials
4.6.6.8 Electrical Isolation Materials
4.6.7 Design Submittals 152
4.6.7.1 Structure Design Submittals
4.6.7.2 Structural Assessment Report
4.6.7.3 Special Submittals
4.7 Station Structures 156
4.7.1 General 156
4.7.2 Standards, Codes, and References 156
4.7.3 Compliance Requirements 158
4.7.4 Design Constraints 159
RPM Phase One – Design-Build Issued for Execution2014-0017.06 December 12, 2018
PART 4.6 – Right-of-Way Structures 90
4.6 Right-of-Way Structures
4.6.1 General
This Part defines the technical requirements for the Permanent and Temporary structural
work necessary to complete the right-of-way structures that consist of track structures and
miscellaneous structures for this Project. Track structures are structures that support CTA
transit tracks; and these structures include, but are not limited to, elevated track structures,
bridges, retaining walls and underground structures. Structures requiring a City of Chicago
Department of Building Permit are covered in Part 4.7, Station Structures.
These requirements will govern the analysis, design and construction of track structures and
all other miscellaneous structures not covered under Part 4.7 Station Structures, which are
part of the CTA system. These other Miscellaneous Structures are auxiliary to or support the
system; and all load carrying elements will be engineered to the requirements stated herein.
These requirements are intended to provide uniformity in the design and standardization of
the materials used.
4.6.2 Standards, Codes, and References
The following is a list of publications that will be used for all design and construction related
to Part 4.6.
4.6.2.1 Track Structures
A. Specific obligations and design criteria identified in Part 4.6
B. AREMA Manual for Railway Engineering
C. AASHTO LRFD Bridge Design Specifications, 7th Edition with 2015 and 2016
Interim Revisions. This Standard applies to the elevated track Red-Purple
Bypass structure only, unless otherwise noted in Part 4.6.
D. CTA Adjacent Construction Manual
E. FHWA Micropile Design and Construction Guidelines, FHWA/NHI-05-039
F. FHWA Geotechnical Engineering Circular No. 4-Ground Anchors and Anchored
Systems FHWA-IF-99-015
G. FHWA Tiebacks FHWA RD-82-046 and FHWA RD- 82-047
H. AASHTO Manual for Bridge Evaluation, 2nd Edition, with 2011, 2013, 2014 and
2015 Interim Revisions.
I. AASHTO Guide Design Specifications for Bridge Temporary Works, 2nd Edition.
J. AASHTO Construction Handbook for Bridge Temporary Works, 2nd Edition.
K. AASHTO LRFD Bridge Construction Specifications 3rd Edition with interim
revisions. This Standard applies to the elevated track Red-Purple Bypass
structure only.
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PART 4.6 – Right-of-Way Structures 91
L. AASHTO/AWS D1.5M/D1.5: 2015 Bridge Welding Code, 7th Edition
M. ACI 318, Building Code Requirements for Structural Concrete
N. PCA Guide Specification for High Performance Concrete for Bridges, 1st Edition.
O. ACI 315, Details and Detailing of Concrete Reinforcement
P. IDOT Bureau of Bridges and Structures Bridge Manual, January 2012
Q. IDOT Bureau of Design and Environment Manual, September 2010
R. IDOT Bureau of Construction Manual, January 2006
4.6.2.2 Miscellaneous Structures
A. Specific obligations and design criteria identified in Part 4.6
B. AREMA Manual for Railway Engineering
C. ASCE 7, American Society of Civil Engineers Minimum Design Loads for Building
and Other Structures
D. Chicago Building Code (CBC)
E. CTA Adjacent Construction Manual
S. ACI 318, Building Code Requirements for Structural Concrete
F. International Building Code (IBC), 2009
G. AASHTO Guide Design Specifications for Bridge Temporary Works, 2nd Edition.
H. AASHTO Construction Handbook for Bridge Temporary Works, 2nd Edition.
I. PCA Guide Specification for High Performance Concrete for Bridges, 1st Edition.
J. ACI 315, Details and Detailing of Concrete Reinforcement
K. AWS/ANSI D1.1/D1.1M:2015 Structural Welding Code, 23th Edition
L. AASHTO Standard Specification for Structural Supports for Highway Signs,
Luminaires, and Traffic Signals, 6th Edition, with 2015 Interim Revisions
M. ANSI/AISC 360-10, Specification for Structural Steel Buildings
N. National Electrical Manufacturers Association (NEMA) Standards Publication VE
1
O. Private utilities approved CTA standards as required.
In the following table, the letter “C” indicates the portions of the applicable Guidance
Specifications that are contractual requirements and the “R” indicates the portions of the
specifications that are for reference.
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PART 4.6 – Right-of-Way Structures 92
Table 4.6-1: GUIDANCE SPECIFICATIONS
Part 1 Part 2 Part 3 Spec.
No.Specification
General Products Execution
02 83 00 CONTAINMENT AND DISPOSAL OF
LEAD PAINT CLEANING RESIDUES -
BRIDGE STRUCTURES
C R R
03 20 10 CONCRETE REINFORCEMENT
EPOXY COATED
C C C
03 20 20 CONCRETE REINFORCEMENT
PLAIN STEEL
C C C
03 30 00 CAST-IN-PLACE CONCRETE C C C
03 30 15 HIGH PERFORMANCE CONCRETE C C C
03 40 00 PRECAST STRUCTURAL
CONCRETE
C C R
03 60 00 GROUTING R C R
03 61 11 NON-SHRINK GROUT R C R
03 63 00 EPOXY GROUTING OF DOWELS R C C
03 64 23 EPOXY INJECTION GROUTING R C R
03 74 00 CONCRETE REPAIRS C C C
05 10 30 STRUCTURAL STEEL FOR TRACK
AND PLATFORM STRUCTURE
C C C
05 80 00 EXPANSION SLIDE ASSEMBLIES,
SLIDE BEARING ASSEMBLIES,
BEARING PADS, AND ISOLATION
PADS
C C R
05 80 40 HIGH LOAD MULTI-ROTATIONAL
BEARINGS
C C C
07 95 63 BRIDGE EXPANSION JOINTS C C C
09 90 00 PAINTING C C C
09 91 02 CLEANING AND PROTECTIVE
COATINGS OF EXISTING BRIDGES
C C C
09 97 23 CONCRETE SEALER R C R
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PART 4.6 – Right-of-Way Structures 93
Table 4.6-1: GUIDANCE SPECIFICATIONS
31 09 13 GEOTECHNICAL AND STRUCTURAL
INSTRUMENTATION AND
MONITORING
C C C
31 15 00 STRUCTURAL SHORING C C C
31 23 00 CONTROLLED LOW-STRENGTH
MATERIAL
R C R
31 50 00 EXCAVATION SUPPORT AND
PROTECTION
C C C
31 63 29 DRILLED CONCRETE PIERS AND
SHAFTS
C C C
31 63 33 DRILLED MICROPILES C C C
4.6.3 Compliance
Contractor’s work will comply with all applicable municipal, county, state and federal
regulations and codes including requirements of the City of Chicago’s Department of
Transportation, Division of Infrastructure Management, Office of Underground Coordination.
When proposed structures are located within influence zones of property owned by other
agencies or owners other than the CTA, including buildings, Contractor will adhere to all
municipal, county, state and federal requirements.
4.6.4 Design Constraints
4.6.4.1 Service Life
Contractor will analyze, design and construct all new Permanent track structures,
miscellaneous structures and other structures to achieve the required service life. All
Permanent elements and all existing structural elements whose load carrying capacities
are altered by the work, will be analyzed and designed to conform to the requirements of
the RFP and the codes and standards.
Contractor will develop an overall approach and strategy to ensure the durability and
required service life of 100 years for critical structure elements, including the following:
A. Concrete Superstructure
B. Steel Superstructure and Connections
C. Steel Columns, Bents and Connections
D. Concrete Substructure
E. Foundations
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PART 4.6 – Right-of-Way Structures 94
F. Retaining Walls
Contractor will develop Service Life Report as a Design Submittal that clearly
demonstrates how the recommended materials and methods will provide the required
service life for the elements listed. The report will address the detrimental effects on all
new Permanent structure elements and all existing structural elements whose load
carrying capacities are altered by the work. The report will include, but not be limited to,
steel and concrete elements; and at a minimum, the adverse effects of weather, freeze
thaw cycles, movement, permeability, chloride exposure, cracking, corrosion rates,
carbonation and alkali-aggregate reaction will be included in the testing, analysis and
recommendations portions of the report to achieve the required service life in the
completed Project.
The report will be prepared using Good Industry Practice and be based on a
probabilistic, deterministic, and/or empirical approach unless otherwise specified in the
Technical Requirements. The report will provide the design and construction
requirements for: a 100-year life for all new elements listed above; and the service life
for the elements listed in Table 4.6-2: Service Life.
Service Life analysis of all new concrete elements will be based on the probabilistic
method only with mean service life equal to or better than the required service life, and
will avoid unintended maintenance within the service life required by these technical
provisions. Unintended maintenance for new concrete is defined as any concrete repair
of the surface area of the concrete element, due to deterioration, within the first 60 years
of service life and repair of greater than 2.5 percent of the concrete surface area every
10 years for the remainder of the required service life. Where service life strategy
includes the use of concrete sealers, the sealer will only be considered effective for the
initial application and further application cycles will not be considered.
All materials to be used, including means and methods, will be included in the report. To
provide the required service life, various materials, methods and combinations thereof
will be fully described and detailed.
All recommended materials and methods will be fully investigated and studied to confirm
that their use will not create any detrimental effects (i.e. electric current flow, galvanic
corrosion, etc.) within the completed Project or existing structures.
The following elements are to be designed for an elemental service life that meets or
exceeds that shown in the table below. These elements may require replacement or
retrofit at a future time within the 100-year service life of the critical track structure
elements.
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PART 4.6 – Right-of-Way Structures 95
Table 4.6-2: SERVICE LIFE
ELEMENT SERVICE LIFE
Deck Joints 25 years
Deck Joint Hardware – including but not limited to strip seal
extrusions and modular joint components
50 years
Fixed Bridge Bearings 75 years
Expansion Bearings – Elastomeric- Types I and II 50 years
High Load Multi-Rotational (HLMR) Disc Bearings – Disc and
sliding surfaces
50 years
Existing Retaining Wall Rehabilitation and Repairs 25 years
Structural Rehabilitation of Existing Elevated Track Structure,
Elements and Connections:
High Performance Paint system and time to first maintenance for
same:
50 years
25 years
Elements with a service life of less than 100 years will be detailed to allow for future
rehabilitation/replacement work to be completed through a method that takes no more
than one track out of service at a time. Rehabilitation/replacement plans will be included
as part of the Final Design Submittal for any Design or Work Package to demonstrate
how the future work will be performed during staged construction.
4.6.4.2 Clearances and Envelopes
For all track, street, alley and general clearances, see Part 3 of the RFP.
4.6.4.3 Design Methodology
Contractor will design the new and rehabilitated track and miscellaneous structures in
accordance with the applicable loads, load combinations and requirements specified
herein. For Service Load Design, an increase in allowable stresses for Temporary
structures, or for Permanent structures withstanding Temporary loads, will not be
allowed.
Steel elements, except portions of the Red-Purple Bypass structure, will be designed in
accordance with the codes and standards utilizing Service Load Design (SLD)
methodology.
Timber, wood or fiberglass elements will be design in accordance with the codes and
standards utilizing Service Load Design (SLD) methodology.
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PART 4.6 – Right-of-Way Structures 96
Concrete elements, except portions of the Red-Purple Bypass structure, will be designed
in accordance with the codes and standards utilizing Load Factor Design (LFD)
methodology.
Foundation elements, except portions of the Red-Purple Bypass structure, will be
designed in accordance with the codes and standards utilizing Service Load Design
(SLD) methodology. Allowable soil bearing pressures will be used for the design of
shallow foundation elements.
4.6.4.3.1 Red-Purple Bypass Structure (NM5)
Horizontally curved and tangent structures, from approximately station 802+43 to
814+94 as shown on sheets ST-1107 thru ST-1110 of the Base Case Plans, will be
designed in accordance with the Load and Resistance Factor Design (LRFD) method
as defined in the AASHTO documents listed in the codes and standards Sub Part
4.6.2. For all elements of the steel superstructure, the following list of articles in
Table 4.6-3 from the AREMA Manual will be used as the governing criteria unless
the AASHTO LRFD document is more stringent.
Table 4.6-3: AREMA MANUAL CHAPTER 15 ARTICLES
a. 1.5.1 Slenderness Ratio g. 1.10.4 Welded Attachments
b. 1.5.4 Thickness of Material h. 1.11.2 Lateral Bracing
c. 1.5.9 Connections and Splices i. 1.11.4 thru 1.11.6 Bracing
d. 1.6 Members Stressed Primarily in
Axial Tension or Compression
j. 1.13.6 Uplift
e. 1.7.1 thru 1.7.9.2 Members
Stressed Primarily in Bending
k. 1.14 Fracture Critical Members
f. 1.10.2 Prohibited Types of Joints
and Welds
4.6.4.4 Vibration
Elevated track structures will be designed to limit dynamic interaction and avoid
resonance from its interaction with train live loads. In order to satisfy this requirement,
the elevated track structure's fundamental first mode of vertical vibration, considering
only dead loads, will be greater than:
A. 2.5 cycles per second - For longitudinal members of simple spans
B. 3.0 cycles per second - For longitudinal members of continuous spans
At a minimum, any elevated track structure with a fundamental first mode of vertical
vibration under 6.0 cycles per second will require a specific Vehicle-Structure
Interaction (VSI) Study to be prepared and submitted by Contractor for review by the
CTA as a Design Submittal. The study will provide background, detailed evaluation, and
RPM Phase One – Design-Build Issued for Execution2014-0017.06 December 12, 2018
PART 4.6 – Right-of-Way Structures 97
conclusions, which demonstrate that resonance is not induced in the track structure as
a result of its intended use.
4.6.4.5 Fatigue
Fatigue analysis of all track structures will be performed in accordance with AREMA
Manual only, assuming all structural components are subject to over 2,000,000 stress
cycles. Mean impact load is not allowed; 100 percent of the impact load from the
passenger rail car loading will be used. The Load on Axles for Fatigue and Deflection
Analysis shown in Figure 4.6.4 will be used for fatigue analysis.
4.6.4.6 Fracture Control
Fracture Critical Members (FCM) and their components will follow the requirements in
the codes and standards, except as modified herein.
The following members will be considered fracture critical and subject to full
implementation of the Fracture Control Plan requirements:
A. Steel cross girders supporting simple or continuous stringers
B. Steel box cross girder at Bent 13P of the Red-Purple Bypass
C. Steel columns with tension stresses from any load combination
D. Steel stringers for open deck structure
The above list of steel elements are the only acceptable FCMs for the Project.
Contractor will prepare and submit as a Design Submittal a Fracture Control Plan that
includes all of the requirements of the codes and standards along with any additional
measures that Contractor deems necessary to address fracture of the track structures
and their members.
4.6.4.7 Stability
In calculating the stability of stringers and bents, the live load on one track will be 800 plf
without impact. On multiple-track elevated structures, this live load will be on the leeward
track with respect to wind direction. For structures with curved track, the centrifugal and
live loads will be applied. The minimum factor of safety against overturning will be 1.50.
4.6.4.8 Serviceability
Live load deflection design checks will be based on the live load that can simultaneously
occur on the structure including but not limited to the Rail Vehicle – Passenger Car
(including impact) acting simultaneously with footwalk live load and positioned for worst
effect. In any event, live load deflection will not exceed 1/640 of the span length center-
to-center of bearings. The live load deflection limitations presented above are in addition
to any more restrictive live load deflection criteria deemed necessary by the Lead
Structural Bridge Designer in order to complete the design.
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PART 4.6 – Right-of-Way Structures 98
In addition to the deflection and other serviceability requirements in the codes and
standards, the following criteria will be used for the design of the elevated track
structures.
The following minimum serviceability criteria will also be satisfied in addition to any other
more stringent requirements deemed necessary by the Lead Bridge Structural Designer;
A. Differential vertical settlement (long-term) will be limited to a value that does not
affect normal operations of the trains and will not cause a gradient in the rail
profile that exceeds 1/2400 of the sum of the lengths of any two adjacent spans.
The vertical settlement (long-term) will be limited to (when the values of L1 and
L2 are in inches):
1.5 inch∆ <(�1 + �2)
2400 <
B. The differential vertical settlement (long-term) between adjacent substructure
units of the elevated track structures will be limited to (when the value of L is the
length of the shorter span is in inches):
1 inch∆ <
�1200 <
C. The maximum relative rotation at expansion joints about a transverse axis for the
bents and substructure of the elevated track structures will be limited to:
(use only Load Combination SLD IV)� < 0.005������
Figure 4.6.1
D. The maximum relative rotation at expansion joints about a vertical axis for the
bents and substructure of the elevated track structures will be limited to:� < 0.0015������ (use only Load Combination SLD III)
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PART 4.6 – Right-of-Way Structures 99
Figure 4.6.2
The increase in rail stress due to longitudinal deflection will be limited to 20 ksi
(Determine actual force in rail using conditions contained in only Load Combination
SLD IV. Consider worst case service temperature regime which can occur
simultaneously in the structure and rail. Ignore increase in allowable unit stress for
purposes of rail stress limit)
Figure 4.6.3
4.6.4.9 Displacements and Tolerances
The control of all deformations and displacements through proper design and
construction is of paramount importance in obtaining an acceptable ride quality for the
transit trains. Contractor will design and construct all Temporary and Permanent
structures to include the effects of all displacements (dead load deflections, etc.) and
tolerances that will affect the final elevation and location of the completed track
structures and running rails. These displacements and tolerances may be due to, but not
limited to, loads on Temporary or Permanent structures, settlements, fit-up, design
changes, field conditions and as-built elevations of the substructure or superstructure
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PART 4.6 – Right-of-Way Structures 100
components.
4.6.4.10 Track Structure Loading
The weights, unit weights, loads and forces provided in this Sub Part are the minimums
required for the Project. Lead Bridge Structural Designer will be responsible for
determining the actual weights, loads and forces for all of the proposed elements prior to
starting the design. Where loads from platforms, stations or other structures are
supported by the track structures, the loads on the other structures will be determined
according to the applicable code or standard; and the loading will be transferred to the
track structure and carried thru the track structure design according to the requirements
of Part 4.6.
The forces, displacements and overall effects from the proposed structures and systems
will not be transferred into the existing adjacent structures. The track structures will be
designed for the maximum loads and forces to which they will be subjected, including
erection loads occurring during construction and the following other loads and forces:
4.6.4.10.1 Dead Loads (DL)
A. Unit Weight of Materials: The design weights of materials will be as listed in
the AREMA manual. The unit weight used for timber ties and guard ties will
be 65 lbs./ft3. For those materials not listed, the best available technical
information will be used and its source or reference shown or provided in
calculations.
B. Track Equipment: Other railway appendages (signal, electrical, mechanical,
etc.) supported by the structure will be considered as part of the track. Their
loads will be investigated and included.
C. Open Deck Track: For the design of new structures and rehabilitation of
existing structures, the minimum track loads are shown in Table 4.6-4 Track
Loads. Track loads will be the governing of the minimum in Table 4.6-4 or
actual track system designed and installed. The actual track system will be
verified with the designer of the track to determine the adequacy of the loads
shown.
Table 4.6-4: TRACK LOADS
Track Type Weight of Track System
(lbs. / ft. / track)
Straight Track 460
Curved Track without Restraining Rail 500
Curved Track with Restraining Rail 570
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PART 4.6 – Right-of-Way Structures 101
Loads shown in Table 4.6-4 include running rails, guard rails
(SIGs), contact rail, third rail chairs, spikes, plates, clips and ties
but do not include track footwalk with guardrails and equipment.
D. Closed Deck Structures: The density of structural concrete slabs, plinths and
concrete toppings (second pour) will be 150 lbs./ft3 which includes steel
reinforcement.
E. Ballasted Deck: Use track loads in Table 4.6-4 Track Loads. Structures
supporting ballasted track will be designed to carry 6 in. of ballast in addition
to that required for initial construction to allow for future adjustment of track
profile. There will be no reduction for the volume of ties.
F. Non-Ballasted Closed Deck (Direct Fixation): Loads in Table 4.6-4 Track
Loads will be adjusted for direct fixation track work based on the
manufacturer of specific track system. When considering non-ballasted
closed deck (direct fixation), the unit weight of the track system (per track) will
be a minimum of 300 plf.
G. Elevated Track Structures: Track Level Footwalk, Equipment Platforms, and
Railings
i. Dead Load for Center Footwalk and Cantilevered will be a minimum of 25
psf. This weight includes the tie supports for the walkway, the walkway
stringers, and the decking.
ii. Dead Load for Outside Edge Railings will be a minimum of 20 plf.
H. Noise Barrier: At locations warranted, actual weight of such walls supported
by track structure will be determined and used for the design.
I. Miscellaneous Loads: Any system or facility such as piping, conduits,
transformer vaults, tiebreaker houses, manholes, pulling irons, and other
services which will apply a load or force, or cause a force to be transmitted, to
the track structure will be included as part of the design loads.
4.6.4.10.2 Earth Pressure Forces (E)
Loads from adjacent structure foundations will be investigated and included, where
appropriate, in the design. Dead and live loads that can be transferred to the design
structure will be included as design loads. In the absence of actual loads for which
an adjacent structure was designed, provisions of the Chicago Building Code,
estimated weights, and the heaviest occupancy for which the structure is suitable will
be used.
Horizontal and vertical distribution of loads from foundations of existing buildings will
be determined/applied in accordance with Part 4.3 Geotechnical.
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PART 4.6 – Right-of-Way Structures 102
4.6.4.10.3 Live Loads (LL)
A. Rail Vehicle-Passenger Rail Cars: See Figure 4.6.4 for axle loading and
spacing. Any combination of train lengths and loadings, which produces the
critical design forces in the member to be designed, will be used.
Figure 4.6.4
B. Rail Vehicle-CTA Rail Crane: See Figure 4.6.5 for axle loading and spacing.
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PART 4.6 – Right-of-Way Structures 103
Figure 4.6.5
The vehicle live load used for the Project design will consider both the
passenger rail car and the CTA rail crane axle load configurations shown in
Figures 4.6.4 and 4.6.5, respectively.
Any load combination that includes the rail crane will only be used to confirm
that the loads and stresses are acceptable for the maximum rating level per
AREMA. When the rail crane loading and the passenger rail car(s) occur
simultaneously on a multi-track structure, the rail crane will occupy only one
track of the multi-track structure, while the other track(s) are occupied by the
CTA passenger rail car load. Any combination of train types (except as noted
above), lengths and loadings, which produce critical forces in the member to
be designed, will be used.
C. Footwalk Live Loads-Elevated Track Structures: The following loads will be
included:
i. New Structures - 200 psf for all footwalk, this pressure includes a
materials storage allowance.
ii. Existing Structures - 200 psf for all footwalk, this pressure includes a
materials storage allowance. However, in situations where the existing
structure cannot accommodate such loading, a reduction may be
allowed as approved by the CTA.
iii. New and Existing Structures - 3 kip point load for all footwalk, for future
scaffolding or mobile crane loads (coupled with a 30 psf construction
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PART 4.6 – Right-of-Way Structures 104
load).
D. Live Load for Track Equipment Platforms: Track equipment platforms and
their supporting structures will be designed for the actual weight of equipment
plus a 200 psf pressure applied over the areas that are free of equipment.
E. For station, platform, canopy, roof, drip pan, guardrail and handrail loads, see
Part 4.7.
F. Adjacent Structures: Live loads from adjacent structures that can be
transferred to the design structure will be investigated and included in the
design when appropriate. In the absence of the building actual design loads,
provisions of the Chicago Building Code, based on the building’s occupancy,
will be used.
G. Noise Barrier: A minimum design live load of 100 psf and a single 300 pound
point load will be used to design the noise barrier. These loads will be
considered to act simultaneously and in the same direction to produce the
worst force effect. Each distinct direction (e.g. up, down, in or out) analyzed
will be considered separately for purposes of design.
4.6.4.10.4 Impact Loads (IM)
A. Impact loads will be applied to the superstructure, and generally those
members of the structure which extend down to the foundations. The portion
of the structure, above the ground line, that includes bents or piles rigidly
connected to the superstructure (as in rigid frame or continuous member
designs) will be designed for impact loads. Impact will not be included in the
design for abutments, retaining walls, foundations, footwalk and piles except
the portion of piles (pile bents) rigidly connected to the superstructure. The
impact loads presented below represent the minimum requirements and are
in addition to any other impact loads the Lead Bridge Structural Designer
deems necessary to complete the design.
B. Minimum impact loads will be per the AREMA Manual Chapters 8 and 15 as
required for rolling equipment without hammer blow, but will be no less than
30 percent of the rail vehicle live load. A reduction for speed will not be
allowed in the design of new structures.
C. The minimum Rocking Effect (RE) from rail vehicle live loads will be a force
equal to 10 percent of the axle load applied downward on one rail and
upward on the other. The force will be applied on all tracks and the direction
of the couple will be such that the couple will produce the greatest force in the
member under consideration.
4.6.4.10.5 Centrifugal Force (CF)
Centrifugal force for elevated track structures will be applied in accordance with the
AREMA Manual using posted speed or signaled speed, whichever is higher.
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4.6.4.10.6 Rail-Structure Interaction Forces (FL, FR)
The structure will be designed to accommodate forces from continuous welded rail
(CWR), including CWR laid in tangents, horizontal and vertical curves. When
examining the temperature rise and temperature fall cases between the elevated
track structure and the rail, Contractor will examine the conceivable behavior of the
structure in these cases to determine the worst actual force effects for purposes of
completing the design.
Contractor will compute these forces from the interaction of the structure, fastener
and rail as follows:
A. Longitudinal Forces on a Tangent Structure (FL, FLM)
i. FL = Tangential interaction force due to longitudinal rail fastener restraint
computed using the normal operations fastener restraint. This force is
used in the service load design of the superstructure.
ii. FLM = Tangential interaction force due to longitudinal rail fastener restraint
computed using the malfunction condition fastener restraint. This force is
used in ultimate load design of superstructure as well as the service load
design of the substructure.
B. Radial and Tangential Restraint Forces on Curved Structure (FR, FRM)
i. FL = See longitudinal forces on a tangent structure above
ii. FR = Radial interaction force due to longitudinal rail fastener restraint
computed using the normal operations fastener restraint and extreme
temperature range.
iii. FRM = Radial interaction force due to longitudinal rail fastener restraint
computed using the malfunction condition fastener restraint and extreme
temperature range.
C. Thermal Rail Forces
Contractor will determine the movements and their effects resulting from
temperature variations between the elevated structure and the rail in
accordance with the requirements herein and the AREMA Manual. The
minimum temperature rise differential between the continuously welded rail
(CWR) and supporting elevated track structure will be 35°F and the minimum
temperature fall differential between the CWR and supporting elevated track
structures will be 45°F.
The CWR will be installed at a stress-free temperature, To. See Magnitude of
Loads below for the value of To along with the minimum and maximum
design rail temperatures.
Axial thermal stress in the rail is determined by the following equation:
fT = (E) ( ) (To - Tr)∝
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Thus the axial thermal force in the rail is equal to:
FT = (E) ( ) (To – Tr) (A)∝Definitions:
A positive rail stress or force is tensile.
A negative rail stress or force is compressive.
fT = Axial thermal rail stress
FT = Axial thermal rail force
E = Modulus of Elasticity of the rail
= Coefficient of thermal expansion of the rail ∝
Tr = Rail temperature
To = Stress-free temperature of the rail
A = Cross-sectional area of the rail
At horizontal and vertical curves, the axial force creates radial rail forces
equal to:
FT,curve=FT/R
Where:
FT,curve = Radial thermal rail force at a horizontal or vertical curve
FT = Axial thermal rail force
R = Radius of rail curvature
This radial thermal rail force, in units of force per length of rail is radially
directed towards the center of the circular curve for tension in the rail, and
radially directed away from the center of the circular curve for compression in
the rail.
All of the above equations apply if there is no motion of the rail. If rail motion
is possible, the relaxation of the rail forces will be analyzed. Locations where
rail motion reduce the thermal forces include:
Axial motion of rail at rail expansion joints;
Radial and tangential movements of rail and the supporting structures
on curved track; and,
Tangential movements of the supporting structure on tangent track.
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Magnitude of Loads
CF1 = Normal restraint per fastener as determined by Contractor
CF2 = Malfunction restraint per fastener (1.5 x CF1)
To = Design stress-free rail temperature (to be determined by Contractor)
Tr,MAX = Maximum design rail temperature (150 °F)
Tr,MIN = Minimum design rail temperature (-30 °F)
A = Cross-sectional area of rail
Contractor will use the thermal values in Sub Part 4.6.4.10.12 along with the
codes and standards to evaluate the appropriateness of these values and
adjust as needed to larger temperature ranges and larger temperature
differentials, as needed and as deemed necessary by the Lead Bridge
Structural Designer, in order to complete the design. The Lead Bridge
Structural Designer will propose a design stress-free rail temperature that
best balances the forces and risks of rail compressive stress including
buckling and other compressive failure modes at higher temperatures, and
rail tension failure modes including rail separation at lower temperatures. This
proposed design stress-free rail temperature will be derived as part of the
analysis and included in the Rail-Structure Interaction Report.
When an unbalance of rail thermal forces exists, the elevated track structure
will be designed to resist this unbalanced force. These unbalanced forces
may occur, but are not limited to, in the following conditions:
In curved transition structures due to thermal force relaxation caused
by radial deflections of the curved structures;
Where adjacent structures have non-symmetrical structural
configurations or non-symmetrical fastener longitudinal restraint
characteristics;
At rail joints;
At abutments and expansion joints.
Contractor will undertake a comprehensive non-linear analysis of rail-
structure interaction which accurately models the elasto-plastic behavior of
the direct fixation fasteners. A Rail-Structure Interaction Report which fully
describes the methodology, and includes analysis results and conclusions
which demonstrate that the criteria have been fully met and incorporated into
the design of the elevated track structure, will be prepared by Contractor and
submitted to the CTA as a Design Submittal. The report will be coordinated
and consistent with the Track Integration Plan, Sub Part 4.8.6.10, in order to
properly include the final in-place materials in the rail-structure interaction
studies and report.
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Criteria for additional stresses arising from rail-structure interaction effects
are defined in Sub Part 4.6.4.8 Serviceability.
4.6.4.10.7 Lateral Forces from Equipment (N)
The lateral forces from equipment will be determined and applied in accordance with
the AREMA Manual, Chapter 15 Article 1.3.9.
4.6.4.10.8 Water Pressure and Buoyancy (B)
Structures located below the ground water table will be designed to resist water
pressures and uplift force caused by the full range of possible ground water table
elevations. The design will take into account the effect of hydrostatic pressure
pertaining to possible construction sequences. Earth fill over structures will not be
used to resist buoyancy.
4.6.4.10.9 Wind Loads (W and WL)
Wind loads in this Sub Part will be determined per the AREMA Manual with the
following clarifications:
A. Wind Forces on elevated track structure with no train (W) will be per AREMA
Manual Chapter 15 Article 1.3.8.
B. Wind Forces on elevated track structure with train–station and non-station
Areas (W and WL) will be per AREMA Manual Chapter 15 Article 1.3.7
except that the horizontal force on train will be applied at 6 ft. above the top of
running rail. Wind forces will be applied to one track at-a-time.
4.6.4.10.10 Longitudinal Force (LF)
A. Longitudinal forces will be applied to structures in any direction that
generates the critical design load. Trains will be considered to travel in both
directions on all tracks. The trains generate 200 kips from deceleration,
including emergency braking, and 100 kips from acceleration.
i. The longitudinal forces will be distributed over a maximum of 1200 ft.
length (or as determined by design) of structure.
ii. Relative stiffness differences between bents will be accounted for in the
distribution of longitudinal forces.
B. Longitudinal force for elevated track structures will be applied in accordance
with the AREMA Manual with the following modifications:
i. New Design or Rehabilitation of Existing Elevated Track Structures
Forces are applied at 8 ft. above top of running rails.
Structures Supporting 1 to 3 Tracks.
The longitudinal forces, applied simultaneously, will be 200 kips for
one track on the track structure and 100 kips for each additional track.
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Structures Supporting 4 Tracks.
The longitudinal force, applied simultaneously, will be 200 kips for
each of two tracks on the structure and 100 kips for each additional
track on the track structure.
Structure under any track will be capable of resisting 200 kips.
ii. Longitudinal Force Due to Friction or Shear at Expansion Bearings. The
track structure will be designed in accordance with AREMA Manual,
Chapter 8 Article 2.2.3.k.
4.6.4.10.11 Shrinkage and Creep Forces (SH and CR)
The AREMA Manual and material type will be used to determine strains,
deformations, displacements and their effects due to shrinkage and creep.
4.6.4.10.12 Thermal Forces in Structure (TU and TG)
A. Temperature Uniform (TU): The track structure will be designed for the
displacements and their effects resulting from variations in temperature in
accordance with the following and the AREMA manual.
Table 4.6-5: TEMPERATURE RANGES
Concrete Steel Rail
Temperature Rise 35 oF 50 oF *
Temperature Fall 45 oF 100 oF *
Coefficient of
Thermal Expansion
0.000006 in/in/ oF 0.0000065 in/in/
oF
*
* refer to Sub Part 4.6.4.10.6 Rail Structure Interaction Forces
B. Thermal Gradient (TG): The portion of the Red-Purple Bypass structure, from
approximately station 802+43 to 814+94 as shown on sheets ST-1107 thru
ST-1110 of the Base Case Plans, will be designed for the effects resulting
from the temperature gradient within the track structure in accordance with
AASHTO’s LRFD Specifications.
4.6.4.10.13 Settlement Forces (SE)
Contractor will make provisions for the effects of the predicted settlement of the
structure over its design life. The structure will be designed to resist the forces
caused by the anticipated settlement of supports in accordance with AREMA and the
requirements of this Sub Part. (See also Sub Part 4.6.4.8 Serviceability.)
4.6.4.10.14 Earthquake (EQ)
Contractor will include the seismic loads and their effects as required by the codes
and standards.
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4.6.4.10.15 Snow and Ice Loads (IC)
Contractor will include the effects of snow and ice accumulation on the structure and
the loads will be applied to all horizontal surfaces and the horizontal projection of
sloping surfaces.
A. Closed Deck Elevated Track Structures: The snow load will be 30 psf.
B. Snow Drift: The snow drift load will be calculated per the Chicago Building
Code and ASCE 7 using 25 psf. The calculated snow drift will be combined
with the 30 psf snow load.
C. Ice Pressure: The track structure will be design for the effects of ice pressure
in accordance with the AREMA Manual, Chapter 8.
4.6.4.10.16 Vehicle Collision Force (CT)
A vehicle collision force, due to a vehicle leaving the roadway, at any elevated track
structure column (bent column) will be included in the design for the track structure.
The force will be calculated using the equation below, AASHTO LRFD Specifications
Section 3.6.5.1 and the legal posted speed limit for all structures. The applied load to
the column in a roadway or immediately adjacent to a roadway will be:
where = posted speed limit + 10mph�� = (������ ��������� �����) × ( �65)2 �
4.6.4.10.17 Rail Break Forces (RB)
A. Rail break forces (RB) are transferred to the track structure in shear by the
fasteners when a rail break occurs. The rail will slip on both sides of the rail
break until the necessary number of fasteners develops the tensile force in
the rail. The rail break force is resisted both by the track structure and the
unbroken rails on the track structure.
B. Contractor will determine the force distribution to the track structure created
by the rail break through analysis. The track structure will be designed to
include horizontal forces at the fixed bearings due to the summation of the
restraint of each rail fastener. The track structure will also be designed to
include the twisting moment in the horizontal plane at the height of the low rail
due to opposing directions of the forces in the broken and unbroken rails.
C. The design of the track structure and direct fixation tracks will be based on
the following criteria: Only one rail break will be considered at any one time
on a given track structure.
D. The maximum allowable longitudinal gap in a rail due to a rail break will be 2
in. at the minimum expected rail temperature. Computation of this gap will
include both rail slip in the fasteners and deflection of the track structure.
4.6.4.10.18 Derailment Loads (DR)
The derailment load will be per Figure 4.6.4 applied without impact. The passenger
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rail car loading will be located up to 2 ft. 6 in. laterally from the center line of track.
The deck, superstructure and substructure will be investigated for this derailment
condition using the load combinations below.
A. For derailments where the wheels bear directly on the deck, the wheel load
distribution on the deck will be established with the effective distribution width
(E) of the derailment load as:
i. Deck between supports
Where S=Span length between centerlines of � = 0.58 ∗ � ≤ 3.0 ���� support
ii. Cantilever deck
iii. Moment
Where X=Distance from load to point of support� = 2.5 ���� + 0.2 ∗ �iv. Diagonal Tension
t=Thickness of deck� = 4 ∗ �B. When checking any component of the structure that supports two or more
tracks, only one train on one track will be considered to have derailed, with
other track(s) being loaded with stationary train(s) without impact.
C. Concrete Curbs on Closed-Deck Elevated Track Structure
A lateral load of 4,000 plf (perpendicular to the centerline of the track) over a
length of 5 ft., due to a glancing blow from a derailed transit car, will be
applied to top of concrete curbs on elevated track structures.
4.6.4.10.19 Design Load Combinations
See Sub Part 4.6.4.3 Design Methodology for more information. The Load
combinations presented below represent the minimum requirements and are in
addition to any other combinations the Lead Bridge Structural Designer deems
necessary to complete the design.
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A. Service Load Design
Table 4.6-6: SERVICE LOAD COMBINATIONS
Load
Case DL E
LL
IM
CF
FL
FR
N B SF W WL LF
OF-
CR,
SH,
TU,
TG
OF-
SE EQ IC CT RTM**
Allowable
Percentage
of Basic
Unit Stress
SLD I 1 1 1 1 1 100%
SLD II 1 1 1 1 1 125%
SLD III 1 1 1 1 1 0.5 1 1 125%
SLD IV 1 1 1 1 1 1 1 125%
SLD V 1 1 1 1 1 1 1 140%
SLD VI 1 1 1 1 1 0.5 1 1 1 1 140%
SLD VII 1 1 1 1 1 1 140%
SLD
VIII 1 1 1 1 1 1 150%
SLD IX 1 1 0.5* 1 1 1 150%
SLD X 1 1 0.5* 1 1 1 150%
* Live Load (LL) only-on one track
** RTM-includes only one of the following loads at one time (DR, FL and FR malfunction or RB)
Abbreviations
B Buoyancy LF Longitudinal ForceCF Centrifugal Force LL Live LoadCR Creep OF Other ForcesCT Collision: roadway vehicle with RB Rail BreakDL Dead Load RTM Rail Transit MaximumDR Derailment load SE SettlementE Earth loads SF Stream FlowEQ Earthquake loads SH ShrinkageFL Fastener longitudinal restraint force TG Temperature GradientFR Fastener radial restraint force TU Temperature UniformIC Ice or Snow loads W Wind on structureIM Impact WL Wind on Live Load
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B. Load Factor Design
Table 4.6-7: LOAD FACTOR COMBINATIONS
Load
Case DL E
LL
IM
CF
FL
FR
N B SF W WL LF
OF-
CR,
SH,
TU,
TG
OF-
SE EQ IC CT RTM**
LFD I 1.4 1.4 2.33 1.4 1.4
LFD IA 1.8 1.8 1.8 1.8 1.8
LFD II 1.4 1.4 1.4 1.4 1.4
LFD III 1.4 1.4 1.4 1.4 1.4 0.7 1.4 1.4
LFD IV 1.4 1.4 1.4 1.4 1.4 1.4 1.4
LFD V 1.4 1.4 1.4 1.4 1.4 1.4 1.4
LFD VI 1.4 1.4 1.4 1.4 1.4 0.7 1.4 1.4 1.4 1.4
LFD VII 1.0 1.0 1.0 1.0
LFD VIII 1.4 1.4 1.4 1.4 1.4 1.4
LFD IX 1.2 1.2 1.2 1.2 1.2 1.2
LFD X 1.2 1.2 0.7* 1.2 1.2 1.2
LFD XI 1.2 1.2 0.7* 1.2 1.2 1.2
* Live Load (LL) only-on one track
** RTM-includes only one of the following loads at one time (DR, FL & FR malfunction or RB)
C. Load and Resistance Factor Design: Red-Purple Bypass
A portion of the Red-Purple Bypass structure, defined above, will be designed
in accordance with the Load and Resistance Factor Design (LRFD) method
with the following modifications.
The load modifier, a factor for ductility, redundancy and track structure
operational importance, defined in AASHTO LRFD Equation 1.3.2.1-1 will be
based on:
i. Ductility Factor ηD=1.0 for structures. Non-ductile elements and
connections will not be used.
ii. Redundancy Factor ηR=1.0, except for non-redundant members and
connection ηR=1.05
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iii. Importance Factor ηI=1.05 for all track structures
The load combinations specified in the AASHTO LRFD Table 3.4.1-1 will be
modified as shown in the following table.
Table 4.6-8: LOAD AND RESISTANCE FACTOR COMBINATIONS
Load
Case
DL
E
CR
SH
LL IM
CF
FL
FR N B SF W WL LF OF-TU
OF-
TG
OF-
SE EQ IC CT RTM**
STR I 1.4 2.33 1.4 1.4 0.7/1.4 1.4
STR II 1.8 1.8 1.8 1.8 0.7/1.4 1.4
STR III 1.4 1.4 1.4 1.4 0.7/1.4 1.4
STR IV 1.4 1.4 1.4 1.4 0.7 1.4 1.4
STR V 1.4 1.4 1.4 1.4 0.7/1.4 1.4
EXTR I 1.0 0.5 1.0 1.0
EXTR II 1.4 1.4 1.4 1.4 1.4
EXTR
III 1.2 1.2 1.2 1.2 1.2
EXTR
IV 1.2 0.7* 1.2 1.2 1.2
EXTR V 1.2 0.7* 1.2 1.2 1.2
SERV I 1.0 1.0 1.0 1.0 0.3 1.0 1.0 1.0/1.2 0.5 1.0
SERV II 1.0 1.4 1.0 1.0 1.0 1.0/1.2
SERV
III 1.0 1.0 1.0 1.0 1.0 1.0/1.2
0.5
1.0
SERV
IV 1.0 1.0 1.0 0.7 1.0 1.0/1.2 1.0
* Live Load (LL) only
** RTM-includes only one of the following loads at one time (DR, FL & FR malfunction or RB)
4.6.4.11 Evaluation of Existing Elevated Track Structures
The reuse of portions of the existing elevated track structures requires Contractor to
perform an inspection, evaluation and rating along with a keep or replace determination
for existing elements that may be incorporated into the completed Project.
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4.6.4.11.1 Rating and Loading Constraints
The load rating of the steel members and connections will be performed according to
the requirements contained in Part 4.6 and the AREMA manual; and the actual
member properties, used in the rating, will be based on the section loss measured
during the field inspection. The following modifications will be used for the rating.
A. Impact load will be 65 percent of the full impact load, as calculated per
AREMA Manual, and applied to the structure. Reduction for speed is allowed
only for elements related to this Part.
B. Centrifugal force will act at 5 ft. above the top of the running rail.
C. Longitudinal Forces
i. General
Forces are applied at 5 ft. above top of running rails.
The longitudinal forces given for use in this Sub Part are based on a
ten-car train.
ii. Structures Supporting 1 to 3 Tracks
The longitudinal forces, applied simultaneously, will be 200 kips for one
track on the structure and 100 kips on 1 additional track.
iii. Structures Supporting 4 Tracks
The longitudinal force, applied simultaneously, will be 200 kips for each of
two tracks on the structure and 100 kips for each additional track on the
track structure.
D. Snow Load - The snow load will be taken as 25 psf. and combined with drift.
E. Footwalk Loading - 200 psf. for all footwalk, this pressure includes a materials
storage allowance.
4.6.4.12 Retaining Walls Loading
The loads, load combinations, and all other parts of the design associated with the
existing walls and Permanent retaining walls will be in accordance with Part 4.6 and Part
4.3 Geotechnical.
4.6.4.13 Miscellaneous Structures Loading
The loads, load combinations, and all other parts of the design associated with the
Miscellaneous Structures will follow the requirements of Sub Part 4.6.2.2 and the
following modifications.
4.6.4.13.1 Inertia Loads
Inertia loads due to the acceleration or braking of trains will be included in the loads
applied to the appurtenant structures, which are attached or connected to the track
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structure. The inertial loading will follow the requirements of Sub Part 4.7.4.3.12.
4.6.4.13.2 Ice Loads
Miscellaneous Structures, designed according to the Sub Part 4.6.2.2, will include ice
loads according to ASCE 7.
4.6.4.14 Temporary Structures Loading
The loadings, load combinations and all other parts of the design for Temporary
structures will be in accordance with Part 4.6, Part 4.3 Geotechnical and the
requirements herein. An increase in allowable stresses for Temporary structures, or for
Permanent structures withstanding Temporary loads, will not be allowed.
The requirements in AREMA Chapter 8, Part 20 – Flexible Sheet Pile Bulkheads and
Part 28 –Temporary Structures for Construction will apply with the following exceptions:
Article 20.3.4: The first 1 ft. - of depth of soil below the proposed mud line will be
neglected in calculating passive earth pressure. This will apply to all stages of
excavation at any given earth retention system.
Article 28.6.6 (b): Delete paragraph in its entirety [not used].
4.6.5 Design Criteria
4.6.5.1 Elevated Track Structures
4.6.5.1.1 General
A. Elevated track structure design and detailing will strive to achieve consistency
of structural member type and depth throughout the Project, although the
RPB and LBMM segments can be considered as separate structures.
Column and beam types will be developed to relate to one another in both
form and appearance. Beams will have a consistent depth across the bridge
span to the greatest extent possible. Where this is not feasible, use transition
sections to allow the beam depth to visually flow across the bridge from
deeper to shallower sections. Elevated track structure design elements will
also complement the existing adjacent elevated track structures.
B. Contractor is permitted to use “on-site” or “off-site” fabricated structures which
will moved into place provided they meet these technical requirements and
the following constraints relative to their design, fabrication and construction:
i. Allowances and considerations will be made for temperature variations.
ii. Allowances and considerations will be taken into account for the higher
variability in erection tolerances when connecting different prefabricated
materials in the field. When adjoining different materials the greater of the
material specified tolerances will be used for both materials.
C. Contractor will not use masonry, timber, aluminum, or lightweight concrete as
materials for Permanent elevated track structures with the exception that
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timber is acceptable only for walkways of open deck structures as noted
herein.
4.6.5.1.2 Superstructure
A. The following superstructure types will be the only types permitted for this
Project:
i. Rolled steel beams;
ii. Built-up steel plate girders; or,
iii. (subject to Sections 4.3 and 8.4.d of Part 1) as modified by Part 1, Exhibit
1, ATC 01.3 – Precast Segmental Box Girder Clarifications and ATC 17.0
– Precast Prestressed Concrete Beam Superstructure at North Mainline.
B. For the purposes of this Sub Part the terms "beams" and “girders”, when
referring to the superstructure, will be equivalent.
C. Contractor will not use through girders, steel box girders, trusses, tied arches,
prestressed concrete beams, prestressed precast slabs or deck bulb-tee
girders (including thin flange deck bulb-tee girders), prestressed or post-
tensioned concrete U-beams, tri-beam sections or double tee girders, post-
tensioned members or non-prestressed precast slabs for Permanent
structures except (subject to Sections 4.3 and 8.4.d of Part 1) as modified by
Part 1, Exhibit 1, ATC 01.3 – Precast Segmental Box Girder Clarifications
and ATC 17.0 – Precast Prestressed Concrete Beam Superstructure at North
Mainline.
D. There will be a minimum of three stringers per track for closed deck track
structure except (subject to Sections 4.3 and 8.4.d of Part 1) as modified by
Part 1, Exhibit 1, ATC 01.3 – Precast Segmental Box Girder Clarifications
and ATC 17.0 – Precast Prestressed Concrete Beam Superstructure at North
Mainline; and there will be a minimum of two stringers per track for open deck
track structure. The exterior stringers will be designed for a capacity equal to
or greater than the interior stringers. Elevated track structures with
intermediate hinges (pin and link hanger connections) will not be allowed.
When two stringers are used for new open deck track structure, the minimum
spacing will be 5 ft. 0 in. and this will govern over AREMA requirements of 6
ft. 6 in. described in Chapter 15, Section 1.2.4, Subsection b.
E. Fatigue categories A, B, B’, C and C’ will be acceptable for the structural steel
elements and their details; fatigue categories D, E, E’ and F will not be
acceptable.
F. Bonding of the steel superstructure across discontinuities will be required,
see Parts 4.9 and 4.10.
G. Within the minimum limits shown in Part 3, steel stringer superstructures will
have a closed, reinforced concrete deck designed to be composite with the
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beams. All secondary superstructure concrete pours, including but not limited
to plinths, curbs, barriers and overlays, will not be used in the structural
design capacity of the superstructure. Contractor will design all closed decks
using cast-in-place concrete. Stay-in-place forms and stay-in-place concrete
deck panels for deck slab will not be allowed. On closed deck structures, drip
plates will be provided on the bottom flanges on the exterior side of exterior
steel beams to keep water runoff away from bearings and bridge seats.
H. The stringers will be designed to carry the weight of the fluid concrete deck
as well as their own weight without shoring. Camber will be in accordance
with AREMA.
I. Sections in positive flexure that are composite in the final condition but non-
composite during construction will be investigated during the various stages
of the deck placement. The effect of overhang concrete and brackets, screed,
walkways, formwork, and wind loads on the pouring sequence will be
evaluated and accommodated by the design.
J. Contractor will provide one unobstructed longitudinal run per track for current
and future use-including web openings through diaphragms and cross
girders. The size and location of the openings will be provided by Contractor
and submitted to CTA as a part of the Intermediate and Final Design
Submittals.
K. Stringers will be spaced to allow for future deck replacement during staged
construction and the incorporation of all transit systems, including but not
limited to traction power, signals, communication. During future deck
replacement, each track will be required to be independently stable while
allowing normal train operations on the adjacent track(s).
L. Red-Purple Bypass (NM5)
The criteria for deflection listed in AASHTO LRFD Bridge Design
Specifications, Section 2.5.2.6 will be considered optional at the discretion of
the Lead Bridge Structural Designer for this structure.
4.6.5.1.3 Substructure
A. The following substructure types will be the only types permitted for this
Project:
i. Steel cross girders at the locations shown on sheets ST-1201 thru ST-
1213, ST-6501 thru ST-6504 in the Base Case Plans.
ii. Steel columns at the locations as shown on sheets ST-1201 thru ST-1213
in the Base Case Plans.
iii. Steel Box Cross Girder at the straddle bent depicted as Bent 13P on
sheet ST-1109 of the Base Case Plans.
iv. Cast-in-place concrete bents, piers and abutments.
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v. Pre-cast concrete elements are allowed.
B. Prestressed or post-tensioned concrete elements of any kind will not be
allowed for use.
C. Steel cross girders will not support more than one wheel line of rail vehicle
load in a cantilevered position. This criteria requires that the distance from the
centerline of exterior column of the bent to the centerline of supported track,
in the cantilevered portion of the cross girder, is equal to or less than 2 ft. 4 ¼
in. An exception to this requirement will be made along the east side of the
LBMM portion of the Project where the distance from the centerline of exterior
column of the bent to the centerline of proposed track, in the cantilevered
portion of the cross girder, will be allowed up to 3 ft. 4 ¼ in.
D. Steel cross girders that are shored or partially shored during construction will
be investigated for dead load deflections during all stages of construction.
Additional cross girder cambering and/or adjustments to slab dead load
deflection diagrams may be necessary to maintain proposed top of rail
elevations.
E. Fatigue categories A, B, B’, C and C’ will be acceptable for the structural steel
elements and their details; fatigue categories D, E, E’ and F will not be
acceptable. Steel columns will not be welded to the bottoms of steel cross
girders.
F. The column base for steel columns, when used for elevated track structures,
will consists of a concrete pedestal that terminates a minimum of 2 ft.6 in.
above finished grade and no higher than 3 ft. 6 in. above grade with the base
fully exposed and free to drain. The concrete pedestal dimensions will be a
minimum of 3 in. beyond the plan size of the base plate on each side. Anchor
rods will extend 6 in. above the top of nuts on the steel bearing plate to allow
for future adjustment. The use of leveling nuts at supports for elevated track
structures will not be allowed. Bases will include electrical isolation (pad,
bushings, and washers) in accordance with other articles of this document.
G. All beam seats at abutments and pier caps will be detailed with a slope to
drain moisture accumulation. Reinforcement will be provided for concrete
pedestals on piers caps and abutments for pedestal heights greater than 3 in.
H. Substructure bents will be numbered and labeled consistent with the current
CTA numbering system. The field numbering at each bent will be 3 in. high by
2 in. wide numbers with black colored paint. The use of stencils will be
required; and the materials and process will be included in Construction
Process Plans per Part 2.5. Placement of the bent number will be on a bent
column at a of height 6 ft. above finished grade on a side viewable from the
direction of an adjacent, parallel roadway, alley, or pathway where vehicles
may be continuously driven on.
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4.6.5.1.4 Foundations
A. General: An appropriate foundation type will be selected based on site
conditions, site borings, geotechnical work, an analysis of the loads to be
supported and serviceability criteria. See Part 4.3 Geotechnical for additional
information.
B. Foundation Types: The following foundation types will be the only types
permitted for this Project:
i. Drilled shafts.
ii. Micropiles – where drilled shafts are not technically feasible and where
stray current from electrified tracks will not induce or is prevented from
inducing corrosion to the casing.
iii. Spread footing (only at locations shown on sheets ST-1114, ST-1116 and
ST-1117 of the Base Case Plans or in this Sub Part).
At Bents 6050 thru 6053 and the Clark Relay House, spread footing
foundations will be permitted. At Bents 6050 thru 6053, the bottom of any
new spread footing will match the bottom of the existing spread footing at the
respective bent. Driven piles will not be permitted.
C. Drilled Shafts: Drilled shafts supporting elevated track structures will be
designed and detailed as end bearing on bedrock or hard pan (very stiff to
hard stratum). Bells or enlarged bases for shafts will be permitted in cohesive
type soils where the angle of inclination of the bell from vertical will be no
greater than 30°. In addition, the enlarged base of the shaft is only allowed to
be considered 100 percent effective if the bell is dry, cleaned and inspected.
D. Micropiles: Micropiles supporting track structures will be rock socketed and
fully cased from the footing thru the plunge length into rock. The soil
surrounding the concrete cap will not be used to resist lateral loads. Battered
piles are allowed but no portion of a micropile may extend outside the CTA’s
right-of-way.
4.6.5.1.5 Structure Specific Design Criteria
A. Elevated Track Structure at RPB:
i. The existing structure at the south end of the RPB is the Belmont station
closed deck structure with concrete plinths and jointed rail. Widening of
the structure is required to install the Bypass track; and the structure
widening will be designed and constructed as an “in-kind” widening
through the use of a design approach, structure depth, elements and
materials that match the existing. The limits of closed deck along the
Bypass Track will be as shown in Part 3; and a concrete barrier will be
designed for the outside edges of the closed deck portion of the Red-
Purple Bypass structure.
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ii. For a steel box girder design at Bent 13P, the design and construction of
the box girder will provide two distinct sets of tension components (for the
tension elements) such that either set will provide the full load carrying
capacity in the event that a component of one set were to fail and lose its
load carrying capacity. The connections of the tension elements will be
bolted connections.
iii. From Bent 7P thru Bent 19P, as shown in the base case plans in Part 7,
the stringers will not be chorded but will be horizontally curved to
approximately follow the alignment. Additionally, the closed deck edge
and noise barrier will not be chorded beyond the extent to which the
chord deviates from the true curve (offset to the required clearance) by
more than ¼ in., with chord length not to exceed 8 ft.
B. Elevated Track Structure at RPB-NM:
i. The south end of the RPB-NM section is contiguous with the Belmont
station closed deck structure. Based on the required track alignment
changes as part of the project in this area, portions of the existing plinths
and deck will be removed, modified and/or reconstructed to
accommodate the Temporary and Permanent track alignments as
described in Part 3 of the RFP. Additionally, Contractor will also design
and construct additional barriers surrounding the existing deck openings
at the Belmont deck as shown on sheet ST-1101 of the Base Case Plans
and meeting the technical requirements. To avoid imparting load into the
existing adjacent structures due to thermal forces, CWR terminations in
the area of the interface of the new structure and the existing structure
will be allowed in the approximate locations shown in the Base Case
Plans, included in Part 7, at the discretion of the Lead Bridge Structural
Designer (LBSD).
ii. The north end of the RPB-NM section requires widening and modification
of the existing open deck structure to accommodate the new track
alignments. Contractor will design and construct additional foundations,
substructure and superstructure in accordance with these technical
requirements. To avoid imparting load into the existing adjacent
structures due to thermal forces, CWR terminations in the area of the
interface of the new structure and the existing structure will be allowed in
the approximate locations shown in the Base Case Plans, included in Part
7, at the discretion of the LBSD.
C. Elevated Track Structure at LBMM
i. Where retaining walls adjoin elevated track structure abutments or curtain
walls, an expansion joint will be placed full height to the bottom of the
barrier. The expansion joint will be in accordance with Sub Part 4.6.6.2.2.
Curtain walls at elevated track structure abutment wall corners will be
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cast-in-place walls integral with the abutment walls and extending to the
back of the footings.
ii. The south end of the LBMM-NM improvement will be tied into and
integrated with the existing open deck structure that extends north from
the Wilson station and currently terminates at the Leland Avenue
Abutment south of Bent 7134 as depicted on the Base Case Plans.
Contractor will inspect and verify all as-built conditions of the existing
open deck structure and Bent 7133 and determine any required
modifications or Temporary support that may be required to validate
existing open deck structure removals and proposed structure loads
imposed on the existing structure.
iii. The limits of closed deck along the LBMM-NM will be as shown in the
Base Case Plans. Contractor will also design and construct continuous
noise barriers along the east and west sides of the new structure.
iv. The existing embankment soils and retaining walls (including bridge
abutments) along the LBMM-NM embankment will not be relied upon for
vertical or lateral support of new Permanent structure. Related to the
existing embankment soils, the prohibition stated above applies to
embankment soils above the existing adjacent alley or street elevation
nearest the existing embankment structure.
4.6.5.1.6 Design to Accommodate Inspection and Maintenance
A. Structural materials and details will be selected to allow any needed
maintenance and repairs to be performed without significant interruptions to
transit service.
B. All elevated structures, including but not limited to joints and bearings, will be
accessible for inspection and maintenance, and will be designed, detailed
and constructed by Contractor to allow for replacement of joints and bearings.
C. A minimum of 7 ft. of overhead clearance will be provided from the finish
ground elevation beneath the structure to the lowest longitudinal elements of
the elevated track structure in order to facilitate future ground level
inspection. A minimum of 3 ft. of overhead clearance will be provided from
the finish ground elevation beneath the structure to the lowest transverse
structural elements in order to facilitate future ground level inspection.
D. Design elements will not inhibit the access of structural components or any
non-structural element that will need future inspection and maintenance.
Open-framed superstructures will be accessible by a ladder or a man lift.
E. The steel box girder at Bent 13P, will be accessible for interior inspection
during and after construction. Access doors will meet OSHA minimum
requirements. They will be located on each end, be lockable, will swing into
the box girders and placed at locations that do not impact traffic below. The
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minimum depth inside the box will be 4 ft. and interior diaphragms will have
sized with OSHA minimum openings. Contractor will include the necessary
measures to address moisture control inside the box girder. Any venting or
drainage openings to the interior of the box girder will be placed in hidden
locations. Box girder penetrations greater than 1 in. diameter through the
exterior will be covered with wire mesh to prevent vermin and birds from
accessing the interior.
F. Lighting fixtures, light switches, and duplex receptacles will be located inside
the steel box girder. Light fixtures and receptacles will be at an equal spacing
of 20 ft. maximum. Duplex receptacles will be served by 120 volts and
protected with 20-amp breakers. The receptacles will be grounded (GFCI 20-
amp, 125-volt). Each duplex receptacle circuit will have a minimum 1800-watt
capacity, and will serve no more than 25 duplex receptacles. Each lighting
fixture will have a minimum capacity of 100 watts. Lighting at each fixture will
provide a minimum of 2200 initial lumens output; lighting fixtures and bulbs,
adjacent to the access doors of the box girder, will be installed to prevent
blinding light as maintenance personnel access the interior of the box girder.
Conduits that supply power to the electrical components in the steel box will
be concealed and will not be surface mounted, except within the interior of
the box girder.
4.6.5.1.7 Structure Elements
A. Closed Deck: Contractor will design and construct all closed elevated track
structure decks using cast-in-place reinforced concrete, which will have a
minimum thickness of 10 in. or (subject to Sections 4.3 and 8.4.d of Part 1) as
modified by Part 1, Exhibit 1, ATC 01.3 – Precast Segmental Box Girder
Clarifications. For elevated track structure decks, stay-in-place concrete deck
panels and stay-in-place deck forms will not be permitted. Elevated track
structure closed decks will be continuous:
i. in the longitudinal direction between transverse expansion deck joints
ii. In the transverse direction from outside barrier to outside barrier, except
as shown in Part 3
In areas of special trackwork, the closed deck will be continuous in the
transverse direction across the full width of the four track section as shown on
Sheet ST-1102 in Base Case Plans. An integral curb, monolithically placed
with the deck, will be required beneath the noise barriers at the exterior
edges of the deck. No deck joints will occur within 50 ft. of any special track
work. The minimum distance between transverse deck expansions joints will
be 120 ft. or as laid out in the Base Case Plans or (subject to Sections 4.3
and 8.4.d of Part 1) as modified by Part 1, Exhibit 1, ATC 01.3 – Precast
Segmental Box Girder Clarifications.
Drip notches will be provided on the underside of the deck inboard of the
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deck fascia. Reinforcing steel layout in the closed deck will accommodate all
required openings for interface disciplines including but not limited to
electrical, drainage, traction power, signal, and communications.
B. Deck Drainage: The technical requirements for deck drainage and outlets can
be found in Part 4.5 Drainage Systems.
C. Expansion Joints:
i. All elevated track structure expansion joints will be pre-formed
elastomeric strip seals. The maximum spacing between strip seal
expansion joints will be controlled by the limitations of the strip seal. In
curved structures or in portions of the Red-Purple Bypass structure where
the total movement exceeds the limits of the strip seal, a modular
expansion joint will be used. Strip seals can accommodate small amounts
of curvature, but Contractor will need to demonstrate that the strip seal
can accommodate differential expansions due to curvature and/or skew
before using them in these situations. Finger type expansion joints on
Permanent elevated track structures will not be allowed. Longitudinal
expansion joints on proposed elevated track structures or widened
structures will not be permitted.
ii. Strip seals will be installed in one continuous piece for the entire width of
the proposed and existing elevated track structure decks. The steel
locking edge support rails for strip seals will be either one-piece extrusion
(rolled section) or a combination of extruded and stock plate, shop
welded. The locking portion of the steel edge support rail will be extruded,
with a cavity, properly shaped to allow insertion of the strip seal gland and
the development of a mechanical interlock. The expansion joint will
terminate 5 in. in from the inside face of the barrier or curb with an upturn
angle of 60 degrees. The expansion joints will follow the skew, however
for skews greater than 30 degrees the expansion joint will turn to upturn
into the barrier 90 degrees. Steel rails, studs and metal components for
the expansion joints will be galvanized.
iii. The top of joint locking edge rail will be installed and recessed ¼ in.
beneath the top of slab with a tooled edge. All joint installation details will
allow for future access and replacement of the strip seal. Strip seal
expansion joint elastomeric seal will be installed per the manufacturer’s
recommendations. Joint elevation termination to be subject to deck
drainage requirements.
D. Plinths:
i. General criteria for the plinths and plinth mock-up are located in Part 4.8.
The reinforced concrete plinth will be rigidly connected to the deck. If
stirrups that protrude from the concrete deck are used, they will extend to
provide a minimum of 2 in. clear from the deck slab to allow both the
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longitudinal reinforcing steel and the plinth concrete to lock under the
stirrups. The final stirrup height will be designed to suit the final concrete
plinth height and reinforcement design. To combat potential stray current
leakage or flow within the concrete plinth, any damage to the epoxy
coated reinforcement in the concrete plinth or any reinforcement
protruding from the deck, will be repaired according to Concrete
Reinforcement Epoxy Coated specification: number 03 20 10.
ii. Steel reinforcement within the plinth will be detailed for severe exposure
conditions. Severe exposure conditions are defined as: exposure to
deicing salts or other corrosive chemicals and/or exposure to freeze-thaw
cycles.
E. Noise Barriers:
i. Noise barriers will have a minimum height of 42 in. above high rail of
adjacent track or adjacent walkway surface, whichever is greater.
Minimum thickness will be 6 in. Permanent barriers will be reinforced
cast-in-place concrete or (subject to Sections 4.3 and 8.4.d of Part 1) as
modified by Part 1, Exhibit 1, ATC 19.0 – Precast Concrete Noise Wall
Barriers. Subject to Part 1 Section 4.3, in accordance with the Proposal
Extract in Part 1, Exhibit 1 on page 3.1-35, Contractor will utilize context-
sensitive form liners. Precast concrete barriers or slip forming of cast-in-
place barriers will not be allowed for Permanent applications on elevated
track structures or retaining walls except (subject to Sections 4.3 and
8.4.d of Part 1) as modified by Part 1, Exhibit 1, ATC 19.0 – Precast
Concrete Noise Wall Barriers.
ii. The noise barrier will be continuous in all areas along the closed deck
structure including when wayside platforms or other system elements
may interrupt the line of the barrier and require the barrier to transverse
around such wayside platforms and elements. In the event an intermittent
encroachment of the walkway is proposed for a trackside appurtenance,
as detailed in Appendix 3D and Sub Part 4.8.5.3.37, and sufficient width
is not available for the noise barrier thickness noted above, the noise
barrier thickness may be reduced at the discretion of the Lead Bridge
Structural Designer for a distance of up to 3 ft. maximum. The reduced
thickness noise barrier, if utilized, will be subject to the same design
requirements as the full thickness noise barrier described above. All joints
in the noise barrier will be closed or filled.
F. Open Deck:
i. The open deck structure walkways will be 4 in. x 6 in. wood stringers and
wood decking in accordance with the applicable provisions in Sub Part
4.8.5.2. Where track ties are supported directly on the top flanges of
rolled beams or built-up girders, cover plates will not be allowed. Bolts or
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projections, above the top flange of track stringers or the top surface of
structural elements that directly support track ties, will not be allowed.
ii. Access areas, platforms and walkways for the relay houses will be
fiberglass reinforced plastic as described in specification number 06 51
50.
G. Structural Steel Members
i. Minimum Sizes for Members and Welds: Primary fabricated structural
steel members for elevated track structures, such as stringer flanges and
webs, cross frames for curved girders, floor beams, splice plates,
stiffeners, connection plates, etc., will have a minimum thickness of ½ in.
ii. Secondary fabricated structural steel members, such as wind bracing and
diaphragms, in the superstructure will have a minimum thickness of ⅜ in.
iii. The minimum thickness criteria apply to rolled sections as well as built-up
members.
Minimum size criteria are as follows:
Girder flange width: 12 in. nominal (>11.50 in.);
Girder flange thickness: 1 in. nominal (>0.950 in.);
Filler plates at splices: 1/32 in.;
Fillet weld size: 5/16 in. (except for seal welds).
iv. Diaphragms, Cross Frames and Lateral Bracing:
The design and spacing of diaphragms, cross frames, lateral bracing
and their connections for elevated track structures will be in
accordance with AREMA Chapter 15. For the Red-Purple Bypass
structure, design and construction for the cross frames, lateral bracing
and diaphragms will follow the more stringent requirements of the
AREMA manual or the AASHTO LRFD specifications listed in Sub
Part 4.6.2.1. The maximum spacing for these members in the Red-
Purple Bypass structure will be at 1/8 points within each span.
Steel diaphragms and cross frames at expansion piers or abutments
will be designed to allow for jacking on the diaphragm or cross frame
for resetting, repair or replacement of the bearings. If jacking cannot
be performed on the end diaphragms, then provisions will be made in
the design of the beam seats to allow jacking from directly under the
beam. For this scenario, the beams will be provided with jacking
stiffeners. Jacking stiffeners will also be provided for beams in cross
girder pockets. Stiffeners will be designed for 150 percent of the
bearing reaction due to dead load.
Cross frames or diaphragms at closed deck stage construction lines
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may require additional detailing efforts to ensure quality placement.
For structures not designed for significant curvature with maximum
differential displacements of up to 1 in. at deck stage construction
lines, standard long slot holes will be detailed at one end of the
bracing. For structures with maximum differential displacements
greater than 1 in., the designer will investigate combinations of long
slots in both the bracing and main member connection plates to
accommodate the differential displacements. Include a note that bolts
in slots will be finger tight until the second stage pour is complete, and
position slots so bolts start at one end with no concrete load and finish
near the opposite end under deck load, allowing maximum
displacement without laterally stressing main members. All holes will
have appropriate hardened or plate washers. Long slots will not be
detailed on webs of members. Structure plans will clearly detail the
initial erected position of slots and bolts.
v. Connection Requirements
All field connections will be bolted with high strength ASTM F3125
Grade A325 bolts.
Structures supporting rail or roadway vehicles - 7/8 in. diameter
minimum slip-critical high strength bolts.
Other structures - 3/4 in. diameter minimum. For corrosive
environments, bolts are designed as bearing type but to be installed
and tensioned to slip critical levels. For non-corrosive environments,
bolts will be designed and installed as bearing type.
Galvanized Faying Surfaces: Galvanized faying surfaces will first be
hot dip galvanized in accordance with the requirements of ASTM
A123 and subsequently roughened according to the AREMA manual.
Power wire brushing is not permitted. When properly prepared, the
galvanized faying surface is designated as Class C for design.
Column splices will be designed as bolted slip-critical connections.
Bolt installation methods will be in accordance with AREMA Chapter
15, Section 3.2 and will be limited to the Turn-of-Nut method.
The use of ASTM F1852, F2280 and F3125 Grade A490 will not be
allowed for Permanent structures.
vi. Welding
All welding electrodes will be E70XX.
Field welding will not be allowed, except for stud shear connectors as
defined in Part 4.6.
The following welds will not be allowed: Intersecting welds, partial
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penetration groove welds, stitch welds and field splicing elevated track
structure elements.
H. Bearings
i. General: The following bearing types, modified as needed to meet the
requirements of the Project, will be the only types permitted for this
Project:
Type I, Type II and Type III elastomeric bearings as detailed by the
Illinois Department of Transportation’s Bridge Manual.
Low profile fixed bearings as detailed by the Illinois Department of
Transportation’s Bridge Manual.
High Load Multi-Rotational (HLMR) bearings that are of the disk type.
ii. All bearings will be required to accommodate skew and curvature effects,
initial camber, construction loads, misalignment, construction tolerances,
support settlement, thermal effects, fabrication tolerances, in addition to
design loads.
iii. Type I bearings will only be used at concrete abutments or piers with
concrete caps when the rubber portion of the bearing is in direct contact
with the concrete. Locations with geometric constraints or loading
conditions may require the use of HLMR bearings. HLMR bearings will be
required for structures designed for curvature.
iv. All members will be positively attached to their supporting bearings by a
connection which can resist the longitudinal and transverse forces which
may be imposed on the connection.
v. The bearings will be designed for the effects, due to all possible loading
conditions, which include but are not limited to compressive stress,
compressive deflection, shear deformation, rotational capacity, seismic,
stability, reinforcement strength and anchorage. Guides and restraints will
be used to prevent and/or limit movement in one or more directions.
vi. Potential uplift at the bearings will be investigated for all construction
stages. Uplift on bearings of any kind will not be allowed. If necessary,
end diaphragm counterweights will be designed and constructed to resist
uplift forces.
vii. Bearing Components:
Masonry plates will have a minimum thickness of 1 in. Top bearing
plates will have a minimum thickness of 1 ½ in. Masonry plates will be
positively secured to their supports by bolting. Masonry plates detailed
for installation within a steel cross girder bearing pocket may require a
special non-bolted detail between the masonry plate and bearing
bracket support plate. Threaded studs will be utilized for the
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connection between bearing sole plate and supported element.
If the inclination of the underside of the girder to the horizontal
exceeds 0.01 radian, a tapered top plate will be used in order to
provide a level load surface to be placed on the bearing. This
requirement will be met under full dead load at the mean annual
temperature for the structure site.
Anchor bolts will have a minimum diameter of 1 in. Anchor bolt holes
in pedestals, masonry plates, or sole plates will be larger in diameter
than the bolts in order to accommodate the minimum thickness of an
electrical isolation bushing. Anchor bolts/rods will extend a minimum
of 12 in. into masonry substructures. Anchor bolts/rods will be
swedged or threaded. Anchorage to concrete will be designed in
accordance with ACI 318.
At least 6 in. of cover will be provided between anchor bolts and the
closest edge of the concrete.
Bearings installed on concrete bearing surfaces will be electrically
isolated at their interface. If Contractor elects to use integral pier caps
or similar details that embed the beam, beams will be required to be
electrically isolated either through bearings or alternative methods.
For further discussion, see description of electrical isolation materials
in the materials portion of Part 4.6.
Adjusting shims will be provided with each bearing assembly.
viii. High Load Multi-Rotational Disc Bearings
Disc bearings will consist of a polyether urethane structural element
(disc) between an upper and lower external steel load plate. Disc
expansion bearings may also include a flat sliding surface to allow for
horizontal movement.
The confining elements of the lower external steel load plate may be
integrated into an appropriately designed masonry plate or may be
designed as separate elements with the lower load plate bolted or
welded to the masonry plate.
For fixed disc bearings without a flat sliding surface, the confining
elements of the upper external steel load plate may be integrated into
an appropriately designed sole plate or may be designed as separate
elements with the upper load plate bolted or welded to the sole plate.
For expansion disc bearings with a flat sliding surface, the confining
elements of the upper external steel load plate may be integrated into
an appropriately designed base plate that also supports the sliding
element.
Disc bearings will be equipped with a shear restriction mechanism to
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prevent movement of the disc.
Disc bearings will be designed and constructed to accommodate all
displacements, rotations, distortions and loads due to the demands
from the connecting structural members.
4.6.5.2 Existing Elevated Track Structure at RPB
4.6.5.2.1 Ravenswood Structure
A. At the Ravenswood structure between and including existing bents RV05 and
RV28, the following list of members will be replaced in-kind and are
considered included elements of the work.
i. All original riveted top and bottom flanges of the stringers (estimated to be
25 percent of the top flanges and 80 percent of the bottom flanges)
ii. Intermediate transverse stiffeners where flanges are replaced and others
where deemed necessary by the LBSD
iii. All lateral bracing attached to bottom flanges that are being replaced
iv. All original riveted bottom flanges of each bent’s cross girder (estimated
to be 85 percent of the bents)
v. All tower sway bracing
vi. All stringer expansion pockets including bearings, except at bents RV11
and RV 14
vii. All column pedestals and bases
viii. All foundations
B. Cover plates and bolts will be installed to cover or fill holes, which are
structurally acceptable, in existing members that are to remain.
C. This list is the base work that is required for the rehabilitation of the RV
portion of the RPB. The total weight for the structural steel repair portion of
this list is 255,000 lbs. For the connection of the Red-Purple Bypass track to
the RV structure, Contractor will determine the required new elements and
members to support the track work and other systems.
4.6.5.2.2 RPB-NM Structure
A. At the RPB-NM structure between and including existing bents 6047 and
6053, the following list of members will be replaced in-kind and are
considered included elements of the work.
i. Stringer flanges not meeting the normal rating requirements described in
these technical requirements
ii. Intermediate transverse stiffeners where they are deemed necessary to
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be replaced by the LBSD
iii. Stringer expansion pockets
B. Cover plates and bolts will be installed to cover or fill holes, which are
structurally acceptable, in existing members that are to remain.
C. This list is the base work that is required for the repair of the existing portion
of the RPB-NM, which will remain. The total weight for the structural steel
repair portion of this list is 40,000 lbs. For the modifications of the existing
structure required to accommodate the new tracks’ alignments, Contractor
will determine the required new elements and members to support the track
work and other systems.
4.6.5.2.3 Inspection and Rating
A. In order to determine if the base work (listed above) addresses all of the
necessary repairs, Contractor will inspect and document the condition of the
RV structure and a portion of the RPB-NM. Prior to starting design work,
Contractor will inspect and document the condition of all structural elements
for:
i. RV structure between and including bents RV05 to RV28.
ii. RPB-NM structure between and including bents 6047 to 6053
B. The limits of the inspection by Contractor will include all structural members,
including but not limited to all steel members, incidental members for signal,
utilities supports, existing equipment or other platforms. Existing Bridge
Condition Reports are provided, for reference only, in Part 7.
C. The National Bridge Inspection Standards will be followed and the results of
the inspection will be summarized in reports that will follow the format of an
Illinois Department of Transportation’s Bridge Condition Report (BCR).
D. The purpose of the inspection is to document the existing condition, gather
information to be used in load ratings of members, which in turn will be used
to determine which elements are in need of replacement. Since many of the
existing structural members are built-up sections, only full length replacement
of members or members’ elements will be allowed. Elements are defined as
the pieces or components that make up the various members. For example,
the stringers and cross girders are built-up sections of the following elements:
top flange angles, web plate and bottom flanges angles. The webs of the
stringers and bent cross girders will be the only existing structural elements
allowed to be repaired without full element or member replacement when the
number of repairs for one web is limited to three repair areas.
E. Contractor will document and provide two separate BCRs (one for each of the
two structures) as Design Submittals that provide all the inspection findings,
normal and maximum ratings and a summary list of all elements which will
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need replacement or allowable repair. Cut holes in the high stress regions of
the cross girder web plates will be included in the summary list and will be
repaired. The ratings of members will include, but not be limited to, the
stringers, cross girders and columns.
F. The following evaluation criteria will be used to determine which elements will
require replacement. Replacement is required for:
i. Existing steel members where the normal rating of the member is less
than the currently required load level.
ii. Existing steel members or elements with a crack, detected visually or with
magnetic particle testing.
iii. Existing fasteners (rivet or bolt) where either the end of the fastener has
50 percent or greater loss in the volume of the head/nut or where the
fastener is corroded to the point where 50 percent or greater of the
head/nut can be removed with a strike from a 2 lb. ball-peen hammer.
G. The summary list of members to be provided will indicate, at a minimum, the
location of elements, size of element, description of element, defect location,
type, and size on the elements and members, reason for replacement or
allowable repair, weight of replacement elements or elements for allowable
repairs and a total steel weight for all work.
H. All BCRs will include the stamp and signature of the Lead Bridge Structural
Designer and will be submitted to the CTA as Design Submittals prior to
ordering material for the rehabilitation as required.
4.6.5.2.4 Rehabilitation
A. All superstructure and bents for the RPB rehabilitation Work will be designed
and constructed utilizing structural steel. Contractor will utilize the summary
list of members from the BCRs to develop a complete design and perform the
required Work. Existing FCM structural steel members or elements that
require replacement or allowable repair will be modified with materials that
meet all FCM requirements.
B. The rehabilitation will be designed and constructed as a system and account
for the methods of construction where required. Existing and rehabilitated
expansion devices will be required to act uniform across support location.
C. Existing secondary members, including but not limited to angles, filler plates,
brackets, that require complete removal for replacement of primary or
deteriorated members will be replaced.
D. All replacement members or elements will be required to match the general
aesthetics of the existing member or element being replaced. High strength
bolts will be an acceptable replacement for existing rivets.
E. No open fastener holes will be allowed to remain, all open holes will be filled
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with a bolt, nut, and washers. Field welding will not be allowed. Where shim
plates are to be used, a maximum of three will be allowed and will require
proper design and detailing. A complete rivet removal procedure will be
required prior to Work.
F. The column base plates and concrete foundations for Bents RV05 thru RV28
will be designed, removed and reconstructed to provide a reinforced concrete
pedestal top elevation that is a minimum of 2 ft. 6in. above final grade and
match the existing column base locations in plan. At locations where the
proposed Red-Purple Bypass track and relay house columns are adjacent,
foundations and pedestals will be designed and constructed to accommodate
additional columns as required.
G. The RV structure south of Bent RV05 will be removed, redesigned, modified
and reconstructed as needed to complete the Work; new foundations and
bents at Bents RV03P and RV04P along with new superstructure south of
Bent RV05 will be designed and constructed. All existing bracing and steel
framing members, in conflict due to reconstructed pedestal height
requirements, will require design and construction to eliminate any conflicts;
and the affected members will be replaced with new material.
H. The existing RV structure rehabilitation Work will require stage construction.
All design and detailing will be required to account for additional stage
construction loading and will be incorporated into the design calculations and
detailing.
I. Upon completion of the rehabilitation and modifications, the existing RV and
portions of the RPB-NM structures will be blast cleaned and painted. The
painting limits for the existing structures will be:
i. Between and including Bents RV05 thru RV28,
ii. Between and including Bents 6047 thru 6061.
J. Painting includes the structural steel superstructure and steel substructure.
All top flanges in contact with track ties and all locations inaccessible to be
painted with ties in place will be repainted prior to tie replacement. Contractor
is alerted that the existing structural steel coating may contain lead based
paint and will follow the requirements of Part 3.7.
4.6.5.3 Existing Elevated Track Structure at Montrose Avenue
A. Improvements for North Main Line at Montrose Avenue include replacement of
existing foundations and painting of existing structural steel.
B. Bents 93 and 94 are located adjacent to the south and north curb lines of
Montrose Avenue. Each bent line is comprised of four individual foundations
supporting a single column and pair of open deck track stringers. Foundations at
Bents 93 and 94 will be designed, removed and reconstructed. Design and
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construct foundations and foundation pedestals in accordance with requirements
outlined for foundations and substructure in Part 4.6. The existing column bases
are anchored to pedestals that extend approximately 6 in. above adjacent grade.
Height requirements for new pedestals require the removal of the lower portion of
the existing column with the addition of new column base assemblies.
Reconstruction at Bents 93 and 94 will be completed in advance of constructing
the Montrose interlocking track work.
C. Upon completion of the Bent 93 and 94 foundation replacements, the existing
NML structure between and including Bents 91 thru 96, will be blast cleaned and
painted. Painting includes the structural steel superstructure and steel
substructure. Contractor is alerted that the existing structural steel coating may
contain lead based paint and will follow the requirements of Part 3.7.
4.6.5.4 Retaining Walls
4.6.5.4.1 General
A. Permanent retaining walls will be designed in accordance with the AREMA
manual and applicable standards and references outlined. Retaining walls will
be designed to withstand all loads including, but not limited to: dead weight of
the wall, earth and hydrostatic pressures and any live load surcharge.
B. For retaining structures constructed adjacent to the railroad tracks, Contractor
will determine if the structure is within the soil pressure zone of influence due
to the rail vehicle loading. If applicable, the surcharge load will be included.
Any adjacent surface elements that may exert a surcharge loading on the
retaining structure will also be considered.
C. New retaining walls will be similar in appearance to existing adjacent
retaining walls with the exception that Subject to Part 1 Section 4.3, in
accordance with the Proposal Extract in Part 1, Exhibit 1 on page 3.1-36,
Contractor will utilize context-sensitive form liners as appropriate.
Consistency of wall concrete façade with the adjacent retained embankment
walls is required.
D. The following types of retaining walls will be the only types permitted for
Permanent wall structures of this Project:
i. Cast-in-Place Concrete Walls
ii. Cantilever sheet pile walls and cantilever soldier pile walls may be used
when top-down construction is warranted. Soldier pile walls will have a
reinforced concrete facing that is a minimum of 12 in. thick. Shotcrete will
not be used for final finish facings. Lagging between piles may consist of
untreated timber or precast panels. Permanent Soldier pile walls with
exposed timber lagging is not permitted. The top of sheet pile walls will be
encased in a concrete cap.
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iii. Sheet Pile and Soldier pile and lagging walls may be designed using
tiebacks or ground anchors. Tiebacks will be located a minimum of 5 ft.
below the top of rail. Tieback wall design and construction will conform to
FHWA RD-82-046, FHWA RD- 82-047, and FHWA-IF-99-015 for ground
anchors. Anchors will be encapsulated with plastic sheathing. Proof load
tests and verification (performance) tests for anchors will be provided in
accordance with the specified FHWA guidelines.
iv. All tie-backs, where permitted, will remain within Project right-of-way.
E. The following retaining wall types are prohibited: mechanically stabilized
earth retaining wall, timber retaining wall, masonry retaining wall, retaining
wall with tie-backs that incorporate a deadman anchorage system, soil nailed
and helical screw anchored walls.
4.6.5.4.2 Existing LBMM Retaining Walls
A. Overview: The existing retained embankment in the LBMM section of the
Project is bounded on the east and west sides by a system of concrete
retaining walls. This system consists of concrete gravity, semi-gravity,
reinforced concrete cellular type and reinforced concrete tee wall sections. At
both sides of the viaduct abutments, between the abutment stem and the
retaining walls, are cast in place wingwalls. The wingwalls are perpendicular
to the viaduct abutments and parallel and in-line with the retaining walls. A
ballast curb with an encased clay tile duct bank forms the upper portion of the
retaining and wingwalls.
There are approximately 513 retaining wall panels that form the east and
west sides of the embankment between the limits of Leland Avenue and
Thorndale Avenue. The typical gravity and semi-gravity wall section is 25 ft.
long. The typical reinforced concrete cellular type wall section is
approximately 30 ft. long. Overall retained height varies along the corridor but
is generally on the order of 15 ft. to 16 ft.
B. Wall Modifications: The existing embankment and retaining walls are to be
modified in accordance with the following:
i. Final finish elevation of the existing retained embankment will be a
minimum of 7 ft. below bridge longitudinal framing elements. The top of
existing walls and abutments will be reconstructed to an elevation no
greater than 6 in. above the final adjacent retained embankment. The top
of the lowered wall requires a new, reinforced, cast-in place concrete cap
with a minimum thickness of 12 in. The cap must extend the full width to
cover the entire top of wall, front face to back face. Where the existing
west retaining wall is abutting and in direct contact with an existing
adjacent property structure or building, the wall will remain as-is.
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ii. Retaining wall removals as required to facilitate new and Temporary
station facilities and auxiliary structures.
iii. Portions of retaining walls and or abutments that are not required to be
removed for construction of new facilities may be removed for the
purposes of Contractor’s means and methods as required for
embankment access. New reinforced concrete walls will need to be
designed and constructed in the areas where abutments and walls had
been removed.
iv. Repair and reconstruct portions of the existing retaining walls as required
to support miscellaneous structures, including messenger poles and
wayside platforms required to support ancillary systems or CSI
infrastructure extending north to the CSI project limit of improvements.
v. Repair and reconstruct elements of the existing east gravity walls
between Ardmore and Thorndale in advance or in conjunction with the
pre-stage construction of the Thorndale Interlocking will include the
following:
Top of wall: Removal of the existing clay tile duct bank and full
reconstruction of the ballast curb between the end of the proposed
structure abutment north of Ardmore to the south Thorndale viaduct
abutment.
Design and construct as required to retrofit and stabilize or replace
Panels 22-AT through 24-AT. These three panels currently show out
of plane measurements of 2 percent to 2.3 percent.
C. Existing Retaining Wall Assessment:
i. All existing walls affected by Contractor’s means and methods that apply
loads to the structure or change its structural behavior will be assessed
and evaluated. Refer to Sub Part 4.6.7.2 for Structural Assessment
Report requirements. The condition of the existing wall will be considered.
ii. Contractor will verify that stability factors of safety for the existing walls
are in accordance with the following criteria:
Factor of Safety against Overturning > 1.5
Factor of Safety against Sliding (Stem/Footing Interaction, Gravity
Wall Type Only) > 1.5
Factor of Safety against Sliding (Footing/Soil Interaction) > 1.5
iii. The Temporary Works Structural Engineer is responsible for review and
approval of all Temporary work that may be required to stabilize or repair
the existing retaining walls as required to support Contractors means and
methods loading.
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D. Existing Retaining Wall Repair and Rehabilitation
i. Tier 1 Repairs: Tier 1 repairs are Temporary, advance repairs to the
system of existing retaining walls and wing walls along the west side of
the LBMM embankment that will be installed pre-stage, prior to
implementing the second LBMM phase construction that takes tracks 3
and 4 out of service. Tier 1 repairs will stabilize deteriorated and/or
structurally deficient sections or areas of the walls. The advance repairs
focus on elements that need to be stabilized or repaired as required to
assure adjacent tracks will not be rendered out of service due to wall
element failure and include the following:
Stabilization of the existing abutment returns / wing walls.
Reconstruction of the existing retaining wall ballast curbs as required
to maintain containment of track ballast during the initial LBMM phase
construction.
Tier 1 repair locations and details are specified in the report, CTA
Retaining Walls Leland to Thorndale, Existing Condition Report, located
in Appendix 4N. Tier 1 repair locations are located in Appendix C of the
report and are labeled as E1, E1-R, E2 or 2B. Associated repair details
are located in Appendix E and F of the report or (subject to Sections 4.3
and 8.4.d of Part 1) as modified by Part 1, Exhibit 1, ATC 20.0 – LBMM
Ballast Curb Repair.
ii. Tier 2 Repairs: Tier 2 repairs are Permanent repairs to portions of
existing retaining walls and abutments in the final condition. Contractor
will inspect and document the condition of the existing retaining walls and
abutments in order to develop repair and restoration work in conformance
with the 25-year service life requirement and all mandatory standards.
Repair details include crack repair (crack widths ≥ 0.07 in.), cast-in-place
and high performance shotcrete repairs (for spalled and delaminated
concrete), restoration and or replacement of existing reinforcing steel and
potentially full panel replacement. Panels with existing wall repairs (steel
plates, stabilization beams, etc.) will be rehabilitated such that all external
repairs can be removed for the final condition.
Tier 2 repairs also include complete replacement of all abutment return/
wing wall stems that remain in the final condition. The new walls will
include provisions for expansion and waterproof joint detail between the
wing wall and the adjacent existing retaining wall.
The CTA has performed an advance inspection of the retaining walls in
an effort to develop base line Tier 2 repair quantities for the walls.
Estimates for repair quantities are found in the “Condition Retaining Wall
Searchable Database” in Part 7. Repairs to retaining walls identified in
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Appendix 4N, Exhibits 1-8 as “Not Inspected-abutting building”, are
inaccessible and will not be required.
4.6.5.5 Miscellaneous Structures
4.6.5.5.1 CCTV Camera Structures
A. The analysis, design and construction of CCTV camera support structures,
mounting apparatus and lowering devices will conform to the following
criteria.
B. The design will be in accordance with the AASHTO Standard Specifications
for Structural Supports for Highway Signs, Luminaires, and Traffic Signals.
The design wind speed to be used in computing design wind pressure for all
parts of the structure will be as shown in the design specifications with a
minimum wind speed of 90 mph. The pole will meet design wind loading with
camera(s) installed. The design loading will include the requirements of Sub
Part 4.6.4.13.
C. The Design Life will be 50 years for all CCTV camera support structures.
D. The effective projected area (EPA) of the fixture and mounting arm will be
cross referenced in the calculations. Pole deflection will not exceed 0.7 in. in
30 mph wind or 1.4 in. in 70 mph wind, unless the installed camera’s
specifications have a more stringent criteria.
E. The natural frequency of the installed pole will be outside the critical wind
velocity (Vc) range as determined by design. Fatigue design will conform to
Fatigue Importance Category I and include wind-induced harmonic
resonance. Calculations and detailed drawings will demonstrate compliance
with the AASHTO specification and will be submitted to the CTA as a part of
the Design Submittal for the Design or Work Package containing this
element.
F. The camera lowering device will be electric and designed to support and
lower a closed circuit television camera, lens, dome type housing, PTZ
mechanism, cabling, connectors and other supporting field components
without damage or causing degradation of camera operations. If required,
pole vibration will be controlled by non-mechanical means and the aesthetics
will be required to be reviewed by the CTA.
G. CCTV cameras will not be mounted to light poles or other structural elements
unless reviewed by the CTA. Hinged poles will not be allowed.
H. All poles, mounting apparatus, and camera lowering devices will be
constructed of hot dipped galvanized steel. CCTV technical requirements to
provide the required camera quality. Electrical isolation base pads will be
installed underneath all base plates.
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4.6.5.5.2 Cable Trays
The minimum criteria for cable trays will be:
A. Cable trays and accessories will conform to NEMA Standard VE 1 and be hot
dipped galvanized after fabrication.
B. Cable trays will be of the ventilated, steel ladder type with 9 in. rung spacing.
Tray width and depth will be as required. All components of the tray systems
including connection hardware will be of the same design and manufacture
throughout the project. Fittings in cable tray system will have a minimum
radius of 24 in. for both vertical and horizontal runs.
C. Cable trays will have a minimum load rating of 50 plf. with a safety factor of
1.5 at 12 ft. support span.
4.6.5.5.3 Equipment and Wayside Platforms
A. Equipment and wayside platforms, where required, will be designed and
constructed similar to the materials of the adjacent track structure in which
they are attached to. The minimum dead and live loading on platforms will be
in accordance Sub Part 4.6.4.10. Elements will be designed in accordance
with AREMA; and the bolted connections will have a minimum of three bolts.
B. At rail lubricator platforms located on open deck structures:
i. Platforms will only be placed within the outer one-third of a span and will
not straddle an expansion pier/bent.
ii. Drip pans will be installed beneath the platform, over sidewalks and
egress routes in the direction of train travel adjacent to the rail lubricator
platform until the wipers and a minimum of 5 ft. beyond the lubricator.
4.6.5.5.4 Underground Vaults
A. Stormwater and other vaults will be designed in accordance with the
requirements of the AASHTO LRFD Bridge Design Specifications, Section 12
and Part 4.5, Drainage Systems.
B. Construction loads and staging will be included in the design of the
structures.
C. Contractor will design vaults for buoyancy under high water table conditions.
For water-containing vaults, this requirements includes the condition where
all water has to be removed in order to repair the structure (i.e., vault is
empty). Design against flotation will include the appropriate self-weight of the
structure and/or CTA reviewed tie-downs appropriate for soil conditions,
including construction scenarios.
D. Hatches, lids, covers and risers for vaults and other buried structures will be
designed for a 16,000-lb. wheel load (or greater, based on construction
equipment to be used), with increased impact as a deck joint at the critical
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location (AASHTO LRFD Bridge Design Specifications, Table 3.6.2.1-1), in
addition to the appropriate soil and live load lateral pressures. These loads
will be transferred to the vault structure with HL-93 loading distributed through
the appropriate soil depth. Lids will be tamperproof.
E. All joints will be sealed; and joints will not allow differential movement which
is detrimental to required use of the structure.
F. The size, type, and location of vaults will be determined and approved by the
corresponding subject matter parts of the technical requirements.
4.6.5.5.5 Construction Barrier (Track Separation Fence)
A. A construction barrier will be placed to isolate construction areas and stations
from adjacent, active/in service tracks. Further discussion is presented in Part
3.10.
B. The construction barrier will be designed to resist a horizontal wind pressure
of not less than 30 psf. The construction barrier is not intended to provide fall
protection at required locations. However, depending on Contractor’s means
and methods, the design will include these provisions where necessary.
C. Construction barrier details and layout will be submitted to CTA as a Design
Submittal.
D. Posts spacing will be 8 ft. maximum and the bottom 6 ft. of the construction
barrier will be a material with no openings larger than 2 in. square.
E. Posts, barrier fence, and visual screen will be constructed from non-
conductive materials. Wood, if used, will be pressure treated in accordance
with AWPA U1, User Category UC4B or UC4C.
F. For installation on new or existing closed deck concrete structures, all anchor
inserts and fasteners will be stainless steel. The anchor system must be
detailed for removal of fasteners. Fastener holes will be filled with high
strength non-shrink grout or other material that is compatible with the
durability and service life requirements for new reinforced concrete decks.
G. For installation in existing track ballast and subgrade, post ground anchors
will be designed and installed in a manner that minimizes disturbance of the
ballast and subgrade along the tracks. Top of ground anchors will be set a
minimum of 4 in. below existing ballast grade and backfilled to match existing
grade.
H. A mock-up post installation for each type of application will be required to
evaluate the adequacy and performance of the design. A design load will be
applied to the bottom of the post and the deflection at the top of post will be
measured. The design load will be submitted to CTA as a Design Submittal.
The deflection at the top of post will be measured.
I. If the ground anchor shifts out of position or the post deflects greater than 1
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in. at the top, the mock-up installation and load test will be repeated with the
embedment depth of the post/anchor adjusted until the load test results in a
successful test that meets the required deflection criteria. Installation on new
or existing decks will also be load tested to satisfy the deflection criteria.
4.6.5.5.6 Abandoned Sewer
A. The 8.5 foot diameter abandoned sewer on Lawrence Avenue near the
Lawrence station will be backfilled. See Part 3.1 for limits of work.
B. Prior to backfilling, clean the area of the pipe of debris that may hinder fill
placement. Remove any free water prior to fill placement.
C. Backfill material will consist of Controlled Low-Strength Material.
D. Place bulkheads to contain the backfill material within the limits of work.
Continuously place the backfill material to fill the volume between the
bulkheads as completely as practical.
4.6.5.6 Temporary Structures
4.6.5.6.1 General
A. Temporary structures are to be designed, constructed, tested, inspected,
monitored and held to the same requirements and level of quality control as
the Permanent structure. Temporary structures are to be planned with all
staging and phasing activities scheduled by Contractor to execute the work.
Contractor will accommodate all requirements of CTA’s Adjacent
Construction Manual, included as Appendix 4M.
B. Chicago’s Department of Transportation and its Office of Underground
Coordination requirements apply to all Temporary structures used on the
CTA's system or within the public right-of-way.
C. Temporary structures not necessarily outlined herein may include
requirements for the construction of deep foundations and protection of
existing facilities, whether owned by the City of Chicago, CTA or another
private or public entity.
D. Temporary structures will have positive connections between individual
elements within the overall system. Temporary structures will be safe and
stable structures independent of other existing or proposed structures, unless
required otherwise. Temporary structures within the public right-of-way will be
protected for users of non-CTA facilities.
E. Load transfers from one structure type to another structure will be completed
with only dead loads on the affected members and systems. When loading or
unloading of Temporary structures is required, load transfer procedures will
be described and detailed in the appropriate Temporary structure Design
Submittals.
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F. Design criteria specified in Part 4.3, Geotechnical will be applied to the
analysis, design and construction of Temporary foundations and earth
retaining structures necessary to complete the Project. The design of earth
retention systems will assume that the water table is 4 ft. higher in elevation
than what is noted in the final geotechnical report prepared by Contractor.
G. Contractor will prepare shop drawings and calculations in accordance with
Sub Part 4.6.7.
H. Contractor will be responsible for inspection and maintenance of Temporary
structures per Part 5. Contractor will create a checklist and inspection
protocol to document that the Temporary structures are installed per design
drawings. Records will be made available to CTA.
4.6.5.6.2 Temporary Elevated Track Structure
A. “Temporary bridge” hereinafter refers to any bridge or portion of a bridge that
will not remain upon completion of the Contract.
B. All Temporary bridges that carry elevated track loads will be designed as
Permanent structures in accordance with Part 4.6 for loading and
performance but they will not be required to be galvanized or finish painted.
Steel framed Temporary bridges require a shop coat of paint to prevent rust
from staining other parts of the work or other adjacent appurtenances. Epoxy
coated reinforcement will not be required for Temporary concrete elements.
C. Components of Temporary bridge structures which will be incorporated into
the Permanent structures will meet all requirements for Permanent bridge
structures, including materials, coatings and finishes.
D. Unless otherwise indicated in the RFP, deep foundations designed in
accordance with the requirements for Permanent structures are required
except (subject to Sections 4.3 and 8.4.d of Part 1) as modified by Part 1,
Exhibit 1, ATC 05.0 and 05.1 – Spread Footing at Temporary Bridge and
Clarifications.
E. Contractor may widen existing bridge structures temporarily, when required.
The Temporary widened portion will meet the requirements for Temporary
bridge construction.
F. Design plans and specifications for all Temporary bridges will be reviewed
and approved by the Temporary Works Structural Engineer. Prior to opening
to traffic, all Temporary bridges will be reviewed in the field for compliance
with the plans and specifications by the Temporary Works Structural
Engineer and a memorandum prepared of this inspection which will be
retained by Contractor and available for inspection by CTA.
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4.6.5.6.3 Requirements for Temporary Earth Retention Systems
A. The type of Temporary earth retention system selected by Contractor’s team
is required to be independently stable. The following type of earth retention
are prohibited: micropiles with lagging, slurry walls, soil nailed and helical
screw anchored walls or a system requiring tiebacks with deadman system
for support.
A. Earth Retention Systems installed adjacent existing buildings or residences
will be designed to limit deflection of the Temporary earth retention system to
a maximum of 1/4-in. Prior to installing the system and excavating, Contractor
will perform a survey of the existing buildings within the zone of influence of
the system and document any existing cracking, deterioration and/or
displacement of any building members. At a minimum, Contractor will
monitor, on a daily basis the horizontal and vertical location of the Temporary
earth retention system. Identification of any movement greater than 1/4-in.
will be immediately brought to the attention of the CTA. Contractor will
investigate the cause of the movement, propose correction/repair options for
CTA comment and begin the repair as soon as possible but no later than 24
hours after being identified. All monitoring and inspection will be coordinated
with Part 4.2 and all other requirements of the RFP.
B. Structural components of Temporary retaining walls may be reused as part of
Permanent retaining wall systems, provided all of the structural support
elements and materials of the Temporary retaining walls meet the
requirements for Permanent walls noted elsewhere.
C. Temporary retaining walls may be abandoned and left in place by Contractor
on the condition that the Temporary walls are no longer required for ground
support, or that Permanent retaining walls are constructed to replace them or
as discussed herein. Unless otherwise directed, Contractor will remove the
remaining portion of the Temporary retaining walls to a point no less than 2 ft.
below finished ground, adjacent ground or pavement section. Temporary
retaining walls or components thereof, constructed of treated timber will be
removed entirely. Temporary retaining walls constructed outside of CTA right-
of-way must be removed in their entirety. Temporary walls and sheeting
abandoned within the CTA right-of-way must be accurately depicted on as-
built drawings.
4.6.5.6.4 Temporary Shoring
A. Design requirements in this Sub Part are applicable to Temporary shoring of
existing structure. Design requirements herein are to be limited to specific
applications where construction staging or Contractor’s means and methods
require a limited scope of Temporary shoring and a maximum in-service
duration of six months for supporting rail vehicle live load. Temporary shoring
towers may be supported by shallow foundations if they meet the six-month
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maximum in-service duration requirement. Temporary shoring towers
supporting rail vehicle live load for more than six months will be founded on
deep foundations designed in accordance with the requirements for
Permanent structures, noted elsewhere.
B. Temporary shoring that supports live loads will be designed in accordance
with this Sub Part for permissible materials, loading and performance. Steel
elements will not be required to be galvanized or painted, unless noted
otherwise, elsewhere in this Sub Part. There will be no allowable increases in
design stresses for Temporary shoring.
C. Structures to be supported by Temporary shoring towers for any duration will
be surveyed for base line data prior to transferring load to the Temporary
elements. After loading the Temporary elements, the structure will be
surveyed daily and compared to the original baseline. Any settlement of 1/4-
in. or greater will be reported immediately to the CTA, verbally or in writing,
and corrected within 24-hours of notification. Shoring towers will be designed
and detailed to provide a quick and efficient means of jacking and shimming
as required to re-establish baseline track level elevations.
4.6.5.6.5 Underpinning
A. All designs for support and underpinning of existing structures will conform to
the requirements of the design codes applicable to that type structure, and
the local jurisdiction if applicable. The economics and feasibility of various
underpinning and dewatering methods for structures influenced by
construction of the transit facilities will be investigated and the method best
suited to a particular structure will be designed and constructed.
B. Contractor’s design and construction documents will contain specific
provisions requiring Contractor to maintain, protect and be responsible for the
safety, stability and integrity of all buildings and other structures that might be
affected by Contractor's work.
4.6.6 Material and Construction Criteria
4.6.6.1 General
All materials, which are not listed below, required for track and miscellaneous structures
will conform to the requirements of the codes and standards Sub Part 4.6.2.
All construction activities will be performed in a manner such that there will be no impact
to adjacent facilities including, but not limited to, track structures, buildings, utilities and
public infrastructure. Monitoring of facilities-existing, Temporary and Permanent-will be
required by Contractor; and the Lead Bridge Structural Designer will determine the
allowable movements, due to construction activities, of adjacent facilities.
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4.6.6.2 Reinforced Concrete
A. Reinforced concrete for structures will conform to the requirements of this Sub
Part and the design codes and loading as specified in Part 4.6, unless specified
otherwise herein.
B. Unless indicated otherwise in these documents, all concrete used in track
structures and retaining walls will be High Performance Concrete except as
noted for drilled shafts. Concrete for drilled shafts, 4 feet or lower below finish
grade, will have a minimum 28 day compressive strength of f’c = 4,000 psi.
Drilled shaft concrete above this elevation will be High Performance Concrete or
a minimum 28 day compressive strength of f’c = 5,000 psi concrete.
C. Cast-in-place concrete for non-elevated track structure application will have a
minimum 28 day compressive strength, f’c = 5,000 psi.
D. Reinforcement bars will be epoxy coated conforming to ASTM A615 or A706,
Grade 60 all sizes, deformed bars. Epoxy coating will be per ASTM A775.
E. Un-coated reinforcement bars will be permitted in the following case: In drilled
shafts when the top of drilled shaft is at least 4 ft. below finish grade or (subject
to Sections 4.3 and 8.4.d of Part 1) as modified by Part 1, Exhibit 1, ATC 01.3 –
Precast Segmental Box Girder Clarifications and ATC 17.0 – Precast
Prestressed Concrete Beam Superstructure at North Mainline.
F. Severe exposure conditions will be used to determine reinforcement distribution
requirements. Reinforcing bar detailing will be in accordance with ACI 318 and
ACI 315 or as indicated below.
G. Shrinkage and temperature reinforcement for concrete structures will be
designed, but not limited to, the requirement of AREMA Chapter 8, Section 2.12
or AASHTO LRFD Bridge Design Specifications Section 5.10.8, as required by
Sub Part 4.6.2.
H. Crack control reinforcing in the layer closest to the tension face will be in
accordance with, but not limited to, AREMA Chapter 8, Section 2.39 for severe
exposure or AASHTO LRFD Bridge Design Specification Section 5.7.3.4 for
Class 2 exposure, as required by Sub Part 4.6.2. Additional reinforcement will be
provided for crack control at openings in concrete structures.
I. Unless otherwise indicated in the RFP, reinforcing steel clear cover will be
detailed in accordance with the following:
i. Cast-in-place concrete: clear cover will be 2 in. unless noted otherwise.
ii. Cast-in-place concrete against earth: clear cover will be 3 in.
iii. For elevated track structure closed deck slabs, clear cover to the top layer of
reinforcement will be 2½ in.
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iv. Precast concrete – clear cover will be 1½ in for precast elements not directly
supporting rail vehicle loads.
4.6.6.2.1 High Performance Concrete
A. High Performance Concrete (HPC) will exceed the performance of normal
concrete for durability, mechanical and construction properties required for
the specific elements, e.g. deck, columns and caps. HPC will be designed
and constructed by properly accounting for the environmental conditions
during installation and the service life of the element.
B. The purpose for HPC in this project is to obtain a 100 year service life for
each element HPC is constructed with. The HPC mixes used within this
Project will be performance based, demonstrated thru testing and proven in
construction. While all the parts of a determining a quality concrete mix are
important, the performance of each element over its life depends on the
complete implementation including quality management.
C. All of the specific HPC mixes used by Contractor will include; the
requirements for materials, methods for proportioning, mixing, transporting,
placing, finishing, curing, quality control and assurance of each concrete
element.
D. In addition to the laboratory tests required for the materials and mix
proportions, Contractor will be responsible for providing field trial batches and
a full scale mockup of each HPC element to be utilized in the Project. No part
of any mockup will be implemented or integrated into the Permanent or
Temporary structures.
E. Trial batches will be constructed and cured at all anticipated field conditions.
If during the Project, material substitution is required; only verified mixes with
approved trial batches and a mockup will be allowed.
F. The required mock ups will be constructed identical to those required for each
proposed element to verify all techniques to be used for transport, placement,
consolidation, finishing, and curing of the concrete member are satisfactory.
All testing during and preceding the construction of the mock ups will be
documented and provided within the report required in Sub Part 4.6.4.1.
4.6.6.2.2 Joint Requirements
Unless otherwise specified herein, expansion joints, construction joints and
contraction joints will be in accordance with AREMA Chapter 8, Section 1.11.
A. Expansion Joints
i. To control shrinkage stresses in concrete walls and to minimize cracking,
a unit length of 90 ft. or less between expansion joints is required.
Expansion joints in wall construction will also require a waterstop in
accordance with AREMA.
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ii. Maximum length between cast-in-place concrete barrier expansion joints
is limited to 20 ft. Contractor will consider additional joint spacing
requirements to control cracking in the barriers in the negative moment
areas over and adjacent to intermediate fixed supports.
B. Construction Joints – To control shrinkage stresses in cast-in-place
walls, construction joint spacing will be no more than 30 ft. Construction
Joints will be in accordance with the following requirements:
i. Construction joints will only be allowed at locations specifically
detailed on Contractor’s approved design plans
ii. For the closed deck, longitudinal construction joints are limited to
that required between stages.
C. All construction joints will be bonded. All joint locations will be shown on the
plans, and their location will be confined, as far as possible, to regions of low
shearing stress and whenever possible, to locations that will be hidden from
view. Longitudinal construction joints will be placed in the middle half of the
bay between stringers and will not cross a beam line. The reinforcing steel
will extend through such joints. Shear keys, formed into or out from the
surface of the previously placed concrete or steel dowels, will be used where
required. The face edges of all joints which are exposed to view will be
carefully finished true to line and elevation and compliment the aesthetic
surface treatment described in Part 3.2.
D. For bonded constructions joints to hardened concrete, the existing cement
paste will be removed to create a prepared surface. The surface will be
cleaned by abrasive equipment such as sandblasters, shotblasters, or high-
pressure waterblasters to expose clean, well bonded aggregate, remove
unsound concrete or laitance layers, and mitigate the surface microcracking
(sometimes called bruising) common when impact tools are used to remove
concrete.
E. The cleaned prepared surface of the existing concrete will be wetted, with
potable water, a minimum of one hour before application of the new concrete.
The surface will be maintained in a dampened condition during that period.
Immediately before placing the new concrete, the concrete will be saturated
and surface dry; any excess water will be removed.
F. For further clarification and requirements of the surface preparation of
concrete construction joint preparation, reference will be made to ACI 546-14
and ICRI Guideline No. 310.2R-2013.
4.6.6.2.3 Finish
A. Concrete surface finish, unless otherwise noted, will be in a normal or rubbed
finish as described herein. A rubbed finish will be provided at all exposed
station walls, substructure elements in and at the stations; and on exterior
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station walls the rubbed finish will extend to the interface between the new
walls and the existing retaining walls. A normal finish will be provided at all
other new concrete elements, except as noted herein.
B. Normal finish will consist of the removal of fins, rough spots, stains, hardened
mortar or grout, and form lines by rubbing with a No. 16 carborundum stone
or an abrasive of equal quality with materially changing the texture of the
surface. The rubbing will be continued sufficiently to produce a surface
matching the surrounding surface.
C. When the surface of concrete shows a film of oil left from an excess of oil on
the forms, or the concrete is oil-stained, or is otherwise not of uniform color,
the Contractor may be required to employ the following cleaning method. Mix
one part cement and 1 1/2 parts fine sand with sufficient water to produce a
grout having the consistency of thick paint. Cement from the source of the
cement used in the concrete will be used in the grout. Wet the surface of the
concrete sufficiently to prevent absorption of water from the grout and apply
the grout uniformly with brushes, completely filling air bubbles and holes.
Immediately after applying the grout, float the surface with a suitable float,
scouring the wall vigorously. While the grout is still plastic, the surface will be
finished with a sponge rubber float removing all excess grout. This finishing
will be done at the time when grout will not be pulled from holes or
depressions. Next, allow the surface to dry thoroughly, and then rub the
surface vigorously with dry burlap to completely remove any dried grout.
There will be no visible film of grout remaining after this rubbing. The entire
cleaning operation for any area will be completed the day it is started. No
grout will be left on the wall overnight. No cleaning operations will be
undertaken until all patching and filling of tie holes has been done.
D. Rubbed finish will require that the surfaces will be thoroughly wet with a brush
and rubbed with a No. 16 carborundum stone, or an abrasive of equal quality,
bringing the surface to a paste. The rubbing will be continued sufficiently to
remove all roughness and projections, producing a smooth dense surface
free from pits and irregularities. The material which has been ground to a
paste in the above process will be carefully spread or brushed uniformly over
the rubbed surface and permitted to reset. The final finish will be obtained by
a thorough rubbing with a No. 30 carborundum stone, or an abrasive of equal
quality, first wetting with a brush as for the initial rubbing. The finish rubbing
will continue until the entire surface is of a smooth texture and uniform in
color.
E. Saw cut grooving of concrete decks will not be required.
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4.6.6.2.4 Concrete Sealer and Coating
A. Unless noted otherwise in these technical requirements, concrete sealer will
be applied to all exposed surfaces of new concrete elements. These
elements include but are not limited to the following:
i. All exposed surfaces of new concrete substructure elements. This
requirement will include elements such as: abutment stems, abutment
backwalls, columns, caps, pedestals and bridge seats.
ii. All new retaining walls.
iii. The top surfaces of all closed concrete decks.
iv. The exterior face of all closed concrete decks.
v. Direct fixation concrete plinths (where they are not covered by plating
associated with the rail direct fastening system).
vi. The top and both vertical faces of all noise barriers.
The underside (soffit) of the closed concrete deck is not required to be
sealed.
B. The concrete sealer will be water based, odorless, colorless; that penetrates,
hardens and densifies concrete surfaces and leaves a nondarkening film that
protects the concrete surface from oil, water, grease, dirt, and chloride-ion
penetration. Sealer will be able to be applied in horizontal and vertical
applications, compatible with any concrete admixtures, color stains, curing
compounds, hardeners, and any other concrete treatments used. Sealer will
meet current local, state and federal VOC restrictions and be non-flammable.
C. A pigmented sealer will be applied to all exposed surfaces of the existing
retaining walls and the existing abutments or new closure walls at the non-
station viaducts. The sealer will also be applied to the entire surface of the
new concrete wall cap.
D. An anti-graffiti coating will be applied to all exposed concrete surfaces of
retaining walls; abutments; columns; column pedestals; bent caps; exterior
face of closed concrete decks; the top and both vertical faces of all noise
barriers; and, all other concrete elements which could reasonably receive
graffiti. The underside (soffit) of the closed concrete deck is not required to
receive an anti-graffiti coating. Contractor will provide an anti-graffiti coating
that is fully compatible with the required concrete sealers.
4.6.6.2.5 Anchorage Requirements
Concrete anchors can be either cast-in-place or post-installed anchors. Post-
installed anchors typically fall into two main groups – adhesive anchors and
mechanical anchors. Adhesive anchors installed in the overhead or upwardly inclined
position and/or under sustained tension loads are prohibited. The design of concrete
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anchors will be in accordance with ACI 318. Minimum spacing, edge distances and
minimum thickness of members will be in accordance with ACI 318. Concrete
anchors will be stainless steel or hot-dipped galvanized.
4.6.6.3 Joint Seals for Bridge Deck Joints
A. Preformed elastomeric seals for preformed elastomeric strip seals and modular
expansion joints will be according to ASTM D 5973. The preformed elastomeric
strip seal will have a shallow “v” profile and will contain “locking ears” that form a
mechanical interlock when inserted in the steel locking edge rails. The size of the
seal will accommodate the rated movement shown on the plans.
B. The lubricant adhesive used with the seals will be according to ASTM D4070.
4.6.6.4 Drilled Shafts
Corrugated metal liners will be provided full length for all drilled shafts, except (subject to
Sections 4.3 and 8.4.d of Part 1) as modified by Part 1, Exhibit 1, ATC 11.0 – Drilled
Shafts: Eliminating the CMP Liner Requirement; and the length will be from the ground
surface to 2 ft. above the base of the shaft or the top of the bell for belled shafts. In place
lengths will vary due to actual top of shaft elevations. Corrugated liners may be delivered
in any convenient sections with sections connected in accordance with the
manufacturer’s instructions. Use of Temporary and Permanent casings will be as
determined by the Lead Geotechnical Engineer in the Foundation Design Reports as
indicated in Sub Part 4.3.5.4.
4.6.6.5 Structural Steel
A. All steel elements subject to any type of rail vehicle live loads will be ASTM A709
Grade 50. Acceptable materials for Structural Steel elements not subject to direct
rail vehicle live load include; ASTM A36, ASTM A572 Grade 50 and ASTM A992.
B. Main load carrying components, including but not limited to flanges, webs and
splice plates subject to tensile stress designated as Notch Toughness
Requirement (NTR), will conform to the requirements of the AREMA Manual
Chapter 15 Section 1.2.1 for Zone 2 and the AASHTO LRFD Bridge Design
Specifications for Section 6.6.2, Zone 2 at the Red-Purple Bypass structure.
C. Members designated to be fracture critical member (FCM) and repair elements
for existing FCMs will conform to the requirements of AREMA Manual Chapter
15, Section 1.14 Steel Structures for Zone 2 service. At the Red-Purple Bypass
structure, FCMs will conform to the requirements of the AASHTO LRFD Bridge
Design Specifications for Section 6.6.2, Zone 2.
D. All high strength bolts, nuts and washers will be hot dipped galvanized in
accordance with ASTM A153.
E. All new structural steel will be hot-dip galvanized. Member sizes greater than 75
ft. in length, within the limits of the closed deck structure, are not exempt from
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meeting this requirement. The longer members may need to be designed and
detailed to incorporate additional splices in order to meet the galvanizing
requirement; a maximum number of two splices per span will be acceptable
when the span length exceeds 75 ft. The shear studs will be welded to the top
flange prior to galvanizing or in the field. Top flanges which will receive field
installed shear stud connectors will not be galvanized within 2 in. of the stud
location(s). Either the entire area receiving studs or just individual stud locations
may be left ungalvanized. Where installation of shear stud connectors is to occur
in the field, the edges of the top flange will have a minimum of ½ in. of hot-dip
galvanizing coverage along the entire perimeter of the top flange.
F. Damaged hot-dip galvanized coatings will be repaired in accordance to the
requirements of ASTM A780 and as reviewed by the CTA.
G. Structural steel used for the rehabilitation and modification of the existing RPB-
NM or RV structures is exempt from the hot-dip galvanizing requirement and will
be painted.
H. Anchor bolts for elevated track structure applications will conform to ASTM
F1554 and will be galvanized in accordance with ASTM A153.
I. Contractor will prepare an erection plan for the proposed erection of the
structural steel as part of the Construction Process Plan Administrative
Submittals as described in Part 2.5.
J. The erection plan will be complete in detail for all phases, stages, and conditions
anticipated during erection. The erection plan will include structural calculations
and supporting documentation necessary to completely describe and document
the means, methods, Temporary support positions, and loads necessary to
safely erect the structural steel in conformance with the contract documents and
as outlined herein. The erection plans will address and account for all items
pertinent to the steel erection including such items as sequencing, falsework,
Temporary shoring and/or bracing, girder stability, crane positioning and
movement, means of access, pick points, girder shape, permissible deformations
and roll, interim/final plumbness, cross frame/diaphragm placement and
connections, bolting and anchor bolt installation sequences and procedures, and
blocking and anchoring of bearings.
K. Contractor will be responsible for the stability of a partially erected steel structure
during all phases of the steel erection until the structure is completely assembled
and detailed. When the duration of the work impacts CTA operations then a
schedule of activities with time durations will be included with the erection plan.
L. Additional requirements regarding the construction of the curved steel structure
includes the casting of the concrete deck and barriers, are found in AASHTO (3rd
edition with all interim revisions) LRFD Bridge Construction Specifications,
Section 11: Steel Structures, Article 11.8 – Additional Provisions for Curved Steel
Girders.
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4.6.6.6 Steel for Casings and Piles
A. Pipe used for micropiles will be API oil field casing Grade N-80, 5CT N80 with a
minimum diameter of 7 in.
B. Permanent sheet piling will be according to ASTM A572, Grade 50 minimum.
C. Temporary Sheet Piling used material may be used which will be identifiable and
in good condition, free of bends and other structural defects. The minimum yield
strength will be 38.5 ksi.
4.6.6.7 Dissimilar Materials
Aluminum will not be allowed to come into contact with concrete. Dissimilar metals are to
be isolated from one another to avoid galvanic action. Paint will not be accepted to
separate dissimilar materials.
4.6.6.8 Electrical Isolation Materials
A. All steel elements of the elevated track structure or members connected to the
elevated track structure will be electrically isolated at their interface with
supporting substructure and foundations. Repairs and renovations to existing
structures will be in accordance with this criteria to the extent feasible.
B. Isolation material will be per specification number 05 80 00 and should be
included as a bearing pad under the steel base plate, bushings around the
anchor rods going through the steel base plate and washers between the anchor
rod steel washers and steel base plate.
C. The isolation material is for use in electrical isolation (dielectric strength), shock
and vibration reduction on elevated track structures and other miscellaneous
structural applications where appropriate.
D. Alternative methods proposed to electrically isolate steel and concrete must
provide insulation resistance equal to or better than materials and methods
indicated above and per specification number 05 80 00.
4.6.7 Design Submittals
4.6.7.1 Structure Design Submittals
The CTA will review and comment on all scheduled and required Design Submittals and
will return comments to Contractor in accordance with the requirements of Part 2.
4.6.7.2 Structural Assessment Report
A. Contractor will prepare and submit, Structural Assessment Reports (SARs) as
Design Submittals at the Intermediate stage of design for proposed work on
existing and Permanent structure(s) or portions thereof. Unless noted otherwise,
a SAR will be required when Contractor’s means and methods apply loads to the
structure or change its structural behavior, including alternative loadings than
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those intended for in the final design; any revision by Contractor of the means
and methods will require resubmittal of the SAR. A SAR is required prior to
beginning the work covered by that SAR; and the SAR will be coordinated with
Construction Process Plans or other relevant submittals required in Part 2.
Separate portions of the work may be covered by separate SARs which may be
provided for different Design or Work Packages at different times or as dictated
by Contractor’s schedule.
B. Existing structure information, to the extent that information is available, will be
provided by the CTA to Contractor upon request. The availability of structural
information from the CTA is solely for the convenience and information of
Contractor and will not relieve Contractor of the duty to make, and the risk of
making, examinations and investigations as required to assess conditions
affecting the work. Any data furnished is for information only and does not
constitute a part of the Contract. The CTA makes no representation or warranty,
express or implied, as to the information conveyed or as to any interpretations
made from the data.
C. A SAR for removal of existing structures, or portions thereof, will demonstrate
that Contractor’s proposed means and methods to accomplish the Work do not
compromise the structural adequacy of the structure, or portions thereof that are
to remain in service, at any time during the work activities being performed. Each
phase of the operation will be accounted for, as well as the existing condition of
the structure.
D. A SAR for new construction or for construction utilizing existing components will
demonstrate that Contractor’s proposed means and methods to accomplish the
work do not compromise the structural adequacy of the bridge or portions thereof
at any time during the work activities being performed
E. Requirements:
i. All work specified will be performed according to the Contract plans, Special
Provisions and/or Standard Specifications governing that work.
ii. Design Submittals for individual elements but not limited to falsework and
forming for concrete construction will be according to those specifications.
iii. All SARs will detail the procedures and sequencing necessary to complete
the Work in a safe and controlled manner. Plans showing each phase and
supporting design calculations will be provided verifying the following:
The effects of the applied loads do not exceed the capacity at maximum
rating for any portions of the structure being utilized in the demolition of
the structure provided those portions are not to be reused.
The effects of the applied loads do not exceed the capacity at Inventory
level for new construction or for portions of the existing structure that are
to be reused.
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The condition of the structure and/or members has been considered.
iv. See AREMA and AASHTO Manual for Bridge Evaluation for further
information on determining the available capacities at the maximum and
normal rating.
v. The SAR(s) will be prepared and sealed by an Illinois Licensed Structural
Engineer and coordinated with the Temporary Works Structural Engineer.
Contractor will submit SAR(s), complete with sealed working drawings and
supporting design calculations, as Design Submittals, at least 30 calendar
days prior to start of that portion of the work.
vi. At a minimum a Structural Assessment Report will include the following:
A plan outlining the procedures and sequence for the Work, including
staging when applicable.
A demolition plan (when removal is included as an item of Work in the
contract) including details of the proposed methods of removal.
A beam erection plan (when beam erection is included as an item of Work
in the contract) including details of the proposed methods of erection.
Pertinent specifications for equipment used during the Work activity.
The allowable positions for that equipment during the Work activity.
The allowable positions and magnitudes of stockpiled materials and/or
spoils, if planned to be located on the structure.
Design and details for Temporary shoring and/or bracing, if required by
Contractor’s means and methods.
vii. Review and comments by the CTA of a Structural Assessment Report will not
relieve Contractor of any responsibility for the successful completion of the
work.
viii. Revisions to Contractor’s means and methods resulting in no increased load
effects to the structure, as determined by the Temporary Works Structural
Engineer, will not require a SAR resubmittal. However, the Temporary Works
Structural Engineer will provide CTA written verification that there is no
increased load effect as a Construction Submittal. The written verification will
specify the revisions and will be required prior to the start of the revised
activities.
ix. Contractor will be responsible for following the approved SAR related to the
work involved.
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4.6.7.3 Special Submittals
Item Part Submittal Type Initial Submittal
1 4.6.5.2.3Bridge Condition Reports:
RV and RPB-NMDesign Concept
24.6.5.4.2 C
and 4.6.7.2
Structure Assessment
Reports: LBMM Retaining
Walls and Viaducts
Design Intermediate
3 4.6.7.2
Structure Assessment
Reports: RV, RPB-NM,
others
Design Intermediate
4 4.6.4.1 Service Life Report Design Concept
5 4.6.4.6 Fracture Control Plan Design Intermediate
6 4.6.4.4Vehicle Structure Interaction
StudyDesign Intermediate
7 4.6.4.10.6Rail-Structure Interaction
ReportDesign Intermediate
8 4.6.5.2.4 Rivet Removal Procedure Design Final/IFB/IFC
top related