part 4 - technical requirements table of contents page

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



4.5.5.1 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


4.6.2.1 Track Structures

4.6.2.2 Miscellaneous Structures

4.6.3 Compliance 93


jobrien

Line

jobrien

Line

jobrien

Highlight

4.6 Right-of-Way Structures

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


4.6.5.1 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


4.6.5.6 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


4.7.3 Compliance Requirements 158


jobrien

Line

jobrien

Line

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.



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


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.



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



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



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.



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.



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



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.



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)



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



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



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.



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.



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



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.



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)∝



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.



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.



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.



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.



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



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.



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



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



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.



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



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



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



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.



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.



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.



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



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



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



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



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



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



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



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



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



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



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



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



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



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.



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.



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.



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



Appendix 4N, Exhibits 1-8 as “Not Inspected-abutting building”, are

inaccessible and will not be required.


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.



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



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



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.



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.



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



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.



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.



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.



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



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.



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



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



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.



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



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.



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.



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

part 4 - technical requirements table of contents page

Documents