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Track Design Handbook for Light Rail Transit, Second Edition (2012)

Chapter: Chapter 13 - LRT Track Construction

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Suggested Citation:"Chapter 13 - LRT Track Construction." National Academies of Sciences, Engineering, and Medicine. 2012. Track Design Handbook for Light Rail Transit, Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22800.
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Suggested Citation:"Chapter 13 - LRT Track Construction." National Academies of Sciences, Engineering, and Medicine. 2012. Track Design Handbook for Light Rail Transit, Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22800.
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Suggested Citation:"Chapter 13 - LRT Track Construction." National Academies of Sciences, Engineering, and Medicine. 2012. Track Design Handbook for Light Rail Transit, Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22800.
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Suggested Citation:"Chapter 13 - LRT Track Construction." National Academies of Sciences, Engineering, and Medicine. 2012. Track Design Handbook for Light Rail Transit, Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22800.
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Suggested Citation:"Chapter 13 - LRT Track Construction." National Academies of Sciences, Engineering, and Medicine. 2012. Track Design Handbook for Light Rail Transit, Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22800.
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13-i Chapter 13—LRT Track Construction Table of Contents 13.1  INTRODUCTION 13-1  13.2  GENERAL REQUIREMENTS—ALL TRACKFORMS 13-1  13.2.1  Project Procurement Methods 13-1  13.2.1.1  Design/Bid/Build 13-1  13.2.1.2  Construction Management-General Constructor (CMGC) 13-2  13.2.1.3  Design/Build 13-3  13.2.1.4  Design/Build/Operate/Maintain (DBOM) 13-4  13.2.2  Track Material Procurement 13-4  13.2.2.1  Owner Furnished 13-5  13.2.2.1.1  Description of Process 13-5  13.2.2.1.2  Advantages and Disadvantages to the Owner 13-6  13.2.2.2  Constructor Furnished 13-6 13.2.2.2.1  Description of Process 13-6  13.2.2.2.2  Advantages and Disadvantages to the Owner 13-7  13.2.3  Design Concept 13-7  13.2.3.1  Clarity of Drawings and Specifications 13-8  13.2.3.2  Keeping the Maintainers in Mind 13-8  13.2.3.3  Traction Power Stray Current 13-8 13.2.3.3.1  Stray Current Isolation 13-9  13.2.3.3.2  Stray Current Collection 13-10  13.2.3.3.3  Inspection of Electrical Isolation Construction 13-10  13.2.3.4  Tolerances 13-11  13.2.3.5  Special Trackwork 13-11  13.2.3.5.1  Special Trackwork Fabrication Inspection 13-12  13.2.3.5.2  Shipping, Handling, and Installation 13-12  13.2.4  Preparatory Work 13-12  13.2.4.1  Site Plan 13-13  13.2.4.2  Accessibility 13-13  13.2.4.3  Continuity of the Work 13-13  13.2.4.4  Vehicular Traffic Management 13-14  13.2.4.5  Pedestrian Traffic Management 13-14  13.2.4.6  Pre-Inspection 13-14  13.2.4.7  Baseline Stray Current Report 13-14  13.2.4.8  Contaminated and Hazardous Materials 13-14  13.2.4.9  Permitting 13-15  13.2.4.9.1  Detours 13-15  13.2.4.9.2  Fire/Emergency Response 13-15  13.2.4.9.3  Dig Safe 13-16  13.2.4.10  Scheduling/Planning 13-16  13.2.4.10.1  Risk Analysis 13-16 

Track Design Handbook for Light Rail Transit, Second Edition 13-ii 13.2.4.10.2  Survey 13-16  13.2.4.10.3  Document Control 13-17  13.2.4.11  On-Track Construction Equipment 13-17  13.2.5  Relocation of Utilities 13-17  13.2.6  Activate Detours 13-17  13.2.7  Quality Process 13-17  13.2.7.1  Developing the Quality Program 13-18  13.2.7.2  Checklists 13-19  13.2.7.3  Non-Conformance Reports 13-19  13.2.8  Reinforcing Steel (Embedded and Direct Fixation Track) 13-19  13.2.8.1  Epoxy Coated Rebar 13-20  13.2.8.2  Black (Uncoated) Rebar 13-20  13.2.8.3  Quality, Risk, and Cost 13-20  13.2.9  Rail Grinding 13-20  13.2.10  Track Geometry Verification 13-20  13.2.11  Project Close-Out 13-21  13.2.11.1  Clean-Up 13-21  13.2.11.2  Safety Certification 13-22  13.2.11.3  Documentation Retention/Storage 13-22  13.2.11.4  Project Record Documents (“As-Built” Drawings) 13-22  13.2.11.5  NCR Sign Off 13-23  13.2.11.6  Close-Out 13-23  13.3  CONSTRUCTION ISSUES FOR DIFFERENT TRACKFORMS 13-23  13.3.1  Construction Issues for Ballasted Track 13-23  13.3.1.1  Construction Concept 13-23  13.3.1.2  Construction Activities 13-24 13.3.1.2.1  Surveying 13-24  13.3.1.2.2  Handling Material 13-25  13.3.1.2.3  Underground Systems Construction 13-26  13.3.1.2.4  Placement of Subballast 13-26  13.3.1.2.5  Layout Rail and OTM 13-27  13.3.1.2.6  Spread Initial Layer of Ballast 13-27  13.3.1.2.7  Place (Bed) Cross Ties 13-27  13.3.1.2.8  Set Up Line Side 13-28  13.3.1.2.9  Gauge Track 13-28  13.3.1.2.10  Pre-Line and Clean-Up 13-28  13.3.1.2.11  Dump Top Ballast 13-29  13.3.1.2.12  Raise, Line, and Tamp Track 13-29  13.3.1.2.13  Dress and Broom Track 13-30  13.3.1.2.14  De-stress and Make Closure Welds 13-30  13.3.1.2.15  Install Insulated Joints and Other Appurtenances 13-33  13.3.1.2.16  Clearing Ballast from under the Rails 13-33  13.3.1.3  Some Lessons Learned the Hard Way 13-33  13.3.2  Construction Issues for Direct Fixation Track 13-34  13.3.2.1  Design Concept 13-34 

LRT Track Construction 13-iii 13.3.2.1.1  Plinth 13-34  13.3.2.1.2  Inserts in Invert 13-35  13.3.2.2  Rail Cant and Superelevation 13-35  13.3.2.3  Preparatory Work 13-36  13.3.2.4  Top-Down Construction (Recommended) 13-36  13.3.2.4.1  Check Guideway 13-36  13.3.2.4.2  Rail/Plate Support System 13-36  13.3.2.4.3  Handling Material 13-37  13.3.2.4.4  CWR 13-37  13.3.2.4.5  Some Recommendations on Packaging 13-38  13.3.2.4.6  Welding Rail 13-38  13.3.2.4.7  Surface Preparation 13-38  13.3.2.4.8  Setting the Track 13-39  13.3.2.5  Drill and Epoxy Method of Direct Fixation Track Construction 13-43  13.3.2.5.1  Surface Preparation 13-43  13.3.2.5.2  Scabble Concrete 13-43  13.3.2.5.3  Survey for Grout Pads 13-43  13.3.2.5.4  Pour Grout Pads to Rail Tolerances 13-44  13.3.2.5.5  Layout Hole Pattern 13-44  13.3.2.5.6  Drill Holes into Invert 13-44  13.3.2.5.7  Repair Grout Pads 13-45  13.3.2.5.8  Clean Holes 13-45  13.3.2.5.9  Mix Epoxy and Install Anchor Inserts/Bolts 13-45  13.3.2.5.10  Attaching Fasteners to Grout Pads and Setting CWR 13-45  13.3.2.5.11  Shim Rails to Elevation or Grinding the Grout Pads 13-45  13.3.2.5.12  Line and Gauge Rails 13-46  13.3.2.5.13  Thermal Adjustment 13-46  13.3.2.6  Embedding Inserts into Precast Segments 13-46  13.3.2.7  Top-Down Methodology Advantages 13-47  13.3.2.8  Lessons Learned the Hard Way 13-48  13.3.3  Construction Issues for Embedded Track 13-49  13.3.3.1  Construction Concept 13-49  13.3.3.1.1  Top Down 13-49  13.3.3.1.2  Bottom Up 13-49  13.3.3.1.3  Drill and Epoxy 13-50  13.3.3.1.4  Slab Concept 13-50  13.3.3.1.5  Tub Concept 13-50  13.3.3.1.6  Trough Concept 13-50  13.3.3.2  Preparatory Work 13-50  13.3.3.3  General Overview of Construction 13-51  13.3.3.3.1  Excavation and Drainage 13-51  13.3.3.3.2  Compaction 13-52  13.3.3.3.3  Installing Underground Electrical Conduits 13-52  13.3.3.3.4  CWR 13-52  13.3.3.3.5  Construction in the Urban Environment 13-52  13.3.3.3.6  Safety 13-53 

Track Design Handbook for Light Rail Transit, Second Edition 13-iv 13.3.3.3.7  Welding Rail 13-53  13.3.3.3.8  Setting the Track with Isolation 13-53  13.3.3.3.9  Thermal Adjustment of Embedded Rail—Required? 13-53  13.3.3.3.10  Placing Initial Concrete Only up to Base of Rail—or Not 13-54  13.3.3.4  Lessons Learned the Hard Way 13-54 

13-1 CHAPTER 13—LRT TRACK CONSTRUCTION 13.1 INTRODUCTION The purpose of this chapter is to offer discussion on procedures and topics that are relevant not only to the construction of all types of trackforms but the entire construction process in general. Many instances of unsatisfactory construction occurred in part because the designers had little or no field experience. The major focus will therefore be on the designer and particular aspects of the construction process that should be understood when designing track for a rail transportation system. This is not written as a detailed procedure for construction but rather as a primer to explain what the designer needs to understand about the construction process since details of the design can have significant effects on the cost and/or the integrity of the system. Some approaches are difficult to build and some are simple, yet they both may function in an identical manner. Track systems that are more difficult to build can also cause more problems for persons maintaining and operating the system. Designing a very complicated track system may cause premature failure since it may also be nearly impossible to build accurately. 13.2 GENERAL REQUIREMENTS—ALL TRACKFORMS 13.2.1 Project Procurement Methods There are many methods by which an owner can procure a rail transit project. This article explores the characteristics, advantages, and disadvantages of each of the procurement methods listed below. In each case, the obligations of the designer will vary somewhat. In the case of alternative project procurement methods, the track designer’s obligations may vary depending on whether he or she is employed/engaged by the project’s owner versus the constructor. Each method has a different “degree of difficulty” and different pitfalls from the perspectives of the owner, the designer, and the constructor. 13.2.1.1 Design/Bid/Build The traditional approach to producing a transit system will utilize this method. An owner, typically a transit agency but sometimes a municipality, has a vision of a rail transit line connecting two or more points. The owner hires a designer to develop that vision into 100%-complete, bid-ready plans, specifications, and cost estimates. The completed plans and specifications are publically advertised for bids, and a construction contractor or contractors are selected to actually build the project. The distinct advantage to this method is the controls it provides to ensure quality in the finished product. If the design is 100% complete prior to soliciting bids for construction, the desired finished product is generally well defined in the bid documents. The interface issues have typically been thought through, since the entire project will have gone through a comprehensive design review process. Once the design work is complete and signed off on by the owner or the end user, the bid package is developed and offered to the private construction sector to prepare a cost estimate. The bids are received, and the lowest responsive and responsible bidder is chosen to build the job. When the construction is complete, there must be a written sign-off that the project was built

Track Design Handbook for Light Rail Transit, Second Edition 13-2 in accordance with the plans, specifications, and other contract documents. “As-built” drawings are produced, and final payment is made to the constructor(s). The next step is to turn the system over to the operator, which may or may not be the same entity as the owner. The operator will test the subsystems of the transit line and then operate test trains, a process that is collectively known as systems integration testing. This process must pass certain guidelines for performance and generally must achieve a 3-month period without incident before the system can be deemed ready for revenue service. During this period, a Maintainer will be selected. Usually, but not always, this will be part of the operator’s organization. The Maintainer performs periodic inspection and maintenance activities so that the system remains within specified minimum standards applicable to and adopted by the project. Depending on jurisdictional issues, maintenance criteria may incorporate regulations and guidelines of the Federal Railroad Administration (FRA) or the American Public Transportation Association (APTA). (Note: As of 2010, the Federal Transit Administration (FTA) does not regulate maintenance of transit infrastructure and systems but instead defers such authority to the states.) No matter which entity oversees operation and maintenance, it is imperative that minimum maintenance standards are developed for the safe operation of trains. See Chapter 14 for detailed discussion of the maintenance of LRT track and trackways. There are some distinct advantages and disadvantages to the traditional design-bid-build approach. • On the plus side, the system is generally built exactly to match the owner’s requirements and the designer’s specifications provided checks and balances are in place to ensure this occurs. Another advantage is that pricing will be more competitive during the construction phase. • The major disadvantage is the length of time it takes to get from the initial planning concept to completion of the project and the commencement of revenue LRT service. It is not unusual for this to take 10 to 15 years or more. The process is linear, and therefore each step in the process must be 100% complete before moving on to the next step. As the schedule stretches, the overall cost for the full completion of the project, measured in terms of dollars at the time of their expenditure, can escalate dramatically. However, it should be noted that the majority of that schedule is typically consumed not by final design engineering and construction but rather by the planning and environmental clearance activities. Those efforts are still required even if an alternative project delivery method is utilized for final design and construction. 13.2.1.2 Construction Management-General Constructor (CMGC) This process, sometimes also known as Construction Manager at Risk, typically requires enabling legislation, since the construction team selected isn’t necessarily the low bidder. The owner will first hire an engineering firm to design the project and subsequently provide limited oversight of construction. While the design is underway, but well before it is completed, the owner will pre- qualify construction teams and invite selected teams to respond to a formal request for proposals (RFP). The teams are often composed of a management firm and one or more construction firms. The prequalification and proposal process may be very extensive and includes not only

LRT Track Construction 13-3 preliminary pricing of the in-progress design, but also the qualifications of the candidate CMGC firms and their proposed technical approach to the construction of the project. The owner, usually aided by an engineering firm, will review all proposals submitted and select the CMGC team that they believe will provide the best value. Once the CMGC firm is chosen, they will collaborate with the designer, providing input to the design while they concurrently refine the construction cost estimate. As constructible portions of the design are completed, the CMGC firm negotiates an agreement with the owner as to the final price for that part and then goes to work. This includes both building the job and overseeing the construction activities of subcontractors so as to ensure that it is built to the owner’s and designer’s specifications. The CMGC firm is also tasked with solving problems that may occur on the project. They are generally given very tight schedules to produce the project. Liquidated damages can be high, introducing an element of risk. Once the job is complete, it is then turned over to the owner to operate and maintain. CMGC should be considered when construction contractor input during design is deemed critical and when significant construction-related impacts to the public are expected and a proactive process is needed for their mitigation. An advantage of CMGC is that the owner has the opportunity to develop the RFP with criteria that focus on meeting the objectives for a successful project. This will reduce the risk of awarding the contract to a constructor who lacks the experience and capacity to perform the work. Another advantage is that the owner does not need a large staff to administer the project. This may save the owner both money and liability. A disadvantage is that now the CMGC, in the legitimate pursuit of a profit, might, in the absence of third-party oversight, take shortcuts or overlook deficiencies in the construction. This problem can be minimized if diligent prequalification is performed so that a high-quality project can be achieved. If the selection scoring process is heavily weighted toward getting the lowest first cost, the completed project could possibly have maintenance costs appreciably higher than expected. 13.2.1.3 Design/Build This innovative approach to project procurement has become very popular. Like CMGC, it does not select based solely on a low bid, and enabling legislation is usually required for any public agency to use this method. The owner will generally produce some drawings showing the system in basic format, leaving the details to the design/builder. The drawings are typically taken to a 30%-completion stage although the package may include standard details that are at or near 100%, particularly if the owner is an existing LRT operator. The owner will then issue a request for proposals (RFP) to the contracting community. Teams will form consisting of a designer and a construction contractor. Typically the constructor will be the lead entity. Similar to CMGC, there is generally a prequalification process, and certain teams will be selected as qualified to perform the work. Those consortiums will then be requested to offer pricing on the project. The owner will identify a grading system incorporating components for both price and each team’s technical approach to the design and construction. The scoring system must be identified during the RFP stage. The next step is to receive proposals and begin an evaluation phase to choose the entity with the best score. The evaluation process may take several months to complete before a design/builder is identified.

Track Design Handbook for Light Rail Transit, Second Edition 13-4 As with CMGC, the schedules can be very short since construction can begin before the entire project is designed. This is an advantage but could also be the cause for modifying the work or the design if the pace of construction exceeds the ability of the designer to fully investigate all of the interfaces between facilities and systems. Once the project is built and signed off on, it is then turned over to the owner for testing and operations. Issues concerning the system operator and maintainer are as previously discussed under the traditional approach. The advantage to this procurement method is that the owner will get the system much sooner than the methods discussed above. A significant disadvantage is that unless the 30% design, particularly the design criteria and the specifications, are very specific as to the quality of materials required, the system may be built with materials that meet only the minimum requirements. Since the design/builder will not have any long-term commitment to the system, there is little incentive to provide high-quality products. 13.2.1.4 Design/Build/Operate/Maintain (DBOM) For the owner that simply wants to have a project, but does not want to be involved in day-to-day details of operation and maintenance, the DBOM process is a good method to have a system operational in a very quick manner. The first stages of the project are functionally similar to Design/Build but with the addition of operations and maintenance criteria with which the Concessionaire must comply for some period of time. The concession period could extend for several decades. This DBOM team may also have responsibilities for other aspects of construction such as community relations, mitigation of unforeseen conditions, and public artwork, just to mention a few. These types of responsibilities will add risk that the Concessionaire must anticipate in the bid price and manage during the term of the contract. Because of the risk management issues associated with DBOM, the Concessionaire will very often be a joint venture with a financial services firm as a key partner. Prequalification of DBOM teams is an extremely important part of the project procurement process since failure of the Concessionaire prior to completion of the contract term could have severe impacts. The biggest advantage of the DBOM procurement method is that the Concessionaire has an incentive to use top quality products during construction since it has to maintain what it has built. Accountability is an important part of the process. As with Design/Build, the construction can begin before design is complete. In many cases, testing can commence before construction is complete, and segments of the route may open for revenue service before the entire job is completed. DBOM project procurement can be non-linear, and the implementation schedule can be stacked in many different ways from initiation of design through to the commencement of revenue operations. 13.2.2 Track Material Procurement Procuring trackwork materials in a timely manner for the right price is very important to the project and will set the tone for construction. Many of the materials used in LRT track construction are “long lead items,” and their procurement can range from 6 to 12 months and even more. Delays can occur if the material is not onsite and approved for installation prior to construction. Determining who will purchase the material is an important decision and one that can have large

LRT Track Construction 13-5 ramifications for the success of the project, particularly with respect to the schedule. The two major material procurement options are owner furnished and constructor furnished, and each has advantages and disadvantages. 13.2.2.1 Owner Furnished 13.2.2.1.1 Description of Process If the owner furnishes materials to the constructor, there will be a separate procurement contract or contracts that are prepared and awarded prior to the construction contracts. This overlaps the fabrication time for the materials with the time necessary to complete the design, bidding, and award of the construction contracts. Ideally, this process begins with extremely detailed specifications and drawings. In addition to the normal reviews by the designer’s team and by the owner’s capital projects staff, these documents should be reviewed by the selected maintenance organization since they will ultimately inherit the system. Many problems can be avoided by a simple review process. If this is the first procurement package for a new system, the materials procured may become de facto standards for the owner and any LRT system extensions or renovations may need to be compatible. The next step is to advertise for proposals from track material vendors. Several national industry publications are available for this, and advertisements should not be limited to the local newspaper. However, note that the lead time for some print publications can be lengthy, and cutoff dates may be several weeks in advance of actual publication. Nevertheless, they can be a good way of providing candidate vendors with advance notifications of the bidding and advising them to monitor the owner’s website for detailed information as to when the bid documents are actually available. If allowed under the state regulations under which the owner operates, it may be desirable to pre- qualify vendors on large purchases. A pre-bid meeting may be appropriate but not always necessary. Particularly in the case of complex special trackwork, where the bidder may need to do some additional design work to adapt the project design to standard components, an ample amount of time should be given for bid preparation as well as time allotted for questions. The delivery schedule is an important part of the contract documents and should reflect liquidated damages since the constructor may file a claim if material delivery is delayed past a promised date. Bonds should be required just in case the vendor does not perform, and these bonds should be of a value to cover delays, expected revenue, claims, litigation etc. Bear in mind that the more risk taken on by a contractor, including materials vendors, the higher the bids will be. If there is a possibility of risk sharing, that option should be explored. Naturally, all such bid documents should be closely reviewed by the owner’s legal counsel. In general, any particular type of risk should be borne by the party who is in the best position to manage the risk and implement mitigation measures. Some types of risk can best be managed by the owner while other risk issues are completely outside of the owner’s control. On a complex project with multiple prime contractors, the owner is very often in the best position to manage overall risk. Once the lowest responsive and responsible bidder is identified, the procurement contract can be awarded. Execution of work must closely adhere to the contract requirements. A quality

Track Design Handbook for Light Rail Transit, Second Edition 13-6 management process that includes both quality controls by the vendor and monitoring by the owner and the designer must be followed, including documentation, so that the products furnished to the constructors meet both the specified requirements and the schedule. 13.2.2.1.2 Advantages and Disadvantages to the Owner Advantages of owner furnished to the owner: • On a project that is an extension of an existing LRT system with previously established standards, if the owner furnishes the material to the constructor(s), they can be confident that the new material will be compatible with their existing system. • If it is new construction, material procurement can take place prior to the RFP for construction, compressing the overall schedule. If this method is done properly, the possibility of project delays due to materials being unavailable is greatly minimized. Disadvantages of owner furnished to the owner: • If the owner is not diligent with the procurement and the constructor runs out of material, there will probably be some claims involved for lost time, lost continuity of work, loss of anticipated profit, and extended overhead. • The owner must have the expertise to manage this activity, either with in-house staff or through a construction manager who can act as an extension of staff. The owner or the owner’s designee also must closely monitor the issuance of materials to the constructors and verify that they are not being careless with or wasting the items. Rail can be particularly problematic if the constructor does not carefully plan cuts so as to avoid generating a large pile of unusable short lengths. It is recommended that the bid documents for the construction very specifically itemize by type and quantity any owner- furnished materials that will be issued along with a stipulation that the constructor is responsible for making up any shortfalls. • The owner takes the responsibility and risk of ensuring the quality of material furnished to the constructors. Typically it is necessary to add personnel (either in-house or consultants) to inspect each delivery to ensure conformance with the specifications. • The owner must have secure staging areas to stockpile the material and protect it from damage and theft. 13.2.2.2 Constructor Furnished 13.2.2.2.1 Description of Process The constructor takes the responsibility of furnishing the long lead track materials just as it would handle more routine construction materials. The same sorts of drawings and specifications still need to be developed; however, the risk is now in the hands of the constructor and its suppliers. If the owner decides to intervene for any reason at this phase, costs will likely escalate and claims will likely ensue from both the constructor and its supplier.

LRT Track Construction 13-7 The owner must have a process in place to review and approve shop drawings prior to the constructor purchasing the material. Bear in mind that if any changes are identified during those shop drawing reviews, they may result in a claim or change order that in most cases will add cost to the project. In design/build projects, the owner may not have any direct control over the shop drawing process. Nevertheless, the owner will virtually always maintain the right to review the contractor’s design for its compliance with the performance specification that was the basis for the design/builder’s proposal. The owner will want to be certain that all materials conform to not only the specification, but also the quality program that the constructor would have submitted, either with the bid package or shortly after award of contract. 13.2.2.2.2 Advantages and Disadvantages to the Owner Advantages of constructor furnished to the owner: • The constructor now accepts the risk of inadequate or defective material and can be held accountable. • The constructor is responsible for interface compatibility and for quantities. • The owner may get better pricing since the constructor can cover some risk in the procurement of material and may have better buying potential. • The owner will not need as many field personnel or as much equipment during the receiving stage. • The constructor now accepts the risk of transportation of the material from the supplier, including unloading in its own staging areas. The owner does not have the responsibility to protect the material from damage or theft. Disadvantages of constructor furnished to the owner: • The construction schedule must now include time for procurement of long lead items. In a traditional Design/Bid/Build project procurement process, this can be a distinct problem. It is generally not a problem under alternative project procurement methods such as Design/Build and DBOM. • If the owner is an existing transit system with an established inventory of spare parts, procurement of the materials through the constructor increases the probability of getting materials incompatible with the existing system since one level of controls has been eliminated. This could dramatically affect both the Maintainer’s required spare parts inventory and the service life of the system. 13.2.3 Design Concept Both the clarity of the design and the constructability of the design are absolutely crucial to the success of any project. The intent of this article is to address those topics, offer some thoughts concerning pros and cons of various design concepts and offer counsel concerning the degree of

Track Design Handbook for Light Rail Transit, Second Edition 13-8 construction difficulty. Some designs are easy to build, some are hard to build, and some are impossible to build. Finding the right mix is the challenge in producing a safe and reliable system. 13.2.3.1 Clarity of Drawings and Specifications Under the conventional Design/Bid/Build project procurement method, the clarity of the 100% bid- ready design documents is imperative. Prior to advertisement they must be scrutinized to make certain that there are no ambiguities concerning the designer’s intent on critical items that might invalidate assumptions concerning the operation and maintenance of the system. It is the nature of all construction to build projects at the least cost and the highest possible profit to the constructor. If there are flaws or irregularities in the bid documents that must be corrected after contract award so that the owner gets the project it wants, claims, change orders, and possibly even litigation will ensue. Trackwork is deceptively simple in appearance but very complex in its details. The design engineer preparing the drawings and writing the specifications should be qualified and very familiar with the entire process from inception to completion. Many rail transit projects have stumbled because the trackwork design was assigned to a junior-level civil engineer with inadequate supervision and oversight. Particularly under those circumstances, using a second, third, or fourth pair of eyes to review bid documents before they are advertised can save millions of dollars in the overall project as well as embarrassment to the designer and the owner. Extreme care must be taken when using design criteria, drawing details, and specifications from other, and nominally similar projects. In many cases, there are appreciable differences in the functional requirements of the projects. The borrowed information may also be outdated. The rail industry is constantly evolving, and new processes and better materials are frequently available. On the other hand, new products are often developed by suppliers who themselves are new to the industry and therefore don’t understand the service requirements that are imposed on railway infrastructure. Therefore, careful research and testing are imperative. 13.2.3.2 Keeping the Maintainers in Mind When designing and constructing a rail transit system, it is highly advisable to include the people that will be maintaining the system in any decision-making process. This is especially important on any mature system that already has a maintenance organization. Asking for their advice or review of documents will help avoid compatibility problems as well as facilitate the development of a unified team that will help the project succeed. In the case of a starter system, the Maintainers are often not identified until the construction is well underway, by which time there is little flexibility for design detail changes. In those cases, it may be prudent to include some personnel with rail transit maintenance expertise during the design reviews. Their expertise can often make the difference between a successful project and one that needs extensive maintenance and possibly even reconstruction in only a few years. 13.2.3.3 Traction Power Stray Current Corrosion due to stray traction power current can be devastating to a track system and has caused failures and premature degradation on many transit systems. The decisions made at the beginning of the project with respect to control of stray current will dictate the success or failure for decades to come. There are numerous examples of the damage stray current can do to the system and how it can affect the safety of persons riding and maintaining the system. While

LRT Track Construction 13-9 Chapter 8 covers this topic more extensively, the discussion below addresses stray current from a construction perspective. In a typical electrified rail transit system, the traction power current leaves the substation using either an overhead catenary system or a power rail (also known as “contact rail” or “third rail”). In general, these systems are DC (direct current) at a potential of 600 to 750 volts. The current then passes through the propulsion control system and the traction motors. The return path from the motors to the substation is through the vehicle trucks and wheels to the running rails. The rails carry the current back to the negative bus in the substation. There is no such thing as a perfect conductor that offers zero resistance to electric current, and the rails are no exception. Because of this resistance, a portion of the current will leak off the rail and seek other paths back to the traction power substation. This is known as “stray current.” The stray current seeks other grounded structures and follows those paths on a zig-zag path back to the substation. Wherever this current leaves one metallic conductor (such as the rail) and jumps to another conductor (such as a water line) corrosion is initiated on whichever conductor the current is leaving. Ideally, the rails are sufficiently insulated that only trace amounts of stray current leak from them. However, there are no perfect insulators, particularly in the gritty environment typical of railway tracks. So, additional measures are usually necessary to protect surrounding structures, particularly any steel reinforcement in concrete structures supporting the trackway. As is described in more detail in Chapter 8, one method is to electrically bond all of the reinforcing steel together so that there is no difference in electrical potential between them. The other is to use epoxy-coated reinforcing steel so that current flow from one bar to another is prevented. Regardless of the steps taken to control stray currents, it is highly recommend that a baseline survey of existing stray current be performed prior to any construction activities. Stray current can originate from many sources that have nothing to do with the rail transit line. Identifying the sources and intensities of any such background stray current is essential to understanding whether the rail isolation measures taken are effective. This information will help prevent disputes as well as protect the new system from damage due to outside sources. 13.2.3.3.1 Stray Current Isolation The method of isolating the running rail will differ depending on whether the trackform is “open,” with the rails fully exposed, or “closed,” with only the running surface on the top of the rail head visible. Open trackforms, which include ballasted track and direct fixation track, are generally much easier to isolate since the electrical isolation can be confined to the rail fastening system. Closed trackforms, which include embedded track, grass track, and railway/highway at-grade crossings, are far more difficult to insulate and keep insulated. This is because not only does most of the surface of the rail need to be encapsulated, the isolation system needs to be able to survive and function within a generally dirty environment, particularly when in a public street. Further, in the case of embedded track and grade crossings, the insulated track needs to function under not only the loadings imposed by rail vehicles, but also the wheel loads of rubber-tired traffic, including heavy trucks. In addition, electrical isolation systems for closed trackforms are often abused by a wide variety of chemicals, particularly in cold climate zones where de-icing products are used to keep the streets clear.

Track Design Handbook for Light Rail Transit, Second Edition 13-10 Products that can be used for electrically isolating the track are discussed in Chapters 5 and 8, and that information will not be repeated here. Note that the electrical isolation system should not prevent the rail from deflecting under load. The rail should be able to vertically deflect about ⅛ to ¼ inch [3 to 6 mm]; otherwise, the system will very likely radiate noise and vibrations and corrugations will develop on the top surface of the rail. This resiliency is very important in embedded track because the vibration from stiff track can degrade the surrounding concrete in a short amount of time. See Chapters 4 and 9 for additional discussion of track stiffness. Regardless of the trackform or the method of electrical isolation, the most important factor for success versus failure is the quality processes that are used during isolation material manufacturing and its installation during construction. Unless a comprehensive quality program is developed and properly executed, the electrical isolation systems will fail, stray currents will ensue, and damages will occur. Failed electrical isolation systems have resulted in major corrosion damage to underground utility lines. There have even been serious injuries to personnel due to leakage of the return current. The cost of correcting these damages can be huge compared to the cost of having done it right the first time. Locations of stray current leakage can be nearly imperceptible under visual inspection. One pin- sized hole in any encapsulation method can cause a “hot spot” of leakage, and corrosion of the rail steel will commence. Once the current begins traveling along reinforcing steel, utilities, and other buried structures, the problem is compounded by additional corrosion each time the current leaves one unintended conductor and leaps to another. 13.2.3.3.2 Stray Current Collection Building track that is electrically isolated can be easy compared to the task of maintaining those insulation systems. Both embedded track and open trackforms in tunnels often require continuous maintenance attention to keep them clean so that stray currents don’t simply bypass the insulation systems. Even with diligent housekeeping, which few publicly funded transit systems can afford, some trace amounts of stray current are inevitable. Because of this inevitable leakage, some transit systems incorporate measures to safely collect it and carry it back to the substations. This requires that all surrounding steel, including reinforcing steel, be electrically bonded together into a continuous grid. Epoxy-coated reinforcing steel is typically not used in this case. This grid of steel is now connected to a grounding cable leading back to the substation. Extreme care must be taken since any discontinuities will create “hot spots” that could allow uncontrolled stray current leakage and even risk life-threatening injuries to personnel. Stray current collection is therefore generally used only as a last resort back-up to stray current isolation. See Chapter 8 for additional discussion on stray current and corrosion control. 13.2.3.3.3 Inspection of Electrical Isolation Construction The importance of inspecting those measures taken to ensure that traction power return current does not leak from the track cannot be overstated. Particularly in embedded track, it is all too easy for a fault in the insulation system to be concealed by later construction. This includes damage that is caused by the subsequent work. The electrical isolation measures therefore must be inspected during each stage of construction so as provide assurance that they are functional.

LRT Track Construction 13-11 If electrical isolation is only checked at the end of the construction, any requisite repairs will be far more expensive than if the issue was discovered earlier. 13.2.3.4 Tolerances Realistic tolerances for manufacturing and construction must be identified in the bid documents and coordinated with each other so that the track system can meet the expected performance requirements. Manufacturing tolerances for track materials are typically well defined in industry documents such as the AREMA Manual for Railway Engineering and their Portfolio of Trackwork Plans. The typical construction tolerances for LRT track construction have been ⅛ inch [3 mm] on everything, including gauge, line, and surface. These tolerances, which are driven by ride quality issues, are much more restrictive than most railroad track construction contractors are used to dealing with, and it is important that they are clearly defined and enforced. Some designers include even tighter tolerances in the bid documents, often rationalizing that by specifying an extremely tight dimension, there’s a better chance that the constructor will achieve some looser figure that is the designer’s real goal. This practice is not in the best interest of the owner. Establishing construction tolerances that are not readily achievable, such 1/16 to 1/32 inch [1 to 0.5 mm] on gauge or alignment, will only cause increased cost without actually improving quality. The materials being used include fabrication tolerances, and the accumulation of allowable fabrication tolerances within subassemblies plus their assembly can make ultra-tight construction tolerances virtually impossible to achieve. The bidders will protect themselves against the possibility that the owner might actually expect these ultra-tight tolerances by including a contingency in their bid prices. That way, if the owner agrees to waive a particular tolerance in return for a price credit, the constructor will not actually lose any money. Other constructors may elect to not bid the project rather than deal with the risk and aggravations involved in unreasonably tight tolerances. Specifying rational construction tolerances that can meet the actual quality requirements and be achieved with commonly available materials is in the best interest of all parties. It is important to understand that construction tolerances have absolutely nothing to do with either maintenance limits or safety tolerances. Those factors are relevant only to the Maintainers of the system, not the constructors. The limits called out in the FRA and APTA Track Safety Standards indicate conditions at which either corrective repairs are required or train speeds must be reduced. They have no relationship to construction tolerances and cannot be used as a justification for not meeting the tolerances specified for newly constructed track. 13.2.3.5 Special Trackwork Details of special trackwork components are discussed in Chapter 6. The discussion here relates to issues the designer needs to understand about how special trackwork is fabricated and installed. As with all trackwork, the needs and issues of the Maintainer should be kept in mind during design. Simplification of the spare parts inventory is a high priority for any maintenance staff and is extremely important when it comes to special trackwork. Having different styles, shapes, and sizes of special trackwork can make maintenance activities much more complex and difficult than necessary. Non-interchangeable parts increase the risk that the Maintainers will undertake

Track Design Handbook for Light Rail Transit, Second Edition 13-12 emergency field modifications that could unintentionally jeopardize both the integrity of the track and the safety of the passengers. 13.2.3.5.1 Special Trackwork Fabrication Inspection Inspecting material and processes during all phases of the project is important. It is therefore strongly recommended that special trackwork be fully assembled in the fabricator’s shop for the final inspection. If the first time the whole layout is assembled isn’t until after it arrives at the job site, it can be virtually guaranteed that some component will not fit within specified tolerances. So as to eliminate any future claims by the constructor that the special trackwork is defective, the constructor should be required to participate in the shop inspection even if the procurement and installation of the special trackwork are in separate contracts. This co-inspection also gives the constructor the opportunity to coordinate with the fabricator on issues related to packaging and shipping the special trackwork so as to facilitate the constructor’s requirements. The owner’s requirements for plant inspection of special trackwork should be clearly spelled out in the bid documents. Typically, the special trackwork is fabricated far away from the actual project site, and travel costs and logistics preclude casual inspection visits. It is therefore important that the material actually be ready for inspection on the stipulated date. The contract should stipulate that the manufacturer’s own quality processes will have identified and corrected any deficiencies prior to the arrival of the owner’s inspector and that the inspector be given sufficient time to perform thorough inspections without interference from other plant activities. Ensure that the manufacturer is following a quality assurance plan specific to its means and methods as well as the requirements of the contract. If the manufacturer is ISO 9000 compliant, all records should be submitted for compliance. Sharing, cataloging, and controlling documents should be the norm. Requirements for storage of record documents should be established by the contract. 13.2.3.5.2 Shipping, Handling, and Installation Basic requirements for packaging and shipping should be identified in the contract, and the actual handling methods proposed to be used should be submitted for acceptance. The method to be used for unloading trucks is important so that the manufacturer loads the trucks accordingly. Few jobsites are equipped with loading docks, and therefore must be unloaded from the side rather than the end. Packaging also must be suited for the particular equipment used to unload trucks. These types of practices should be identified and resolved before any shipment of material. This will reduce, if not eliminate, possible damage due to poor unloading practices. It is advised that all equipment be identified for the safe unloading of material. The manufacturer’s handling instructions should identify recommended equipment and methods for unloading and installing the material. The constructor’s quality group should follow up to verify that the procedures are being followed. 13.2.4 Preparatory Work This article should be considered as a checklist for the designer. The objective is to highlight to the designer some stumbling block topics that may arise during the course of construction with the goal of identifying constructability issues at an early date when it is still possible to resolve

LRT Track Construction 13-13 them at lower cost. If such matters are not discovered until the construction phase, it typically results in delays, design changes, change orders, claims, counterclaims, and possibly even litigation. 13.2.4.1 Site Plan It is recommended that the designer develop an overall site plan of the project, including staging areas, material stock pile locations, and access opportunities and limitations. The site plan should identify access points, construction roads, and an overall flow of trucks for the delivery of material. Locations for office trailers and fuel storage should also be identified. This will enable the design team to more accurately understand how the project will be built and how much it will cost to do so. This site plan can be included in the bid documents as a “For Information Only” sheet so that bidders understand and can benefit from the designer’s perspective on the project’s construction. Further development, submission, and approval of the final site plan by the constructor(s) should be a contract requirement before site mobilization begins. The constructor’s version will be much more detailed and will show access points, staging areas, and flow of construction equipment. Staging areas should be shown, and areas identified for stockpiling of each type of material. This plan should show the entrance points for material deliveries and exit points for all vehicles. Some material is delivered by tractor and trailer, some is delivered by rail, and some by small box-type trucks. A well conceived site plan will help the constructor, designer, owner, and any third-party stakeholders (such as the community) reach a common understanding of the construction process and achieve a goal of “no surprises.” 13.2.4.2 Accessibility Access to the work site has a major effect on the smooth progression of any construction project and can make a big difference in the cost of construction as well as the schedule. Access points and staging areas need to be strategically located for continuity of work. This is particularly important on a linear and sequential project such as building track. For example, if on a ballasted track project, ballast can only be stockpiled at one end of the job, there could be disruption to other construction activities so as to allow ballast trains to pass through. There are also risks associated with double handling of ballast and its contamination, degradation, and segregation before it can be placed in the track. 13.2.4.3 Continuity of the Work Any time an activity comes to a halt and must start again, two things happen: • The follow-on activities also come to a halt and “stack up,” which means that in order to establish continuity again, each one must start fresh and advance far enough to allow each of the other activities to begin. • Another learning curve takes place, and this is where cost versus productivity is impacted. In some cases, the constructor may have moved on to other areas or even other projects and when the time comes to begin again, there may be new personnel involved, which causes low production and can affect quality if proper quality control measures are not implemented.

Track Design Handbook for Light Rail Transit, Second Edition 13-14 13.2.4.4 Vehicular Traffic Management Especially if a project is in an urban environment, vehicular traffic must be taken into consideration. Detours should be identified and permits requested well in advance of construction. In embedded track areas, streets may need to be closed for track construction and intersections closed or rerouted. Sometimes it is necessary to close street blocks without also closing the adjacent intersections. This can add cost to the project as any discontinuity of constructing the track will add cost due to remobilization. Longer work zones can be constructed at less cost per unit length than short stretches. 13.2.4.5 Pedestrian Traffic Management When designing and constructing track in an urban environment, the walking public must be taken into consideration also. The construction may block foot paths or sidewalks. These pedestrian walkways must be properly rerouted so people do not walk through the construction site and get injured. Pedestrian traffic must be identified and managed during both construction hours and off hours. Understanding that a constructor will need to cut rail and make field welds will help identify clearance zones. Pedestrian bridges that are only a short distance above the pavement can still allow a constructor to have continuity of track construction while maintaining pedestrian flow. Nevertheless, it is advisable to completely separate the construction from the general public whenever at all possible. 13.2.4.6 Pre-Inspection This activity is a must and may—by identifying interferences and other issues early, when they can be mitigated—prevent them from becoming costly delays during construction. The right-of- way as well as the surrounding community should be inspected by as many disciplines as possible with the object of spotting potential problems with design, construction, and maintenance. This activity could prevent millions of dollars of additional cost and delays by identifying the interferences as well as the associated risks. This will allow for a risk analysis to be performed on the problems and mitigation resolved. This can be as simple as finding a fire hydrant that was not recognized on the drawings or a manhole that is located in the centerline of the track. 13.2.4.7 Baseline Stray Current Report Stray current is a very serious problem with electrified transit systems. It has nearly destroyed track and severely impacted many transit systems in the United States. There are books written on the subject as well as many lessons learned. The designers should familiarize themselves with as much information as possible prior to making decisions that could affect the longevity of the system. It is a good practice to do a baseline survey of existing stray currents that may be in the ground before any construction begins. This information would offer the utility company(s) time to correct any problems and possibly install cathodic protection on the existing utilities. This survey could be a very important document that could possibly protect the owner and the project from future litigation. See Chapter 8 of this Handbook for additional information on stray current. 13.2.4.8 Contaminated and Hazardous Materials When excavating for certain trackforms, it is best to understand what is in the ground prior to excavating for embedded track. In urban areas, it is virtually certain that contaminated and hazardous materials will be encountered during excavation, and an action plan should be

LRT Track Construction 13-15 prepared so that there is no lost time in production and claim negotiation. These types of materials may fall into the category of “unforeseen” conditions and may stop a job in its tracks. In some cases, it may be prudent to establish a fund of money to cover these conditions and allow the constructor to draw from this fund on a time and material basis. Archeological finds are possible and can also delay a project. A review of the project’s environmental clearance documentation will sometimes provide information about where hazardous materials and archeological items might be found. Such information generally should be included in the construction contract documents “for information only.” This enables the constructors to have an action plan in place for such situations, thereby minimizing claims and delays. 13.2.4.9 Permitting A wide array of permits and permissions are required from public agencies before construction can proceed. Clearances are also often required from public utilities and railroads whose facilities are affected by the project. The permits required should be identified well in advance, including who is responsible for getting them. It may take a very long time to get certain permits and to simply assign the obligation to the constructor may delay a project. The designing engineer will at least have the responsibility to verify and identify all permits that are required or may be required. In general, permits that relate to the details of the design should be secured by the owner or designer. Permits that relate to the constructor’s means and methods and how those processes affect the community should be obtained by the constructor. In many cases, the design team will have laid the groundwork for those constructor permits. 13.2.4.9.1 Detours When the project is constructed within a city street, setting up detours and maintaining vehicular traffic can be a full-time job for a significant part of the constructor’s team. Synchronizing roadway outages with the construction schedule is always a challenge. Confirming that all the material and equipment needed for a construction activity is actually at the site prior to closing roadways is essential. It may not be advisable to close roadways when certain material is only promised to be on site in time. Permits and advance warning notifications should be the norm. Understanding the municipality’s requirements is important also. Some may have a moratorium on cutting fresh asphalt or may not allow detours during certain sporting events or concerts. Some owners may have a restriction on activities performed between Thanksgiving and Christmas, during the shopping season. Pedestrian traffic must be maintained as well, including access to and space for existing bus stops. These matters should be investigated early, and the accepted mitigation measures clearly identified in the bid documents. That way, the constructor will have budget in the bid prices to address these matters and can structure a work plan to accommodate the requirements. The alternative—identification of needs only as they arise—will only result in delays, claims from the constructor, a dissatisfied public, and an owner who is upset with the designer. 13.2.4.9.2 Fire/Emergency Response Notifying emergency responders is always advisable in order to have a smooth running project. Firehouses and Police departments must know which roads will be closed and how construction will impact their normal activities.

Track Design Handbook for Light Rail Transit, Second Edition 13-16 13.2.4.9.3 Dig Safe The appropriate utility companies should always be notified prior to any excavation. Generally, on any LRT project, there has been extensive coordination with the utilities during the design phase of the project; therefore, most, if not all, of the utilities will have been relocated well in advance of track construction. Nonetheless, this must always be verified. The contract documents must be very specific about who is responsible for the notification to utilities and whether allowances must be made in the project schedule for utility work. It is particularly important to identify any situations where the constructor must work around live utility lines that are to remain in place. Such situations may have a direct effect on the constructor’s means and methods and, hence, costs. Leaving these issues up to the constructor can delay projects and incur extra work claims, especially if there are utility interferences. If such interferences exist, time must be reallocated in the schedule to allow for relocating the utilities so that they are not in conflict with the system construction. 13.2.4.10 Scheduling/Planning This single activity can be the downfall of any project if not performed properly. The persons involved should be professionals at making schedules and planning activities. There should be a detailed understanding of how long it takes to perform activities and which ones will impact the follow-on activities. This analysis ultimately defines the project’s “critical path” and is documented in a baseline Critical Path Management (CPM) schedule. Many disciplines should be involved in the creation of this document. This document will identify potential delays and offer opportunities to recover from them. The constructor and the engineer are the drivers behind the CPM. This document should be produced well in advance of construction and periodically adjusted and updated to reflect progress. This document will also serve as a tool for evaluation of claims and change orders. It is strongly recommended that construction should not begin unless everyone involved agrees that the baseline CPM represents the path on which the job will progress. 13.2.4.10.1 Risk Analysis Beginning a project without performing a detailed risk analysis can be deadly. This risk analysis is simply playing the “what-if” game. There have been volumes written about risk analysis, and many methods can be employed, but the basic concept is simple. The engineer, constructor, or owner will take a certain activity and develop all the things that could go wrong, the probability of that occurring, and have an action plan for each one. If the outcome is too severe, a mitigation process takes place to reduce the risk, such as by doing it another way. An example may be an activity that could cause serious injury or loss of life. The easy mitigation is to take the human out of the equation. The designer should be knowledgeable about the activities that will put too much risk onto the project and identify strategies to reduce that risk to an acceptable level. 13.2.4.10.2 Survey A topographic and land survey must be performed to support the final design. Under the Design/Build project procurement method, it is sometimes possible for the owner to limit the pre- contract survey to simply identifying the right-of-way and offering design criteria for the constructor to work out the civil engineering details. A word of caution: if the project right-of-way is a former railroad corridor, the real property boundaries shown on the railroad company’s “valuation maps” could be grossly out of date. In any event, the right-of-way must be established and clearly marked, including benchmarks and monuments for reference during construction.

LRT Track Construction 13-17 This survey may be very elaborate if the documents are brought to the 100% stage. This survey also forms the basis for interferences with utilities or structures. 13.2.4.10.3 Document Control Document control can be an entire division within a company that has the sole purpose of making sure that all paper is stored and cataloged properly. Security is a very important part of document control. In some cases, redundancy, such as off-site storage of back-up copies, will be employed to address issues such as loss due to disasters such as fires or floods. Electronic storage is a challenge including proper back-up and security. Going paperless is good for the environment, but it must be remembered that security for electronic files can be overwhelming, especially if there is litigation at the end of the project. All electronic material must have very special measures employed so that no one can tamper with these documents. The FRA has identified some methods, but at this writing still requires paper for audits. Organization is the key to good document control. 13.2.4.11 On-Track Construction Equipment Typically, the constructor will need hundreds of items of construction equipment to build the job and some of that will need to be able to ride on the rails. However, even if the track on the project is standard gauge, on-track equipment that is designed to work on a freight railroad will not necessarily fit the trackwork and clearances of a light rail transit project. See Chapter 14, Article 14.6.1 for additional guidance on this matter. Whatever limitations the track or guideway might place on the constructor’s equipment should be clearly identified in the contract bid documents. 13.2.5 Relocation of Utilities Identifying potential interferences with local utilities prior to construction activities is imperative. The level of utility investigation usually performed for a civil/highway project may provide insufficient detail for an LRT construction project. There are a host of utilities that could be affected by the construction or must be protected during construction. Protection slabs and corrosion control measures may be necessary. Utility companies should be notified early in the design process and continuously kept abreast of the project progress. Pre-meetings (both pre- design and pre-construction) are a great resource, and utility companies appreciate being invited and made part of the process. 13.2.6 Activate Detours Coordination with the highway department(s) and emergency response organizations is imperative, and the designer should notify these agencies and ask for input on disruption to their system so that appropriate requirements are included in the project procurement documents. Note that some projects will cross multiple jurisdictions, and the requirements of each might well vary. 13.2.7 Quality Process Maintenance of an acceptable level of quality in the construction is arguably the most important activity for a successful project. Projects and project subcomponents will fail, or at best, struggle

Track Design Handbook for Light Rail Transit, Second Edition 13-18 forever without a good quality program (QP) during construction. Quality includes both quality control and quality assurance. 13.2.7.1 Developing the Quality Program The constructor should be in direct control of the quality of construction. The work should include the first level of inspection, testing, and verification that a feature is constructed with material and workmanship that meet the requirements of the contract. The quality control program should consist of the plans, procedures, and organization necessary to provide inspection, testing, and verification that materials, equipment, workmanship, fabrication, construction, and operations comply with contract requirements. The constructor’s quality control plan (QCP) should be submitted, reviewed, and accepted prior to any commencement of work or production of material. This plan should include at a minimum: • A description of the QCP management organization. This should include an organization chart showing the relationship of the quality control organization to other elements of the constructor’s project staff and overall organization. • Number, classification, qualifications, duties, responsibilities, and authority of personnel. • Procedures for processing contract submittals. • Inspection, testing, and verification activities to be performed to ensure compliance with contract requirements, including such activities performed by subcontractors, suppliers, and off-site fabricators as a part of the requisite quality control system of each subcontractor, supplier, and off-site fabricator to ensure compliance with the requirements of the QCP. • Testing procedures, including recording and reporting test results. • Format for documentation of the QCP activities. • A copy of the letter appointing the QCP manager, signed by an officer of the firm, outlining the QCP manager’s duties, responsibilities, and authority. Categories of a good plan should at a minimum include the following: A. General a. Definitions b. Responsibilities c. Constructor and engineer d. Coordination meeting B. Quality control plan a. General b. Organization, staffing, and hierarchies of responsibility and authority c. Staff C. Testing and testing plan D. Control of measuring and testing equipment E. Completion inspection F. Documentation a. Preparatory phase checklists b. Checklist prior to placement of plinth concrete

LRT Track Construction 13-19 c. Plinth concrete placement d. Plinth concrete post placement e. General trackwork f. Skeletonized track g. Track type h. Welded rail G. Quality program sign-off H. Elements of control I. Management of submittals J. Material handling K. Subcontractor and supplier control L. Control of construction M. Control of nonconforming conditions N. Audits and procedures for audits 13.2.7.2 Checklists Checklists are a valuable document to maintain and make part of the document control system. These are simple reminders of what to look for prior to a phase of construction proceeding. These checklists should be filled out and signed by a qualified person and acknowledged by a supervisor. In some plans, these checklists become “stopping points” if deficiencies are identified. If the deficiencies are not corrected, they could become a non-conformance item that must be corrected prior to acceptance. Checklists should be project-specific since projects vary, with widely different standards and requirements for design, materials, methodologies, and workmanship. 13.2.7.3 Non-Conformance Reports During construction it is common for the inspector to write non-conformance reports (NCRs) that simply mean that the constructor is deficient with some aspect of the project. Generally, this means that the constructor has violated a specific aspect of the specifications. The NCR must be satisfied prior to acceptance of the project. It is good practice to immediately fix the problem and have the author of the non-conformance violation sign-off that it was completed satisfactorily. An NCR is a serious violation and should not be confused with punchlist items. An NCR will only be written if there is a complete disregard of the performance standards. An example of an NCR would be that the constructor used material that did not comply with the specifications, such as inferior concrete ties or direct fixation fasteners. An example of a punchlist item would be that the strands in the concrete tie protruded more than the criteria. In general, NCRs are non-negotiable whereas a punchlist item may be waived due to negotiating tactics. An NCR would be something that jeopardizes the safety of the system whereas a punchlist item would be a minor infraction. An analogy might be speeding in a school zone as opposed to speeding on a rural Interstate highway. 13.2.8 Reinforcing Steel (Embedded and Direct Fixation Track) Because of the possibility of stray traction power current, extraordinary measures must be taken with the reinforcing steel used in rail transit concrete structures. The paragraphs below elaborate on those issues.

Track Design Handbook for Light Rail Transit, Second Edition 13-20 13.2.8.1 Epoxy-Coated Rebar If the method of controlling stray current is the “isolation” method, it is necessary to coat the reinforcing steel with epoxy. This adds another level of protection from stray current. Welding epoxy-coated rebar together is not required. When using epoxy-coated rebar it must be understood that if the epoxy is chipped or compromised, it must be repaired with an approved coating. If epoxy-coated rebar is cut for any reason, the exposed end must be painted with epoxy. If the bars are scratched or nicked in any way, they must be touched up with epoxy paint. Detecting and correcting all such issues before the concrete is poured is a major job in itself. Continuous inspection is usually necessary as the bars are placed as subsequent bar placement may make visual inspection and correction difficult to impossible. Quality programs must address this prior to any concrete being placed. 13.2.8.2 Black (Uncoated) Rebar Uncoated reinforcing steel should be welded together to ensure a continuous mat, cage, or grid. This is commonly called electrical bonding. If there is one piece of rebar that did not get properly attached to the grid, that piece will become a “hot spot” where stray current will migrate and begin the deterioration of the entire concrete slab or nearby utilities. The entire reinforcing steel system is electrically bonded and connected back to the negative side of the traction power system. As when using epoxy-coated rebar, this method requires intense quality control measures to detect and correct locations where intersecting bars have not been properly bonded. Factory-made welded bar mats can dramatically reduce the amount of field labor and associated costs. 13.2.8.3 Quality, Risk, and Cost Whichever method is chosen, it is imperative that good quality control systems are in place. Using uncoated steel is somewhat more risky than using epoxy-coated steel. When a risk analysis is performed, it should be apparent that isolating the rail with as many redundancies as practical is a better method. Cost is a factor; therefore, it may be wise to do a cost analysis along with the risk analysis. If the rail is fully isolated, there will be little to no stray current and no appreciable opportunities for failure. 13.2.9 Rail Grinding Rail grinding is frequently the last major construction activity undertaken by the track constructor. This topic is discussed extensively in other Chapters of the Handbook and will not be repeated here. See the following Articles for additional information: • Chapter 4, Article 4.2.5.3 • Chapter 9, Article 9.2.1 • Chapter 14, Articles 14.6.2.2 and 14.6.3.8 13.2.10 Track Geometry Verification Before final acceptance, it is usually required to verify that the track, as constructed, meets all the geometric requirements of the contract. This includes the verification of gauge and superelevation as well as the actual as-built location of the track. Often times, it is proposed to use a “track geometry car” to collect this information. Geometry cars can be a very useful tool for

LRT Track Construction 13-21 collecting some of this information, but the raw output data are generally not immediately useful without some analysis. Track geometry cars are generally programmed to detect deviations from a particular FRA track class and the raw output data need to be filtered to gain an accurate understanding of the actual conditions. Plus, the geometry car cannot verify that the actual as- built location of the track is within tolerances of the mathematized alignment shown on the plan and profile drawings. Hence, it is typically necessary to supplement the geometry car data with information collected by traditional manual topographic surveying methods. 13.2.11 Project Close-Out This activity can take a long time, and this discussion will offer the designer some tips on how to expedite the completion of a project. The project close-out process should actually begin at the very beginning of the project and continue until completed. The methods and procedures for close- out should be as detailed as the construction itself. It can be detrimental to a project that waits until the end to close-out. Usually, the key people will have moved on to the next project, and valuable information is lost or forgotten. In some cases, this activity may take as long as the construction did; therefore, some activities should be continuous and closed out as they come to an end. 13.2.11.1 Clean-Up Cleaning up the project can be a very cumbersome and overwhelming process. This not only pertains to the physical cleanliness of the structure but also to the organizational aspect of the quality programs. If they are attended to as the work progresses, the end is not so overwhelming. If everything is left to the end, it can be so overwhelming that corners may be cut and details overlooked. This could lead to an owner that is not pleased with the project or that has some concerns with the safety and reliability of the system. In some cases, the clean-up is pushed by politics, and quality is what suffers. The clean-up should also begin with the construction, and, if all is done properly, the close-out is simply a handoff. Checklists can also be used for this activity. A brief example would be as follows: • Material certifications • Final quantities for unit price items • Verification that all subparts of lump sum items are complete • Resolution of change orders and claims • As-built drawings • Resolution of final contract amount • Resolution of time-related issues • Timetable for close-out set • Close-out subcontracts • Final EEO report • Special warrantees, insurance, or extended warrantees • Final quality control documentation is transmitted • Final invoice with retention payment prepared and submitted • All equipment and small tools returned • Temporary utilities disconnected • Temporary facilities removed • Final jobsite clean-up • Site demobilized

Track Design Handbook for Light Rail Transit, Second Edition 13-22 13.2.11.2 Safety Certification Safety certification, which is now an FTA requirement, is a process that begins during final design engineering and extends through the construction process. A safety certification process, managed by safety specialists, will result in certification checklists that must be completed at milestones in the design and construction process. This affects all elements of the constructed project, including trackwork. The constructor should obtain a safety certification checklist from the owner prior to beginning work. As construction progresses, the necessary inspection records needed to satisfy the certification can be collected and the items on the checklist completed. 13.2.11.3 Documentation Retention/Storage Choosing the right way to store all the documents that are produced during the course of a project is paramount to the success of the project. Back-up systems, security systems, access systems, and a cataloging system must be chosen, and, once a system of document control becomes active, it is difficult to change during the course of the project. Many agencies are going “paperless,” and this presents some challenges. E-mails present special challenges and their storage is very important. Directives that result in major changes in a project, potentially costing someone millions of dollars, have been given through an e-mail. Having a system that cannot be altered at a later date is a must, especially in the event that there is litigation at the end of the job. When choosing a system for proper storage of documents, it may be wise to use a consultant that is well versed in the subject and can suggest ways to protect against the types of document fraud that could take place. If paper systems are chosen, they also must have certain safeguards in place. Scanning paper into electronic form is a good back-up. Information management technology is constantly evolving, and research to find the best system for a particular project is necessary to ensure that all documentation is accurate and accounted for. 13.2.11.4 Project Record Documents (“As-Built” Drawings) The project record documents include not only updated versions of the original contract drawings but also drawings, shop drawings, photographs, field sketches, revised specifications, correspondence, and any other information that provides a complete and accurate record of the project’s end product. At the end of the project, these documents must be submitted to the owner. All approved change orders or other design modifications, punchlist signoffs, and non- conformance report resolutions should be included in this final document. Submittal and acceptance of the project record documents should be linked to final payment. This activity should actually begin at the beginning of construction and continue until all trackwork is built and accepted. If accurate records are kept in an organized fashion during construction, completion of project record documents can be a relatively simple task. If not, much of the needed data may be difficult or impossible to resurrect, and final payment to the constructor could be jeopardized. It may be very difficult to resurrect information after the track or track components are embedded in concrete or otherwise concealed; therefore, every change of field conditions or change to the bid documents must be recorded as they occur and not after the fact. It’s also necessary to keep up with the paper documentation trail. For instance, mill certifications for furnished materials are typically required by the specifications, and missing certifications are

LRT Track Construction 13-23 cause for a non-conformance report (NCR). In general, all NCRs must be signed off on before final payment or retention is released. Waiting until the end of the project to ask suppliers for mill certifications and then waiting for the suppliers to come up with them would therefore affect final payment. Since the suppliers may have long since been paid for their products and services, they may have little incentive to follow through with deferred paperwork. 13.2.11.5 NCR Sign-Off An NCR is a formal document that is produced during the course of construction. An NCR is not just for physical construction non-conformance, it can be related to specifications or shop drawings. Anything at all that does not conform to the original documents should have an NCR assigned to it. These reports are much stricter in nature than a simple punchlist item. Punchlist items can possibly be informally negotiated; however, an NCR must have formal documentation of the corrective action that was taken before it is officially signed off on. There should be an NCR log that contains where, when, and what is not conforming to the contract. There should be a column for resolution as well as formal sign-off. This report is a living document, and each item must be resolved before final payment is made. Every project meeting should have an agenda item that addresses NCRs. These items must be addressed as they occur and not be “saved up” until the end. 13.2.11.6 Close-Out Finishing the job can be a very cumbersome task, especially if “minor” activities are left until the end of the project. On most construction jobs, close-out may be completed by personnel that had little or nothing to do with the actual construction. The key personnel have very often moved on to the next project. It therefore may be difficult to resurrect information required to satisfy the owner that the project was built according to the contract drawings and specifications. Storage of all documents must be discussed if not identified in the contract. Will electronic storage suffice or must everything be in paper form? What security will be introduced so no changes can be made after the fact? This is where a good quality control program can pay off. Periodic meetings, quality control, and full completion of individual tasks during the project will make close-out much easier for the constructor, the designer, and the owner. 13.3 CONSTRUCTION ISSUES FOR DIFFERENT TRACKFORMS 13.3.1 Construction Issues for Ballasted Track The purpose of this article is to offer procedures for the construction of ballasted track for a light rail system. Much of this is also applicable to heavy rail and freight and passenger and commuter railroads; however, due consideration must be given to the increased loads and dynamic forces of those other modes. 13.3.1.1 Construction Concept It is important to understand how the track will be constructed in order to ensure continuity and coordination with other constructors. It is also important to understand some basic production rates that may be possible. This can be very important when putting together a baseline

Track Design Handbook for Light Rail Transit, Second Edition 13-24 schedule. What is certain is that the constructor who is doing the trackwork will have appreciably different concepts about how the project can be constructed than those of the designer. Unless there is some definite reason why some portion of the work must be constructed using a particular method or constructed in a particular sequence, the constructor should be given appreciable latitude concerning his “means and methods” so long as the end product meets the requirements. Forcing the constructor to do otherwise will add cost to the project without necessarily adding value or quality. 13.3.1.2 Construction Activities The fundamentals of the art of building ballasted railway track have not changed much since the early days of railroading. We have simply developed better equipment to handle the work. Ballasted track is usually initially constructed in a “skeletonized form,” meaning the two rails have been fastened to the cross ties at the proper gauge distance apart, but no ballast has been placed. This skeleton track is roughly aligned and then the ties are surrounded by ballast stone that will hold it in place vertically and horizontally. The track is then raised, brought to final alignment, and the ballast stone tamped (compacted) to hold the completed track in alignment. The discussion below will explore this basic construction process in more detail. This is not intended to be an all-inclusive list and is primarily directed toward designers so they may have a better understanding how their designs can affect construction. 13.3.1.2.1 Surveying A competent survey party must be incorporated into the project. It is generally advisable to pre- qualify at least the survey party chief since many highway survey parties have not been trained in railway stakeout, particularly turnout geometry and spiraled curves. Pre-qualifying and training survey parties are essential to prevent misalignment and elevation problems. Some of the surveying issues that often arise on projects include the following: • Spiraled curves can be particularly troublesome for an inexperienced surveyor. This becomes particularly critical in direct fixation and embedded track where the surveyor must be able to set grade not only for the low rail of the curve, but also for the outer edges of the track slab formwork. • The survey party must understand all the control points of a turnout, what they are properly called, and exactly which points the track constructor needs to position the track materials on the ground. Confusing the point of intersection of a turnout (PITO) with the point of switch (PS) can be devastating to the project. Very often, the constructor doesn’t need the PITO for construction and would much rather have the surveyor provide reference stakes for the PS and the point of frog instead. • The survey party must understand the difference between the edges of the subballast layer and the edges of the subgrade. If the subgrade is staked and constructed to the width shown on the drawings for the top of subballast, embankments will be too narrow to both support the ballast section and provide a walkway at the ballast toe.

LRT Track Construction 13-25 13.3.1.2.2 Handling Material All track material must be handled properly and the constructor should prepare and submit a material handling plan for every component. This plan should include the equipment to be used and the method of rigging as well as the type and size of the dunnage separating the layers. A storage area plan should be submitted showing the location of all types of material as well as service roads and equipment staging. Each item must be packaged correctly for the equipment and rigging that will be used. Some issues with handling material include the following: • Continuous welded rail (CWR): CWR must be handled correctly by an experienced and pre-qualified equipment operator. If handled incorrectly, the CWR can be bent, flipped, or damaged. A simple nick in the rail can cause a break when the rail is in tension in cold weather. When CWR is in a stockpile, the dunnage between layers must be vertically in line so no bending stress is imposed. Improper placement of dunnage can cause permanent vertical bends in the rail that must be cut out. CWR is very flexible, and it is tempting to laterally shift it more than it can handle, which can cause a permanent lateral bend that must be cut out. • Cross ties: There have been many examples of ties failing long before their expected service life due to improper handling during construction. Concrete ties must be stacked with dunnage in the rail seat area so as not to cause bending stresses. Wood ties are typically bundled in numbers that can be handled by the equipment used. If bundles of ties are stacked, then the dunnage used must be sufficiently thick so that forklift equipment can get between stacks without banging into the ties. • Packaging: How material will be handled has a direct effect on how it should be packaged. Even in the case of owner-furnished materials, it is advisable to have the constructor liaise directly with the supplier on issues of packaging and delivery schedule since that can save time and money for all parties and also reduce the possibility of damage to the products. “Other track material” (commonly abbreviated as OTM), such as rail fastenings and fasteners, can be placed in crates; however, the crates must be substantial enough to accept the equipment doing the unloading and the weight of the material inside. • Long-term storage: Even though track materials are intended for outdoor use, they can deteriorate in storage if not stacked properly. The corrosive effects of acid rain can be particularly damaging to closely stacked rail. Air should be able to circulate around the rails so any moisture can easily drip off and evaporate. The usual practice of tightly stacking rails with the bases touching can hold moisture in the stack and initiate corrosion, particularly if falling leaves accumulate in the spaces between the rail webs so that snow and ice is held against the rail base and web. If rails will be stored for more than a year or two, consider spacing the rails in each tier ½ inch [about 1 cm] apart so storm water is more likely to drain through. Groove rails should always be stacked with a slight pitch from one end of the pile to the other so that storm water will not lay in the flangeway. Covered (but not necessarily indoor) storage can go a long way toward keeping track materials in good condition.

Track Design Handbook for Light Rail Transit, Second Edition 13-26 13.3.1.2.3 Underground Systems Construction Even once earthwork has been completed to create the trackbed, it is not yet time to begin track construction. First, prior to installing the subballast, the constructors responsible for the installation of underground electrical ductwork and manholes should be required to complete as much of their work as possible. This, in some cases, includes direct burial cables. Similarly, catenary pole foundations and the underground portions of other vertical construction (such as the foundations for signals) should be installed prior to the placement of subballast. If these items are deferred until after track construction has commenced, the subballast and ballast will be disturbed and contaminated with subgrade materials, very likely creating locations in the track that will be maintenance headaches for decades. To avoid these problems, it is highly desirable that the contractors who will be constructing these underground systems elements be on board and mobilized before track construction commences. However, in many instances, the train control systems, traction power systems, and other electrical networks that will require underground conduits have not even been designed when the civil constructor begins grading and excavation. This very often leads to trenching for underground ducts well after the track is constructed. Any such excavation within the trackway after the track has been built will cause problems. If the subballast is compromised with inappropriate backfill material or an underlying geotextile layer is punctured or destroyed, it is very difficult to restore the original integrity of the track’s substructure. Settlement of the track and contamination of the ballast, both of which interfere with proper drainage, will result and ultimately reduce the service life of the track structure. For these reasons, the track designer should strongly encourage the construction of all underground ducts prior to the placement of the subballast. For just this reason, some transit agencies utilize separate “systems elements” contracts to install as much of the underground ductwork as possible prior to the construction of tracks. The empty ducts and manholes are then turned over to a systems contractor for the installation of cables and final connections to signals, bungalows, and other above-ground systems infrastructure. If, as is often the case, some of these systems elements simply cannot be installed ahead of the track construction, it is essential that the contract that will install them includes specific specification language concerning how the track subballast and ballast are to be restored, including compaction and tamping requirements. Even then, it is also often necessary to take extra effort to impress upon the constructors of these systems, as well as the construction inspectors monitoring their work, the absolute importance of correctly restoring disturbed portions of the track. Specifications notwithstanding, in the absence of close oversight by the trackwork side of the project (including the designer, the track constructor and any construction manager overseeing the track construction), it is highly probable that the track will not be properly restored after underground systems construction. 13.3.1.2.4 Placement of Subballast The placement of the subballast layer is typically performed using a spreader box that defines the edges of the aggregate and screeds it to proper grade. So that the finished elevation of the subballast is within tolerances, it is essential that the subgrade on which it is placed is properly shaped and compacted. Subballast should not be placed on subgrade that is rutted, crisscrossed with trenches full of uncompacted backfill, frozen, or muddy. Once the subballast has been

LRT Track Construction 13-27 placed, it needs to be compacted to the specified density and the finish elevations verified. Compaction is usually done with a vibratory roller, the larger the better. Once placed and compacted, the operation of rubber-tired vehicles over the subballast should be extremely restricted. It is essential that any ruts or other damage to the subballast be repaired prior to it being covered with the initial layer of ballast. 13.3.1.2.5 Layout Rail and OTM When to layout the rail and other track material is a decision that must be well thought out. Laying out the CWR too early can result in damage to the rail. If other contractors subsequently need to access the right-of-way, they might drive their equipment over the loose string of rail. If the rail is not firmly supported, their trucks may bend or damage it. If one of those trucks flips the rail, someone who is standing near the rail ¼ of a mile [400 meters] away could be seriously injured or even killed. If other contractors attempt to do excavation under the rail, it could be damaged by the excavator bucket. Laying out clips, bolts, spikes, or any other OTM ahead of the track construction can also be cause for damaged, lost, or stolen material. These activities must be well thought out and incorporated in the action plans. Each activity must have assigned equipment, tools, material, and timing. 13.3.1.2.6 Spread Initial Layer of Ballast Raising track up through dumped ballast places significant stresses on the rail fastening system. So as to minimize those stresses, it is good practice to limit the actual raising of the track. This is achieved by placing most of the ballast below the ties prior to the construction of the skeletonized track. This layer of “bottom ballast” is placed and compacted on the subballast, with the top surface about 2 to 4 inches [50 to 100 mm] below the final elevation of the bottoms of the cross ties. This is easily accomplished using conventional road building equipment such as a spreader box and bulldozer or motor grader. Once this bottom layer of ballast is brought to the proper elevation, a drum roller should thoroughly compact it so that the ballast particles are firmly interlocked and the surface is planar and unyielding. This interlocking of ballast is critical for the stability of the track under thermal and dynamic forces. Once the bottom ballast is placed and compacted, care must be taken not to rut the ballast surface causing the ties of the skeleton track to have an uneven bearing. 13.3.1.2.7 Place (Bed) Cross Ties Concrete Ties: Placing concrete ties requires equipment since a concrete tie can weigh up to 850 pounds [385 kg]. There are a number of types of equipment to handle these ties: • There are attachments to standard excavating equipment that can handle eight ties very easily and space them correctly. • There are spreader beams with hanging cables spaced to match the correct tie spacing. • There are “boom trucks” (sometimes called “log trucks”) equipped with grapples that can handle concrete ties. • A front end loader with forks can be used. • Track-laying machines have conveyance systems to correctly place and space the ties on a prepared layer of ballast.

Track Design Handbook for Light Rail Transit, Second Edition 13-28 Whichever method is chosen, it is imperative that the concrete ties lay flat and do not have ballast bearing at their centers as this will cause the ties to crack later in the process. Some ballast screeding equipment compensates for this by creating a slight concave depression along the center of the track. There should be full bearing between the bottoms of the ties and the bottom ballast layer for about 14 inches [35 cm] each way of the tie’s rail seats. Wood Cross Ties: Wood ties, being much lighter than concrete ties, can be handled much more easily, including manually by workers using tie tongs. A log truck with a grapple is a popular method for handling wood ties. The ties can be roughly spaced on a prepared ballast layer by the log truck and then properly spaced using tie tongs. Wood ties are more “forgiving” than concrete ties when placed on uneven surfaces. Other Types of Ties: Steel, plastic, and composite ties can be handled and placed much like the wood ties. They are usually lighter in weight, and therefore more pieces can be moved with the same equipment. They must still be placed at the correct spacing and alignment on the prepared subgrade or ballast layer. 13.3.1.2.8 Set Up Line Side If wood or plastic ties are chosen, they can be pre-plated. Pre-plating carries some risks and challenges in order to create the gauge and cant correctly based on the size of the rail. Using the same dimensioning for 115-pound rail as 136-pound rail will not work and will create either wide or tight gauge when the rail is set. If pre-plating is not chosen, one plate needs to be set toward one end of the tie in the correct position. This activity is called “setting up line side.” This offers a control when setting the rail into the plates. Quality control is an important part of getting this right. 13.3.1.2.9 Gauge Track If using concrete ties or steel ties, then the fastening system is already incorporated in the manufacturing process and track gauge is generally fixed. In most cases, only spot checking or gauge is needed. Some concrete cross ties allow a small amount of gauge adjustment by changing out the plastic rail insulators beneath the rail clips. When using timber ties, the second rail must be correctly gauged relative to the first rail after it has been secured. The ties can be pre-plated using a jig to set the plates to correct gauge, but even then, the gauge should be verified during rail laying. In general, it is not necessary to check gauge at every tie. Assuming the use of new rail that meets specifications, gauging every fourth tie is usually adequate in tangent track and flat curves. Sharper curves need to be gauged at closer intervals. Extremely sharp curves may need to be gauged at every rail fastener even if the rail is precurved. When gauging track, it is imperative that both rails are seated properly into the plates with the correct cant. Setting gauge with the rails canted wrong will cause tight gauge after the rail becomes seated. Just one tie plate that is backward can cause incorrect gauge in 20 feet [6 meters] of track. 13.3.1.2.10 Pre-Line and Clean-Up After the track has been constructed in a skeletonized form, it is advisable to pre-line the track to within 1 inch [about 2 to 3 cm] or so of theoretical. This helps follow-on operations and will ensure the right amount of rail is in the track. Making dramatic alignment adjustments after the ballast has been placed can introduce compressive or tensile forces in the rail, which could prevent the

LRT Track Construction 13-29 track from ever staying in proper alignment. Then, the only way to fix the problem is to cut the rail and add or subtract rail as necessary. The same sort of problem can occur if the top of the bottom ballast layer is not a reasonably uniform distance below the final track profile. A general clean-up of the track prior to ballasting will prevent both valuable track material and debris from becoming lost in the ballast. 13.3.1.2.11 Dump Top Ballast The next step is to introduce more ballast into the skeleton track structure. The ultimate goal in this step is to have a cross section that has the ballast up to the top of rail and a robust shoulder. This “top ballast” is generally placed up to the top of the rail and continues at that elevation to a point about 12 inches [30 cm] beyond the ends of the ties, where it slopes down to the trackbed. If the bottom ballast was placed correctly, more ballast than this should not be required to achieve the finished ballast cross section. During the placement of the top ballast, it is imperative that no equipment apply pressure on top of the ties even after the ballast has been placed. This will dislodge the fasteners if the tie is not 100% supported underneath. There are several methods for placing ballast into the cribs and shoulder of the track, but, in general, only on-track equipment should be used. Top ballast can be placed with standard bottom dump railroad hopper cars or hy-rail dump trucks. Some contractors have low platforms with rail wheels that are large enough to accommodate a standard dump truck loaded with ballast. These are towed by a small locomotive to ferry dump trucks to and from the ballast placement site. If site conditions permit, ballast can also be placed from the side of the track with standard heavy construction equipment such as front end loaders. However, rubber-tired vehicles without hy-rail gear should never be driven on top of the track. Too much damage can be done; for instance, the rail can be gouged. If a nick is in the rail, it is considered a defect and therefore must be replaced. The ties could be damaged or dislodged from the fasteners. The ties could crack under load, but the damage might not be apparent for years. 13.3.1.2.12 Raise, Line, and Tamp Track This step in the production of a good ballasted track requires some specialized equipment specifically designed for raising the track out of the ballast up to the correct grade, positioning the track laterally to exact alignment, and then tamping the ballast. So as to minimize strain on the rail fastening system, this should be done in at least two lifts, each not more than 3 to 4 inches [25 to 75 mm], with the final lift being no more than about 1 inch [25 mm]. All automatic tampers work on the alignment relationship between a light projector and a shadow board receiver positioned a specified distance away. This geometric relationship is what produces finished track within very tight tolerances. The ballast should be tamped under the ties for 14 inches [35 cm] on either side of each rail but not the middle of the tie. Ties should never be tamped in the middle except at road crossings, where the ballast is captive. Over time the ballast will migrate to the shoulders, and, if the middle of the tie was tamped, the tie becomes “center bound.” This will cause the tie to crack in the middle, especially concrete ties.

Track Design Handbook for Light Rail Transit, Second Edition 13-30 Extra care must be taken when using these machines so they do not drop the tamping tools on top of a tie, damaging it. It is also necessary to set the depth that the tamper’s work heads go into the ballast. If they are set too high, they will damage the bottom of the tie, especially concrete ties. If they are set too low, they will not tamp the tie tight enough to hold the elevation correctly. The correct setting is when the top of the tamping tool is no more than 1inch from the bottom of the tie. An experienced tamper operator is an absolute must or serious damage could happen that may not be detected until the track buckles or the track settles prematurely. 13.3.1.2.13 Dress and Broom Track This activity requires a ballast regulator, a rail-mounted piece of equipment with the capability to transfer ballast from one side of the rails to the other in order to produce the desired cross section. This equipment also has the ability to “broom” the track, sweeping the ballast to an elevation equal to the top of the tie. Using the “wings,” it can shape the ballast shoulder, which accounts for 35% of the holding power when the rail is above or below the neutral temperature creating compressive or tension forces in the rail. Ballast can be dressed manually using shovels, but, since that process is labor-intensive, it is used on only very small projects. The important aspect is that a consistent cross section must be maintained throughout the length of track. One small area that is weak on ballast shoulder will be a high-risk area for a track buckle during hot weather. Very often, the track vibration caused by a moving train is the instigator of a track buckle that will occur suddenly and only a very short distance ahead of the train. Derailment is the usual result, so track buckling is a very serious issue. 13.3.1.2.14 De-stress and Make Closure Welds De-stressing continuous welded rail is an activity that could jeopardize the stability of the track structure if done incorrectly. Any owner of track who is subject to FRA oversight must have a standard procedure for de-stressing CWR and maintaining the neutral temperature of the rail. Neutral temperature is the temperature at which a rail of fixed length is neither in compression or tension. Determining the neutral temperature is specific to every region and every owner. The neutral temperature could be 95 degrees F [35 degrees C] in Connecticut and 130 degrees F [54 degrees C] in Arizona. AREMA offers guidelines to determine rail neutral temperature based on the highest and lowest rail temperatures experienced at the project site over the previous 50 years. This neutral temperature must be established at the onset of a project. It is also important to understand that the neutral temperature of the installed rail will possibly change if the track is realigned or the profile elevation is changed. That is why thermal de-stressing of the rail should be done only after the track has been brought to the final line and surface and all the ballast is installed and dressed. De-stressing with insufficient ballast in track will not achieve the goal and serious problems will happen later. The amount of compressive force in the rail will vary with the temperature, the cross-sectional area of the rail, and the constrained length of the rail string. A good, well-built, ballasted track can withstand about 187,000 pounds [about 182 kilonewtons] of compressive force. Beyond that, the track could buckle. To avoid this, AREMA says that CWR should generally be anchored at a neutral temperature that is not lower than 50 to 70 degrees F [about 30 to 40 degrees C] below the maximum expected rail temperature. The rail can easily be as much as 40 degrees F [about 22 degrees C] above the ambient air temperature on a hot sunny day, so it is important to understand that for track exposed to sunlight, the daytime rail temperature is virtually never the same as the ambient air temperature in the shade.

LRT Track Construction 13-31 Rarely will the rail naturally be at the optimal neutral temperature when it is time to anchor it in place. It is therefore necessary to adjust the rail so it will be in a zero-stress condition at the target rail temperature. As an example, if 1500-foot [457.2-meter] lengths of CWR are to be anchored at a desired neutral temperature of 95 degrees F [35 degrees C], but the actual rail temperature is 40 degrees F [4 degrees C], the constructor must simulate a rail temperature of 95 degrees before the rail can be permanently attached to the ties. This is done by calculating the gap that is needed between rails at their present temperature so that, when they are heated to the desired neutral temperature, the gap will be exactly closed. The formula (using U.S. traditional units) to determine this is the following: G =0.000078 × L × ∆T where G is the gap between strings of rail measured in inches, L is the length of the rail string measured in feet, and ∆T is the change in temperature in degrees Fahrenheit. When using S.I. units of measurement, the formula is the following: G = 0.117 × L × ∆T where G is the gap between strings of rail measured in millimeters, L is the length of the rail string measured in meters, and ∆T is the change in temperature in degrees Celsius. Solving the equation for the parameters stated above determines that a 6.4-inch [163-mm] gap must be left between strings at 40 degrees F [4 degrees C] so that when the rail is heated to 95 degrees F [35 degrees C], the gap will be exactly closed. However, a dimensional adjustment must be made to account for the rail welding process used to make the closure as follows: • If thermite welding will be used to connect the two strings of rail together, add 1 inch [25 mm] to account for the thermite metal. Hence, the total gap would be 7.4 inches [188 mm]. Some thermite weld kits may require a different dimension, so it is important to consult the kit manufacturer’s printed directions. • If a portable flash butt welder will be used, it is necessary to subtract an amount from the gap to account for the loss of metal as the rail ends are forged together. Typically, the loss would be 1.5 inches [38 mm], so the actual gap would be 4.9 inches [124 mm]. Some welding equipment produces “low consumption” welds that use much less metal, so it is important to understand the equipment being used. The calculations in the example above have been carried out to a precision of 0.1 inch [2.5 mm], but the calculated gap is typically rounded to the nearest ¼ inch [6 mm] increment. Since ¼ inch [3 mm] of rail movement over the length of the CWR string equates to only about a 3 degree F [1.7 degree C] difference in neutral temperature, that is sufficiently close tolerance for practical application. It’s also consistent with the practical tolerances for field measurements and marking.

Track Design Handbook for Light Rail Transit, Second Edition 13-32 In this example, the rounded answer is 6 ½ inch [165 mm]. If the work is being done using S.I. units of measurement, the final answer might rationally be rounded to the nearest half-centimeter. Note that the calculations are dependent on the length of the CWR string and the temperature at which the measurement was taken. Strings will never be exactly some even number length, such as 1500 feet. Even if they were some exact known length at the time of welding, things happen that could have reduced the string length, such as cropping off handling holes on the ends of the string. Therefore, each string length and the temperature at the time of measurement should be measured once the rail is laying loose on the cross ties or rail fasteners. A rolling measuring wheel is sufficiently accurate for this purpose. Once the movement of the rail to simulate neutral temperature has been determined, the rail is marked at its quarter points to monitor rail movement and thereby ensure that proper movement is consistent throughout the entire string. For the aforementioned 1500-foot CWR string, each quarter is 375 feet [114.3 meters]. To ensure that the rail is moving uniformly, apportion the 6 ½ inches [165 mm] of total rail movement into the rail’s quarter lengths. Mark the desired movement at each quarter point on the rail, concurrently making matching marks on the rail and the rail fastener or a cross tie beneath it. Therefore, at the first quarter point there should be 1 ⅝ inches [41 mm] of movement, at the second quarter there should be double that, or 3 ¼ inches [82 mm] of movement (i.e. ,1 ⅝ inches + 1 ⅝ inches). At the third quarter there should be three times the movement at the first quarter point, i.e., 4 ⅞ inches [124 mm], and at the last quarter the full 6 ½ inches [165 mm] of movement. Before marking these measurements on the rail, it is essential to first relieve any residual internal force in the rail. This requires unclipping the rail from the cross ties (or rail fasteners) and, by using rollers (beneath the rail) or rail vibrators (attached to the rail), eliminate any friction that is between the base of rail and the rail seats. This is a very important part of the procedure. Only once the internal forces have been released should the calculated movement be physically marked at each quarter point. The rail length is then adjusted to close the gap and achieve the desired movement at each quarter point. This is typically done by beginning at one end, where the string has already been attached to a previously anchored string. Adjustment is performed by either heating the rail or by pulling on the ends of the rail or a combination of the above, typically pushing the string toward its free end. Various types of equipment are used for both heating and pulling. Whether heating or pulling the rail, the quarter point movement must be achieved or the de-stressing processes will not be completed properly and a higher risk of a track buckle is prevalent. Once the predicted quarter point movement is achieved, the desired gap is achieved by cutting the free end, if necessary, to match a fixed point such as another previously anchored rail or a special trackwork layout. The rail fastenings can be reinstalled and the closure weld installed. The procedure above is generic, and some owners may have slightly different procedures or formulae. It is therefore advisable to consult each property’s CWR plan. For example, some track owners prefer to do all of the calculations in inches and therefore use a coefficient of expansion of 0.0000067 in the U.S. units version of the formula. Some owners will simplify the process for field personnel by providing tables that may require extrapolation.

LRT Track Construction 13-33 It is essential that the two rails of a track be anchored at very nearly the same neutral temperature. A tolerance of plus or minus 5 degrees F [3 degrees C] is usually specified. 13.3.1.2.15 Install Insulated Joints and Other Appurtenances It may be common practice for some contractors and agencies to install insulated joints after the rail has been de-stressed. If this is the case, it is extremely important to not add or subtract rail because this will change the neutral temperature. Each field thermite weld introduces 1 inch [25 mm] of rail into the system. This must be accounted for when welding in insulated joint plugs. If more length is introduced, the risk of a track buckle increases. Always keep in mind that a track buckle will very likely cause a derailment. 13.3.1.2.16 Clearing Ballast from under the Rails Traction power return current in the rails is searching for ground. Some amount of the current will follow routes other than the rail in an inverse relationship to the electrical resistance of that path. This is stray current. The ballast is a slight conductor. Wet ballast is even more so and muddy ballast can be much worse. It is therefore important that ballast not touch the rail. If ballast continues to touch the rail, the track-to-earth resistance test will generally fail. Therefore, the ballast in the cribs between the cross ties must be removed from under the rail, usually to a minimum clearance of 1 inch [25 mm] between the top of the ballast stone and the underside of the rail or any other metallic part of the track structure. This is commonly called “poking” the ballast and can be achieved by using a track shovel to push the ballast from beneath the rail. Some contractors have adapted other track construction equipment (such as a rail anchor applicator) to do most of the work of pushing the ballast out from under the rail, but manual methods of final clean-up and disposal of surplus ballast are usually necessary. Poking the ballast is not necessary on non-electrified railways; therefore, unless it is clearly called out in the contract documents, the track constructor may not realize it is a requirement and may demand a change order to cover associated labor and equipment costs. Another activity that can provide better insurance of passing the electrical isolation testing is to use compressed air to blow any ballast fines off the rail fastenings. Ballast fines, when mixed with rainwater, can result in a “paste” that coats the rail fastenings and provides a conductive path to ground. 13.3.1.3 Some Lessons Learned the Hard Way There have been some very important lessons learned during the design and construction phases of a light rail system. It can be a valuable tool to understand during the design phase of a project. We have an obligation to learn from our mistakes and to share them with the industry. The ultimate user of these systems must be safe, and the designer and constructor have the responsibility to deliver this to the owner. • Placing ties on uneven surfaces: When ties are placed on an uneven surface in a “center bound” condition, they may break under the weight of the rails and track construction equipment, particularly ballast trains and rail trains, if used. Concrete ties are very susceptible to this. On more than one project, hundreds of concrete ties had to be replaced.

Track Design Handbook for Light Rail Transit, Second Edition 13-34 • Not poking ballast: If the ballast is touching the underside of the rail, the electrical isolation test will fail. Failure of the test is typically cause for an NCR. As mentioned above, the ballast must be removed from under the rail. • Using ballast with excessive fines: When ballast comes from the quarry, there may be a certain amount of fine particles remaining. If the fine particles are excessive, they may block the proper drainage of the ballast section, and over time this will cause premature degradation of the ties and the track structure as a whole. Fines can also make it more difficult to achieve electrical isolation. It is imperative to follow proper specifications for delivery and handling of ballast. When ballast is stockpiled, fine particles will migrate to the bottom of the pile. If these fine materials are loaded into transporting trucks or cars, they become part of the track structure. If the stockpile methodology is used, the bottom 4 to 6 inches [10 to 15 cm] of the pile may need to be sacrificed in order to ensure the integrity of the track structure. • Not documenting de-stressing: When de-stressing rail, there must be good documentation in the form of paperwork as well as markings on the rail. Quarter point markings, including the supervisor’s initials, the date, the rail anchoring temperature, and the actual movement should be done in permanent paint. Not having proper documentation will lead to speculation as to whether it was done properly. These records must be maintained and passed on to the Maintainers after the system begins revenue service. If an incident happens sometime later and rail de-stressing is suspected as a cause, the absence of documentation could lead to unpleasant litigation. 13.3.2 Construction Issues for Direct Fixation Track The purpose of this article is to offer procedures for the construction of the Direct Fixation Trackform. Many procedures have been used, and many have failed. This discussion will identify the advantages and disadvantages of those methodologies and offer a road map to the successful completion of direct fixation track. 13.3.2.1 Design Concept The designer typically does not have responsibility for decisions pertaining to construction methods; however, it is important for the designer to understand the construction difficulties and pitfalls that could be inherent in certain designs. It is also important to understand that constructors have certain means and methods that they have used on similar projects and are therefore comfortable with, as they expect the same outcome. This article highlights issues that may mean the difference between a success and a failure in track construction and maintainable versus hard-to-maintain once it is in operation. Direct fixation track is a very viable design and easy to maintain if it is built properly. This article will offer the designer some guidance for producing the preferred system that will last for many decades. 13.3.2.1.1 Plinth The word “plinth” simply means a pedestal. In the context of direct fixation track construction, it is a support platform for the rail and other items necessary for a train or LRV to travel upon a guideway. A plinth can be constructed on top of a slab on grade (including a tunnel invert) or on an elevated concrete structure. Use of plinths is particularly well suited for “top-down”

LRT Track Construction 13-35 construction methods since it is placed after the invert is poured, and the fastening devices or inserts are surrounded by the plinth concrete. 13.3.2.1.2 Inserts in Invert When inserts are placed in the invert or slab concrete, the most direct construction method is “bottom up”. The anchor inserts for the direct fixation rail fasteners are generally placed by drilling into the base concrete and installed using cementations grout or epoxy. The inserts can sometimes be supported by templates while the slab concrete is placed. With either method, the inserts must be normal to the top surface of the concrete surface (with some tolerance) so that the assembly isn’t loaded eccentrically when the anchor bolts are tightened. 13.3.2.2 Rail Cant and Superelevation The following is a discussion and definition of cant, unbalance, superelevation, and cant deficiency from a constructor’s perspective. It is important to all parties involved that they use the same terminology throughout the project. Many get confused when terms such as “rail cant,” “cant deficiency,” “superelevation,” “cant,” “unbalance,” “underbalance,” “surface,” “elevation,” “line,” and “alignment” are used. These terms are listed and explained below: • In North America, “rail cant” and “cant” mean the same thing. This is the relationship between the plane defined by the tops of both rails and the vertical axis of each rail. Most often, the rails are pitched inward at a 40:1 slope. Why the rails are canted is discussed in other chapters of this Handbook, but what is important during construction is making certain this relationship is maintained throughout the track system, including tangent, curved, and superelevated track. When using standard timber or concrete ties, getting the rail cant correct is automatic. It is more difficult to achieve in direct fixation track since the rails are anchored to the invert independently. Similar issues can occur in embedded track, depending on the trackform. When laying rail in extremely sharp curves, the head of the rail may curl toward the outside of the curve and result in loss of proper rail cant. Attempts to force the base of the rail down into the rail fastenings can damage both the rail and the fastenings. In extreme cases, it will be necessary to precurve the rails, including cambering, so they sit in the rail fasteners with the correct cant. • “Superelevation” (which is sometimes called “cant” in other parts of the world) is a stand- alone term that describes the relationship between the two rails as one is raised higher than the other. In general, the constructor is concerned only with actual superelevation (Ea) as called out on the contract drawings. Unbalanced superelevation (Eu) is solely the responsibility of the designer and does not represent anything that the constructor must build. • “Surface” and “elevation” are used together and generally mean the same thing with the exception that “track surface“ usually includes consideration of cross level differential between the two rails. Track elevation is the vertical position of the top of one rail. In most cases, it represents the elevation of the inside or low rail in a curve; however, some properties rotate the track about its centerline. This is sometimes used in tight clearance tunnels. If this method is used, it must be clearly identified on the construction drawings. Most Contractors will use the term “surface,” and most engineers will use the term “Elevation.” A meeting of the minds would be a wise choice prior to starting a project.

Track Design Handbook for Light Rail Transit, Second Edition 13-36 • “Line” and “alignment” mean the same thing. This is the physical path that the track will follow. It is generally based on the centerline of track or the center distance between both rails based on the properties property’s standard gauge. In cases where the track gauge is widened (or narrowed) in curves, the contract documents must designate which rail will remain at a constant horizontal distance from the track centerline. 13.3.2.3 Preparatory Work Preparing for design and construction is as important as construction. Answering all the “what-if” questions is absolutely imperative to the success of any project. Once the construction begins, it should continue to the end without interruptions. Discontinuity is the constructor’s nightmare. The following discussion offers a list of activities that should be resolved prior to beginning construction. 13.3.2.4 Top-Down Construction (Recommended) This article is not intended to be a procedure for the constructor to follow. It is meant to inform the designer of certain activities that should be followed. The constructor should present their procedure to the designer prior to construction commencement, and the designer should be prepared to present “what-if” scenarios that could result in unacceptable quality. Those scenarios should always be resolved before any construction begins. 13.3.2.4.1 Check Guideway Once the guideway or invert slab is completed, it must be prepared for the placement of more concrete on top. This may require water blasting to remove any laitance or curing compound in order to achieve a good bond between both sections of concrete. It would be advisable to inspect the surface of the guideway or structural slab and correct any defects. Dowels (also known as “stirrups” or “rebar hoops”) are reinforcing steel that project out of the base slab and provide an anchorage for the reinforcing steel in the plinths. The stirrups must be installed in line with the rail. Traditionally, they have been installed parallel to the rail, but it is actually advantageous to install them perpendicular to the alignment. This will allow for the least possible interference with the direct fixation rail fastener anchor inserts. If an insert falls too close to a transverse stirrup, the rail fastener spacing can be easily adjusted to remove this interference. However, if the stirrups are placed longitudinally and conflicts occur, they may need to be removed and reinstalled. That requires drilling into the invert slab and the potential for hitting embedded reinforcing steel is high. Also, since the conflict is typically not identified until plinth construction is well under way, the corrective action delays the overall work. The simple placement of the stirrups in the traverse orientation can therefore save a great deal of re-work and time. 13.3.2.4.2 Rail/Plate Support System The objective of a support system is to set the two rails of the track to the exact gauge, alignment, surface, cant, and cross level prior to placing the plinth concrete. Development of a support system for the suspended rails and/or fastener plates is potentially the most important task of the project. It will certainly set the pace of construction and the quality of the finished product. If the wrong system is chosen, re-work is necessary, including possible demolition of new concrete. There will be many crafts involved in the construction of the plinths and the subsequent installation of the rail fasteners and rails, and representatives from each should be involved in

LRT Track Construction 13-37 devising the support system. Including them will bring out the problems that may be encountered so that solutions can be made prior to the construction. If an actual section of rail is used as a template, it is very easy to set these parameters. The first decision to be made is whether the permanent CWR will be used as the guide or separate template rails will be used. It is important to understand that when working in direct sun light, the rail will expand and contract. If 1400-foot [about 427-meter] CWR strings are used to support the rail fasteners in position, it must be understood that every 5 degrees F [3 degrees C] of temperature change will produce a ½ inch [12 mm] of rail movement. If the inserts are attached to the fasteners, and the fasteners are firmly attached to the rail, the expanding rail will drag the inserts through the wet concrete, causing voids on one side of the inserts. In contrast, if 300-foot [91-meter] rails that are anchored at their mid-points are instead used as construction templates, the extreme movement would be only 1/16 inch [1 mm]. With this factor in mind, contractors have devised several approaches. These include gantry type systems. Others have used special rail clips that release the rail fasteners from the rail once the concrete has taken an initial set but before the rail temperature changes by any significant amount. Once the rail is set, everything that is attached to the rail is automatically set in the proper orientation also. These template rails can be used over and over. 13.3.2.4.3 Handling Material This is another decision that must be made early. Does the material get distributed in advance of the plinth placement or follow after the concrete is placed? If the actual direct fixation rail fasteners are not used as the holders of the inserts, they may just be in the way when concrete is being placed. If in a tunnel environment, temporary or permanent hatches to street level may be required in the roof structure, or hy-rail equipment may be the only way to distribute the material. Tunnels that include sharp curves can be a particular challenge for movement of materials. The constructor should be required to address these issues early so continuity of construction activities is achieved and material is not destroyed by other activities. Vandalism and theft may need to be brought into the discussion also. 13.3.2.4.4 CWR Will the CWR be placed in advance of the plinth placement or after the plinth placement? If laying out the CWR in advance, certain considerations must be thought out. The CWR may buckle unexpectedly and injure a construction worker. It may simply get in the way of other activities and be moved aside by another contractor without the proper tools or experience. Other trades frequently do not understand that even a “slight” nick in the rail can be a serious defect. On one project, a surveyor placed cross cut chisel marks in the head of the rail for reference points. He had no idea that such chisel marks are the first step in a time-honored method of cutting rail without a saw. He also didn’t understand that even well-constructed track is subject to measureable movement due to loading and thermal effects and hence makes a poor reference point for surveying. After the plinth is poured, a piece of equipment will be required to get the CWR into the fasteners. This can be achieved with laborers, but certain safety precautions must be adhered to so as not to damage or flip the CWR. Pushing the rail on top of the fasteners after the plinth has been placed will require a hy-rail piece of equipment equipped with 360 degrees of motion. Any

Track Design Handbook for Light Rail Transit, Second Edition 13-38 longitudinal movement of the rail requires rollers be placed under the rail. Whichever method is chosen, it must be well thought out. 13.3.2.4.5 Some Recommendations on Packaging The way in which materials are packaged can affect the continuity of the work and the safety of the workers. Packaging should always consider how the packaged materials will be handled, including the equipment that will be used. For example, different packaging might be required for forklift handling versus crane handling. If a decision is made to layout fasteners in piles every 50 feet [15 meters], pallets could be assembled with the correct number of fasteners to accommodate that length of track. This logic should carry through to all material, such as bags of clips or bolts and washers. However, the way material is packaged must also match the equipment doing the unloading and distributing. The constructor must match the equipment to the packaging and, if possible, coordinate with the suppliers to match the packaging to the construction and handling methods. This all should be identified in the construction work plan furnished by the constructor. 13.3.2.4.6 Welding Rail The flash butt welding process is the most common to produce CWR. The CWR strings are then welded together after the de-stressing activity is completed by the field weld process. Determining whether to fabricate the CWR strings onsite or off-site is governed by several considerations, including whether the rail is procured by the owner or the constructor. Off-site welding presents some challenges concerning delivery. It’s obviously only possible if there is a rail connection between the welding site and the construction site, since CWR is delivered by special rail trains. An evaluation must be made with respect to loading of the LRT structures. The axle loads of a rail train designed for freight railroad service is much greater than LRT, possibly by a factor of three or more. Also, the rail train might be incompatible with the curve radii, gradients, and perhaps even the track gauge of the LRT line. Cost-effectiveness will play a role in this decision, bearing in mind that the rail train delivery cost is usually on a daily rate and includes not only the time in transit from the welding plant to the job site, but also portal-to- portal time from some home terminal plus the time while it is being loaded and unloaded. Because of these factors, most transit projects set up a portable rail welding plant, usually somewhere along the project site or at a convenient location along some existing segment of the LRT system. Setting up a portable welding plant is easy to do as long as there is enough length to stockpile the string lengths chosen. Welding onsite gives the flexibility of placing piles of CWR in strategic areas for later distribution. The welding site(s) must be accessible for delivery of the stick rail in lengths of 78 to 82 feet [24 to 25 meters]. 13.3.2.4.7 Surface Preparation The concrete invert for the direct fixation track (i.e., bridge deck, tunnel floor, or slab on grade) must be clean and free from chemicals that could prevent a good bond between the invert and the plinth concrete. The invert should also be roughened (“scabbled”) to achieve a good bond. High-pressure water blasting is frequently used. The use of epoxy bonding agents, which was previously popular, is not recommended since their coefficient of thermal expansion can differ appreciably from that of the concrete.

LRT Track Construction 13-39 Dowels/stirrups projecting from the invert need to be straight and clean. If epoxy coated, their coatings should be checked and touched up as necessary before subsequent construction makes them difficult to access and inspect. 13.3.2.4.8 Setting the Track Setting both rails to the correct orientation is the essence of “top-down” construction. This can be accomplished by using a support system that holds each rail in correct alignment, gauge, and cant. The supporting system must be sufficiently robust to withstand both casual loadings and more severe impacts from workers and the subsequent construction activities. An example is the mass of a concrete pumping line and the pressure exerted by concrete flowing out of the hose. The supporting system should generally be external to the finished concrete. However, jigs are available that are supported on smooth tapered rods. The rods can be positioned within the plinth formwork, embedded in the pour, and then easily withdrawn from the green concrete. The resulting holes in the concrete must be patched correctly, especially in a region that experiences freeze/thaw cycles and preferably before they become filled with construction debris. The supporting fixtures should be capable of making adjustments. If the cant of both rails is 40:1, that parameter can be fixed. If the rail cant is deliberately varied so as to help wheel set steering, adjustments can be built into the jigs to accomplish that. If the gauge is fixed and does not need adjusting, correct gauge can be built into the system. There should be a means of adjusting elevation on both rails as well as alignment referenced from centerline of track or line side. Line, Grade, Gauge, Elevation, and Cant: Setting these distinct parameters prior to placing concrete will greatly facilitate the success of a project. If this is accomplished correctly, the need for subsequent adjustments for tolerances will be dramatically minimized. Attach Fasteners and Inserts: Once the rails have been set to the proper orientation, either the fasteners or accurate anchor insert templates can be attached to the rail. Use of the rail fasteners ensures accurate placement and saves the step of later removing the templates to install the permanent rail fasteners. However, it also subjects the rail fasteners to possible damage ranging from concrete spillage up through more serious harm. The constructor’s work plan should address this topic directly so as to avoid disputes. The remainder of this discussion presumes the use of the rail fasteners as opposed to templates, but the principles are the same. If the fasteners are fabricated with the rail cant built in, the plane surface defined by the bottom of the fastener will be the same for opposite fasteners. A simple check for cant is to place a 6-foot [2-meter] straightedge along the bottom of opposite fasteners. If there is a space anywhere along the straightedge, the cant is incorrect. If the rail is to be canted, but the fasteners do not provide cant, there should be a consistent gap above the straightedge on the field side of the fastener. This geometry must be closely watched during construction as a quality control checklist item. Once the fasteners are attached to the rail, the inserts will be attached to the fastener by using a temporary bolt snugly holding the insert tight against the underside of a steel shim plate placed between the fastener and the insert. This temporary steel shim should be at least ⅛ inch [3 mm] thick and 1 inch [25 mm] larger in each plan dimension than the footprint of the fastener. This steel shim (also known as a “slobber plate”) provides a smooth flat bearing surface on the

Track Design Handbook for Light Rail Transit, Second Edition 13-40 finished plinth for the rail fastener. The steel shim also prevents concrete from entering the voids on the underside of the direct fixation rail fastener. Using a plastic shim for this purpose is not recommended because the flexible properties of the plastic and its likely deformation (especially when hot) means that the finished concrete surface will likely not be a flat plane—making excessive grout repairs necessary. Thin layers of grout are not likely to withstand the repeated impact loadings from the rail fasteners, so it is strongly recommended to avoid construction methods that may require them. The fasteners should not be attached to the rails using the permanent spring clips since thermal movement of the rail could drag the fastener inserts through the concrete. Instead, temporary clamping devices that have a point load on the base of rail should be provided. The only function of these devices is to hold the fastener plate firmly to the rail base during plinth construction. They should be released as soon as possible after the concrete has achieved an initial set. Other templates can be designed to hold inserts that may be used for an emergency guard rail or other hardware. As long as the geometry is calculated correctly, the inserts will be in the proper orientation for installing other attachments. The reference must be the running rail. Install Reinforcing Steel: Installing the reinforcing steel or “rebar” can be done either before or after the rail is set. It would be wise to do a risk analysis on both methods to achieve the safest result for the workers with the best assurance of quality. The important aspect of this activity is to not move the rail out of alignment and to avoid contact with any embedments. When performing “top down,” it is relatively easy to achieve a 2-inch separation between inserts and rebar. The difficult part is ensuring that either ƒ The coating on epoxy-coated rebar remains intact and that all chips and cut ends of the reinforcing steel are properly patched. The rail anchor inserts must be fully coated also, with no chips or “holidays” in the epoxy. ƒ Black steel reinforcing is properly welded/bonded so as to result in an electrically continuous cage. All welds must be checked and the electrical continuity of the rebar cage or mat must be checked. All it takes is one piece of rebar that is not part of the mat to compromise the design, initiate corrosion, and possibly destroy the structure in less than 20 years. There may be test stations associated with this methodology, and they must be checked also. If construction joints or control joints are used in the concrete, continuity must be checked between reinforcing steel on opposite sides of the joints. The objective is that every single piece of rebar in the structure is electrically continuous. Obviously, either approach requires meticulous attention to details, particularly since such methods are not commonly encountered in other types of reinforced concrete. In many cases, even experienced workers installing the reinforcing steel will be unfamiliar with these methods and may not understand the importance of doing the job strictly in accordance with the plans and specifications. Close inspection is therefore required to verify that epoxy coatings are intact or intersecting black steel bars are welded. Quality control checklists are invaluable during this phase of the construction. Concrete Placement and Consolidation: This can be accomplished in many ways. Using a concrete pumping system is the preferred method, but, if access is easy, a crane and a concrete

LRT Track Construction 13-41 bucket can be used. If there is access alongside the track, concrete can be placed directly from the concrete truck. Whichever placement method is chosen, the concrete must be vibrated properly. Typically, the concrete contractor will use an internal vibrator. Some key points to keep in mind: • It is very important that the right vibrator head be used. Because the plinths are usually only 6 to 10 inches [15 to 25 cm] tall, a short vibrator head, one designed for use with shallow slabs, is preferable to the more common 12-inch [30-cm] head. The short head is preferred because a long vibrator head will need to be held at an angle to minimize concrete splashing and thereby will mix more air into the molten concrete. A long vibrator head is also more likely to possibly damage any epoxy-coated rebar. • The vibrator must be used properly. It should be inserted only in a vertical orientation. It should not be dragged so as to move the concrete. Pushing the vibrator under the rail fastener or slobber plate will create air bubbles that become pockets in the surface of the concrete beneath the plates. The vibrator should be placed only alongside the fasteners until the concrete is observed flowing under the plate and out the other side. It should not be left in any area too long as that will cause air intrusion and possible segregation of the cement and aggregate. • The person operating the vibrator must be trained in its proper use. Sometimes, this task is assigned to an inexperienced laborer who has little understanding of what is supposed to be done. A few minutes spent training this worker can save hours of repair work made necessary because too much air was introduced into the molten concrete. It is advisable to have a surveyor on hand who will monitor the position of the track and determine whether the track structure is being dislodged during concrete placement. Any concrete spillage onto the direct fixation rail fasteners or the rail should be cleaned up immediately as part of the concrete finishing activities. Spilled concrete could jeopardize both the electrical and mechanical properties of the direct fixation rail fasteners. While concrete on the rail would likely eventually flake off during LRT revenue service, the resulting dust and debris on the trackway would be a housekeeping problem the owner should not have to contend with. When finishing the concrete, it is important to maintain a flat surface between the fasteners with the finish grade located at the bottom of the steel plate. Remove and Reposition Support System: After the concrete has achieved enough strength to support the rail and fasteners attached, the supporting fixtures can be removed and repositioned for the next section of track to be placed. If temporary template rails were used, their relocation to the next segment may need to be deferred until the concrete has achieved additional strength to accept loads from the rail-handling equipment. It is important to evaluate the loads and strength of the concrete prior to removing the template support system. If CWR is used as the template rail, the concrete strength needs to be sufficient to accept the thermal forces from the rail. If shorter template rails were used, 16 hours is often

Track Design Handbook for Light Rail Transit, Second Edition 13-42 sufficient initial cure time, assuming proper concrete placement and curing procedures were incorporated. In colder weather, this may need some adjustment. If the project is being constructed in an active revenue service line (such as the installation of a new turnout in existing direct fixation track), there will usually be a need to complete the work and restore the track to service as quickly as possible. Some projects have done this using high-early strength concrete with cure times as short as 20 hours. Patch Voids under Fasteners: After the concrete has cured, the temporary anchor bolts will be removed so the slobber plate can be released and replaced with permanent shims (often polyethylene) as may be necessary to achieve exact final track profile. The slobber plates are removed, cleaned, and carried ahead for the next pour. The direct fixation rail fasteners should be thoroughly cleaned at this time to remove any remaining concrete spillage. It is usually necessary to patch the small voids or air bubbles that may have been produced under the slobber plate during concrete placement. If trapped air was under the slobber plate, small voids (usually about 1/16 inch [2 mm] deep and usually no bigger than 1 inch [25 mm] in diameter) will be observed. If this is the case, a cementitious grout product can be used to simply spackle this area. Once the grout has cured, the rail fastener can be reinstalled with shims as necessary. Larger voids, particularly any “honeycomb,” could be indicative of improper concrete handling, should be examined by a structural engineer, and may require that the defective concrete be removed and replaced. If temporary templates were used instead of the actual direct fixation rail fasteners, they will be removed and the permanent rail fasteners installed. If an automatic bolt centering serrated washer was used during concrete placement, this is an easy task. It is very important to index the entire system so the direct fixation rail fastener is installed or reinstalled in the correct location as either it or the template was positioned during placement of concrete. By indexing the plate with a zero adjustment serrated washer, it should be unnecessary to realign or regauge the rails. TCRP Project D-7, Task 11, has addressed direct fixation track in extensive detail. See TCRP Report 71, Volume 6, for more details on bearing area required for the safe support of the rail and fastener. Set CWR: If temporary template rails were used during plinth construction, the permanent CWR will need to be installed. In some cases, it may have been previously staged alongside of the track and will need to be threaded into position from the side. Other circumstances might dictate that it be brought in from the end of the segment. The decision will largely depend on the characteristics of the site, will have been made early in the project, and identified in the constructor’s work plan. The rail will be seated onto the fasteners and temporarily attached to every fourth or fifth rail fastener using zero toe load clips. This will allow for any rail-mounted construction equipment such as hy-rail trucks or rail trains. The details on the temporary rail clips should be part of the construction plan developed by the constructor. Even in the unlikely event that the CWR is set into the rail seats at the correct neutral temperature, full anchorage of the rail should not occur until after the rail fasteners have been

LRT Track Construction 13-43 shimmed to provide the correct rail profile within tolerance and all rail fastener anchor bolts have been properly torqued. Thermal Adjustment: Matching the concrete and rail stresses is an important part of this activity. Thermal adjustment of CWR in direct fixation track is similar to that described above for ballasted track with the following exceptions and cautions: ƒ On an elevated guideway, the guideway must be at a neutral temperature also. If the CWR is heated or stretched too much on a cold guideway, the rail, when it cools and contracts, will introduce forces on the guideway superstructure. These forces could deform the bridge’s support bearings, especially if they are seismic bearings. It is advisable to defer rail thermal adjustment until the temperature of the guideway is close to its natural temperature when the rail is in its neutral state. Concrete and steel have similar coefficients of expansion and this must be taken into consideration when de- stressing rail on guideways. ƒ De-stressing rail in a tunnel is not a problem since the temperature ranges are not great. Note that the rail neutral temperature in tunnels will be significantly lower than for track exposed to sunlight. The range of temperatures experienced by rails in tunnels is also often higher on the low end since tunnels often stay warmer than the outdoors. ƒ The process of de-stressing and anchoring direct fixation track at grade is similar to work in tunnels except that the anchoring temperature will differ. 13.3.2.5 Drill and Epoxy Method of Direct Fixation Track Construction This article is not intended to be a procedure for the constructor to follow. It is meant to inform the designer of certain activities that should be followed. The constructor should present their procedure to the designer prior to construction commencement and the designer should be prepared to present “what-if” scenarios that could result in unacceptable quality. Those scenarios should always be resolved before any construction begins. 13.3.2.5.1 Surface Preparation Surface preparation of the base concrete slab for grout pads is generally as discussed in Article 13.3.2.4.7 with the exception that scabbling is limited to the footprints of the individual grout pads. 13.3.2.5.2 Scabble Concrete The invert concrete should be roughened and cleaned prior to grout placement. 13.3.2.5.3 Survey for Grout Pads Each individual grout pad must be identified and surveyed to a maximum tolerance of ⅛ inch. Identifying the footprint is one aspect. Identifying the elevation of all four corners is another aspect, especially for curved track on a gradient. Each pad will have a slightly different elevation and pitch in two planes. The superelevation must be laid out considering all four corners of each grout pad. The cant in the rail must also be surveyed if using zero canted fasteners. If canted fasteners are used, the grout pads opposite each other must be in the same plane. The formwork must be placed with all the parameters in mind. It would be advisable to have the constructor establish a detailed work plan to ensure that all the proper controls are in place. If the

Track Design Handbook for Light Rail Transit, Second Edition 13-44 pitch on the grout pad is incorrect, it will affect the cant of the rail and will generate an improper wheel-to-rail interface. 13.3.2.5.4 Pour Grout Pads to Rail Tolerances The grout pads must now be poured. If a grout pad is greater than 2 inches thick, it may require some wire mesh. If wire mesh is used, care must be taken so it does not interfere with the holes that must be drilled later. Grout should be mixed and placed according to manufacturers recommended practice. A steel trowel finish should be employed. A flat surface is extremely important since the fastener must not wobble on the rail seat. This would cause breaking or cracking of either the fastener or grout pad under dynamic loading. 13.3.2.5.5 Layout Hole Pattern The holes must now be drilled to accept the rail fastener anchor inserts or threaded rods. Drilling the holes could be done by core-drilling machines or pneumatic impact drills. Whichever method is used, care must be taken not to chip or break the grout pad. The hole pattern must be identified and the location for drilling marked. Care must be taken to drill holes perpendicular to the surface of the grout pad. Care must be taken on superelevated track. The holes will be plumb only when using canted fasteners on tangent track. All other conditions will require an angle other than plumb. Using zero cant fasteners will require a 40:1 batter inward from the vertical plane on tangent track. This geometry must be carefully thought out so problems do not occur later when the rail is installed. When laying out the inserts and measuring for gauge, the rail cant must be considered since track gauge is measured at the gauge line on the head of the rail, which will be at least 8 inches [240 mm] and sometimes even more above the plane of the grout pad. The size of the rail and the thickness of the rail fastener assembly must be known since the elevation of the gauge line of the rail will change the anchor insert layout geometry. 13.3.2.5.6 Drill Holes into Invert Using templates that are specially designed and fabricated to match the drilling equipment rather than the actual direct fixation rail fasteners is recommended. The templates can be designed to make certain the holes are at right angles to the grout pad surface and incorporate stops so the hole is cored to the correct depth. The depth of the hole will typically be greater than the cover on top of the underlying reinforcing steel. Drilling through the top layer of reinforcing steel may be permitted, but a structural analysis should be performed to ensure that the integrity of the invert is not compromised. Also, if reinforcing steel is encountered, another analysis with respect to potential stray current must be performed. Whatever grout or epoxy is used to install the anchor inserts, it should have good dielectric properties. The manufacturer of the grout or epoxy must be consulted for proper placement. Some require a smooth hole; some require the hole to have roughened edges. They all will require a clean dry hole prior to placing the epoxy or grout. Following proper procedures and quality control is essential. Extreme care must be taken when drilling holes in any guideway. Some elevated structures using segmental construction methods have transverse and longitudinal pretensioning and postensioning strands. Under no circumstances should these strands be compromised.

LRT Track Construction 13-45 13.3.2.5.7 Repair Grout Pads After holes are drilled into the grout pad and the invert, some pads may be damaged or broken. These must be repaired properly in order to maintain a proper bearing surface for the fastener. 13.3.2.5.8 Clean Holes Cleaning the holes is an important step in the process. If the holes are not properly prepared, separation may occur between the core-drilled hole and the epoxy surrounding the insert (or threaded rod) during the uplift cycle of dynamic forces imposed by the rolling vehicles. 13.3.2.5.9 Mix Epoxy and Install Anchor Inserts/Bolts Mixing the epoxy or grout will depend on the manufacturer chosen. A procedure should be submitted and approved prior to any placement. The anchor bolts or threaded rods must be held firmly in the correct orientation when the grout or epoxy is placed. The proper batter, alignment, and elevation are critical since this activity now sets the gauge, alignment, and surface of the finished track. In most cases, epoxy is placed into the hole and the insert or threaded rod is “stuck” into the hole. Using the proper amount of grout is important so as to fill the hole yet not overflow it. Overflow would cause an elevated area bearing on the bottom of the fastener and cause it to wobble. Alternatively, the inserts can be set first and then the grout pads poured. The top of insert sets the elevation for the pad, the inserts come out level with the pad, and the pad doesn’t have to be drilled. Not drilling the pad can spare it the impacts associated with drilling, which can cause cracking. However, since the grout pad would be thinner than the insert is tall, it is still necessary to mobilize core-drilling equipment. Other work sequences are also possible, and it’s very likely that grout pad type direct fixation track has been built in at least as many different ways as there have been contractors doing such work. 13.3.2.5.10 Attaching Fasteners to Grout Pads and Setting CWR The fasteners can now be placed onto the grout pad and the anchor bolts loosely engaged. Setting the CWR on top of the fastener is done as previously discussed for top-down methodology. The rail can be attached to the fastener and the fastener attached to the grout pad. Once this is accomplished, elevation, cross level, and rail cant must be verified. If adjusting is required, shims must be added or the grout must be ground to the correct elevation to bring the vertical profiles within tolerance. All measurements should be recorded for each fastener and a cut sheet produced. This can be easily verified if the information is tabulated in a spreadsheet and a graph is produced with limit lines. Once the out-of-tolerance locations are identified, corrective measures must take place. 13.3.2.5.11 Shim Rails to Elevation or Grinding the Grout Pads There are different materials that have been used for shimming purposes. Those are steel, plastic, high-density poly, stainless steel, and galvanized steel. When using a polymer base material, confirm that ultraviolet light will not break down the material. When using steel, ensure that this will not compromise the stray current protection. Note that slotted shims, while easier to install, may work out of position under dynamic loading and time. A locking mechanism may be advisable when using slotted shims. In some cases, it may be necessary to grind the grout pad to achieve the tolerances for elevation, cant, and cross level.

Track Design Handbook for Light Rail Transit, Second Edition 13-46 Shimming and re-canting can change the horizontal alignment and track gauge. For this reason, it is advisable to correct the vertical parameters first. Only once the vertical corrective measures have been finished should final horizontal adjustments be made. 13.3.2.5.12 Line and Gauge Rails The line rail is always set first to the proper alignment using centerline of track indicators or a surveyor’s transit. There is only so much adjustment in the slots of the fasteners, and one misplaced pair of inserts could affect several fasteners on either side. If there is not enough room in the slot to set the alignment, the inserts or threaded rods must be cored out and a new set epoxied in. When doing this correction, always maintain and account for the shims that may have been placed in the previous step. Once the line rail is brought to proper alignment, the other rail can be set to proper gauge. If there is not enough adjustment remaining in the fastener body, they must be drilled out also and reset. 13.3.2.5.13 Thermal Adjustment After all aligning and gauging is completed and all bolts torqued, the thermal adjusting of the CWR can take place as previously discussed. 13.3.2.6 Embedding Inserts into Precast Segments There have been some attempts to embed inserts into the guideway in order to fasten the direct fixation fasteners without either plinths or grout pads. The results have varied widely from reasonably good to disastrous. In the absence of extremely strict quality control, these methods can result in incorrect cant on the rail and bad horizontal geometry even after using up all of the adjustment capacity on the rail fasteners. In order to produce a safe reliable system, the gauge, rail cant, vertical alignment, horizontal alignment, and superelevation must be set within very tight tolerances. If the owner inherits a poorly constructed system, the cost of maintenance will be higher and the owner’s performance, as perceived by the riding public, will be inferior. The advantages of construction without plinths or grout pads include the following: • If done correctly, it can save track construction time since many of the tedious procedures described above for both plinth and grout pad direct fixation track can be omitted. However, significant additional time is necessary at the casting yard to be certain the anchor inserts are in precisely the correct locations. • The structural dead load will be somewhat less due to the omission of the plinths. Factors weighing against this type of construction include the following: • Absolute cooperation and extremely close coordination is required between the contractor(s) responsible for erection of the aerial structures and the contractor responsible for the track. • The structural engineers cannot control the camber of the finished bridge deck to the extremely tight tolerances specified for track construction. The result may be far more shims beneath the rail fasteners than might be prudent. This could result in high moment loadings of the rail fastener anchor bolts. The anchor bolts might need to be provided in

LRT Track Construction 13-47 a variety of lengths so as to provide a reasonably consistent amount of thread engagement. Verification that the appropriate length bolt has been used at a particular location would be very difficult and tedious. • Reduced clearance between the base of the rail and the invert. If this distance is less than about 2 inches [5 cm], debris such as leaves, blowing newspapers, and other paper trash may get caught under the rail. Those items in turn will catch and hold smaller debris. In addition to blocking drainage, this could ground the track system, causing problems with the train control system as well as providing a path for stray current. • Any discrepancies in the as-cast positions of the inserts will not be apparent until the rails are set and the contractor is attempting to set final alignment and gauge. Any corrections for horizontal alignment may require drilling holes in the post-tensioned segments. This will carry a very high risk number. Prior to any decision to cast inserts into the segments, it would be prudent to do a full and complete risk analysis to ensure that risk is mitigated to a level acceptable to all parties—the constructors, the designers, and the owner. If this method is chosen, it is essential to think everything through in extreme detail. One mistake in this methodology can produce an inferior product that will fail prematurely. 13.3.2.7 Top-Down Methodology Advantages Since “top down” is the preferred method of most track constructors, this discussion will describe the principal advantages of this form of construction. If the track system is built properly, an owner can have a system that will be safe and reliable and will last for a very long time. All of the items are achievable with good quality control and an experienced track constructor. The following advantages are noted: • Since all metal components are placed prior to the placement of the concrete, visual inspection will generally ensure that proper isolation (or bonding) has been achieved. • Since the rail is set first, any type of fastener—flat or canted—can be used to achieve any desired amount of rail cant. This can include zones of transitional rail cant such as from the standard 40:1 up to a 20:1 for improved curving or down to a zero cant in a turnout. • It is possible to use rail fasteners that do not incorporate lateral adjustment capability since all adjustments can be made in the jigs prior to concrete placement. This reduces the cost of the rail fasteners themselves. Several owners eschew lateral adjustment capability in their rail fasteners on the grounds that they never need it for maintenance and including it merely becomes an excuse for the constructor to be lax on quality. • No relining, re-gauging or re-setting elevation. Once the rail has been set the first time, there is no need to set these parameters again assuming the constructor took the proper precautions and used the proper templates. • Since the rail is set first, the proper cant is guaranteed. • Rebar can be inspected prior to placement of concrete, and, since there should be no drilling into the concrete, the integrity of the reinforcing steel is maintained.

Track Design Handbook for Light Rail Transit, Second Edition 13-48 • It is always more cost-effective to do it right the first time. Re-work is costly and will affect both the quality of the track structure and the money aspect to achieve the tolerances. • Top-down methodology creates the best end product and one that is not patched and scarred because of re-work. It is absolutely possible to produce a quality project that will last for decades. It is the designers’ collective responsibility to educate themselves on the likely construction methods and particularly to research the problems that have happened on previous projects due to ill-conceived construction methods, poor quality of work, and poor workmanship. An impeccable quality control program will be the guide to success. It must be adhered to and personnel held accountable for both success and failure. 13.3.2.8 Lessons Learned the Hard Way There have been some very important lessons learned during both the design and construction phases of light rail systems. It can be a valuable tool to understand during the design phase of a project. We have an obligation to learn from our mistakes and to share them with the industry. The ultimate user of these systems must be safe, and the designer and constructor have the responsibility to deliver this to the owner. Some of these lessons learned include the following: • Getting the rail cant wrong: If the constructor has not set the rail cant properly, it will make things very difficult for the Maintainers of the system. It will cause poor wheel/rail interaction, which leads to poor ride quality, truck hunting, accelerated wear on both the wheels and rail and possibly even rail defects. Some properties have ground the rail head to match the 40:1 cant that should have been produced by the rail fastening. However, this causes the force vector (L/V) to move outside the web of the rail, causing unnecessary forces in the head-to-web area of the rail section. Using any method other than “top down” will have a much greater risk of causing this poor relationship between wheel and rail. • Voids under the plates: Small voids or air pockets are common to placing concrete under a flat surface. However, as long as these are not large voids due to improper concrete consolidation, they will not affect the integrity of the structure and can be easily patched. They can be minimized by use of a concrete mix design with a low water/cement ratio and through proper concrete vibration methods. Using the concrete vibrator correctly will greatly reduce the volume of trapped air. • Crooked inserts: Inserts that are not perpendicular to the bottom plate of the fastener can be at risk to shear since the lateral forces are concentrated on a very small area. Crooked inserts are caused by poor quality control when performing a checklist prior to placing concrete. Each insert should be touched to ensure it is snug to the base of the steel shim. Just because it looks vertical does not mean it will not be moved by the flowing concrete. • Rail expansion during concrete pours: If the rail length changes before the concrete has taken an initial set, there is a good chance the rail will drag the rail fasteners and the anchor inserts through the molten concrete. Understanding the forces that can occur due to temperature change will allow for proper procedures that can substantially reduce the

LRT Track Construction 13-49 risk. Rail temperatures rise dramatically during the morning and then level off for many hours before finally decreasing after sunset. Either a consistently sunny day or a consistently cloudy day is perfect for concrete placement. Placing concrete at night when temperatures are relatively constant can also offer relief from this factor. Using lengths of rail no longer than 300 feet [91 meters] can reduce the risk. Using temporary rail clips that exert a very low toe load will mitigate the risk. Some temporary clips include a thumbscrew arrangement so the clamping force can easily be reduced as soon as the concrete has taken an initial set. Good planning and understanding of the forces involved will greatly reduce this risk factor. Identifying rail temperature ranges for concrete placement will reduce the risk. Performing a rail temperature analysis to determine the best time to place concrete will save many problems later. It is a good practice for the engineer to consult with others that have performed, designed, and maintained direct fixation track structures. They will gain valuable information in order to make intelligent decisions based on lessons learned. Each project has a set of circumstances that may be slightly different than another project, but in general they have many similarities in means and methods as well as lessons learned. 13.3.3 Construction Issues for Embedded Track The purpose of this discussion is to offer procedures for the construction of the embedded trackform. There have been many methods attempted, and some have resulted in failures. Unfortunately, the failures may not be recognized until years after their construction. This article will describe not only some proven methods but also some of the less advantageous procedures that may require a higher level of track maintenance. 13.3.3.1 Construction Concept Understanding the different methods of construction may help the designer when choices must be made with respect to material, location, and geometry. Different methodologies offer varied advantages and disadvantages. The same philosophy previously recommended for direct fixation track will apply here with the exception that the concrete is placed to the top of the rail, fully encasing the rail in concrete. This presents some challenging problems such as how to deal with noise, vibration, and electrical isolation, as well as a proper running surface for motor vehicles. 13.3.3.1.1 Top Down This is a widely used methodology and has been accepted as “best practice” and hence become an industry standard. Placing concrete after the rail has been set and tested for electrical isolation is the preferred method. With proper quality control during construction, this process results in a track system that should last for decades with minimal maintenance. 13.3.3.1.2 Bottom Up Placing the concrete first and only then adding track components until the top of rail is achieved relies totally on placing concrete to within the tolerances required of the track. It is far more difficult to place concrete within ⅛ inch [3 mm] than it is to set the rail to that tolerance. When designing these systems, the construction methodology must be taken into consideration.

Track Design Handbook for Light Rail Transit, Second Edition 13-50 13.3.3.1.3 Drill and Epoxy When drilling holes in concrete and placing inserts or threaded rods, it must also be performed within the track tolerances. In some cases, these tolerances have been set to 1/16 inch [1.5 mm]; however, in most cases the tolerances are ⅛ inch [3 mm] . 13.3.3.1.4 Slab Concept This concept places a flat concrete slab and then builds the track on top of that. This offers the constructor the option to use either a top-down or bottom-up method. 13.3.3.1.5 Tub Concept If this method is chosen, the subgrade must be placed within the tolerances of the track when precast tub sections are used. This is another form of bottom up. Extra care must be taken when preparing the subsurface. The subsurface must be well compacted so no settlement occurs later, during rail installations. 13.3.3.1.6 Trough Concept This concept places the concrete first, leaving two “slots” or troughs in the slab for the rails to be set. In some cases, the threaded rods are installed during concrete placement. This requires extreme care when choosing the formwork to hold the rods in place during placement of the concrete. The formwork for the troughs must be well supported in order to accept the pressure of the concrete, especially uplifting forces that might cause the formwork to “float.” The elevation of the concrete pavement will need to be placed very close to the tolerances specified for the track, which will generally be much tighter than the concrete contractor is used to. The geometry must be well thought out when mixing roadway with railway, and extra care must be taken when placing concrete on a grade where the track curves within the gradient. Roadway surfaces are measured perpendicular to the alignment of the roadway, and track elevations are measured perpendicular to the rails. If the track profile and the pavement grades have not been very carefully coordinated, this can result in a rail appreciably lower or higher than the adjacent concrete surface. If the rail is left above or below the roadway surface, serious accidents can occur (and have occurred) involving roadway vehicles, especially if the roadway and railway alignments are horizontally skewed to each other. 13.3.3.2 Preparatory Work Because embedded track construction generally occurs within public rights-of-way and on constrained worksites, it is extremely important to “plan the work and work the plan.” The following activities can help a project “get off on the right foot.” Preplanning and communication will only help the execution. Many of these categories can be “show stoppers” to the construction, which will only lead to claims, change orders, and possible litigation. Possible problems should be identified and, to the degree possible, mitigated prior to construction. Preparatory factors that should be investigated include the following: • Providing a site plan showing utilities and other pertinent data. This will build upon the construction contract drawings, adding information that is particularly relevant from a constructor’s point of view and that is reflective of the constructor’s means and methods.

LRT Track Construction 13-51 • Determining accessibility, that is, for each discrete activity, how the constructors will get materials, equipment, and labor to and from the worksite. • Identifying the volume of vehicular traffic for the purpose of road closures and detours. • Identifying pedestrian traffic paths and volume and determining how to prevent harm to the general public. • Conducting a pre-inspection of the area to account for and mitigate any potential problems. • Performing a baseline stray current report prior to any construction activity to at least verify that levels are acceptable before construction begins. • Investigating the geometry of the roadway surface and superimposing the geometry of the track to identify locations where the two may not be synchronized. Locations of deliberate reverse superelevation should be clearly identified. • Confirming that hazardous material, permitting, and detours have been thought out. • Developing and reviewing plans and procedures for disposal of excavated material. • Considering fire and emergency response during construction. • Recognizing and planning around “Dig Safe” and other early warning notifications prior to construction activities. • Performing an overall risk analysis and survey. • Performing regular document control, scheduling, and planning. Proper and timely audits should be the norm to ensure correct controls are in place and being performed. This is a minimal checklist, and there may be other items specific to the project that need to be added. Thinking through the project in great detail while playing the “what-if” game can save countless hours of frustration and discontent during the course of any project. 13.3.3.3 General Overview of Construction This article explores the construction activities that will be required to build a safe and reliable system. The intent of this article is to offer the designer some “food for thought” while designing the system. If there are different choices for design, offering one that is easier and more cost- effective may be the owner’s preference. Understanding the construction process can only help in the design decision-making process. 13.3.3.3.1 Excavation and Drainage Once all the preparatory work is completed and any high-risk items mitigated, the construction phase can begin. It starts with a saw cut in the existing pavement and excavating to the correct depth. A drainage system would be installed at this time and is generally in the form of an underdrain consisting of perforated pipes with the holes facing down surrounded by crushed

Track Design Handbook for Light Rail Transit, Second Edition 13-52 stone and wrapped in a filter fabric. Cleanouts are typically placed at strategic locations, mainly in the bottom of vertical curves. 13.3.3.3.2 Compaction This should never be overlooked. The subgrade becomes the foundation for the highway and railway. Many properties will use an asphalt underlayment of 6 to 8 inches [15 to 20 cm] thick to guarantee 100% compaction. Evaluating the additional cost compared to the potential problems is essential. In well-compacted soils, this may not be necessary. Where organic material or soft soil is encountered, this may be the norm. It may be necessary to overexcavate to remove this unwanted material. If this is the case, new fill will be needed. This fill material should be suitable and compatible with the adjacent soils so as not to permit uneven or abrupt settlement. The engineer must realize that this activity must be scrutinized and ensure that good quality controls are implemented. 13.3.3.3.3 Installing Underground Electrical Conduits Installing the electrical conduits can be very challenging since in some cases the signal and other electrical systems may not yet be fully designed. Adding a few extra conduits in strategic areas can save countless hours of chopping concrete and destroying the integrity of the embedded track. The signal system may need impedance bonds, and block outs in the concrete may be necessary. Negative return systems will need wires also as well as the grounding system, depending on whether collection or isolation is chosen. Engaging the electrical constructor during this activity is very important. Proper coordination among all parties involved should be standard procedure. 13.3.3.3.4 CWR Much like with direct fixation track, decisions must be made as to how the CWR will be handled and placed. Unlike the direct fixation method where the rail is exposed, the actual rail must be used in the construction since it will be fully encased in concrete. String lengths may be governed by the amount and length of road closures that will be permitted. Intersections are always a challenge and must be well thought out. Will the intersection be available for a full closure or must it be completed one half at a time? Will temporary roadways be required or detours implemented? These and other questions must be answered to determine the proper lengths of CWR to be used. 13.3.3.3.5 Construction in the Urban Environment Working in an urban street environment is not the same as working in a fenced in building site or a rural area. Extra care must be taken to protect the general public. The general public typically understands very little about the construction process and cannot be depended on to watch out for its own safety. Detouring people and vehicles is the safest approach. If appropriate measures have been taken to either exclude the general public from the construction zone or to carefully manage and control its interaction with the construction, it reduces the chances of “incidents” and risk analysis numbers are low. Fences and barricades can prevent exposure to dangerous activities and material. Rerouting sidewalks will reduce the possibility of a pedestrian wandering into the construction site and getting hurt. In many cases, management of pedestrians is more difficult than motor vehicles, particularly in cities where “jaywalking” is common behavior.

LRT Track Construction 13-53 13.3.3.3.6 Safety Safety is the number one concern of all parties involved including the general public. A professional, well-trained safety engineer should be employed and always invited to meetings offering a perspective from a safety point of view. 13.3.3.3.7 Welding Rail When welding rails into strings, it is necessary to make some decisions as was done for other trackforms. In most cases, it may be advisable to simply weld long strings and cut from each string the lengths that are required. Close controls are required to ensure that each piece of each string has a designated location and the location is documented along with the heat numbers associated with that piece. Care must also be taken to confirm that head-hardened rail is placed properly and according to the specifications. It is common practice to install head-hardened rail in sharper curves since this type of rail can offer 40% more life. The placement of field welds is critical for this form of track. Criteria are included in the specification on where field welds should not be placed, such as at road crossings, within 15 feet [4.5 meters] of another field weld in the same rail, or within 5 feet [1.5 meters] of another weld in an opposite rail. These criteria would be identified by the designer or the owner. 13.3.3.3.8 Setting the Track with Isolation Setting both rails to the proper geometry is similar to direct fixation track construction methods; however, supporting fixtures, such as I beams or plastic ties, can be encased in the concrete and used as sacrificial elements to hold both rails in the proper geometry. Applying a rubber boot or other isolating membrane is critical to the longevity of the system. When using a rubber boot or other method, it must be checked for imperfections in order to confirm that the rail is isolated. This can be accomplished by using a megger type system that discharges an electrical current that is continually seeking ground. If there is a pin hole in the boot, the testing system will create a spark indicating that the membrane has been compromised. This hole must be properly patched per manufacturer-recommended practices. Ignoring this final check prior to placing concrete could cause serious repercussions later and will most assuredly produce a failure mode when track-to-earth resistance testing is performed. This isolation system should also serve as a form of noise and vibration protection. Concrete placed directly in contact with the rail will fail in a short period of time since concrete is not designed to withstand the vibration imposed by trains. It would be in the engineers’ best interest to explore all the possibilities and educate themselves about lessons learned with respect to this topic. The engineer always has the ability to write a performance specification instead of identifying specific products. This is a decision that the owner and the designer make together. 13.3.3.3.9 Thermal Adjustment of Embedded Rail—Required? In ordinary ballasted track, it is essential to adjust the rail to a zero thermal stress temperature so as to minimize the chances of track buckling during hot weather and pull aparts during cold weather. Track buckling is extremely unlikely to occur in embedded track because the mass of the surrounding concrete pavement will both constrain the rail from lateral movement and act as a heat sink, keeping the rail temperature well below that which might be experienced in an open trackform. Doubtless because of these factors, experience has shown that it is unnecessary to heat embedded rail during laying. Instead, it can simply be encased in the concrete at reasonable temperatures. The rail will assume the temperature of the concrete as the latter is

Track Design Handbook for Light Rail Transit, Second Edition 13-54 placed and cures. Notably, the concrete pour itself will have temperature range restrictions (typically 40° to 95° F / 4° to 35° C) based on Portland Cement Association recommendations. In addition, for embedded track that uses rail boot, slippage between the boot and the rail will generally relieve the small amount of thermal stress that can occur as the rail matches the temperature of the curing concrete. Hence, it is unnecessary to de-stress embedded rail so long as it is in a zero-stress condition at the time of the concrete pour. The greater temperature-related issue in top-down embedded track construction is keeping the skeletonized track in alignment prior to and during the concrete pour. As is the case with top- down construction of direct fixation track, the position of the rails should be closely monitored during the pour. 13.3.3.3.10 Placing Initial Concrete Only up to Base of Rail—or Not Once the rail has been set to the proper grade, line, and gauge, it is time to pour the concrete. A decision must be made as to whether to place the concrete to the top of rail in one lift (single-pour method) or stop at the base of rail and make a second concrete pour on top of that (two-pour method). If a topping other than concrete, such as brick or blockstone pavers is preferred, the two-pour method is required. In some instances, the top of the slab will be colored concrete stamped with a decorative design. This would require a two-pour methodology. Other issues to consider include the following: • When placing a large depth of concrete, it is awkward for workers stepping in the wet concrete since the risk of a twisted ankle or other injury is higher. • If the two-pour method is chosen, it gives one last opportunity to verify total electrical isolation of the rail when repairs can still be made without chopping concrete. • A two-pour system introduces a cold joint between layers of concrete, so the first pour must remain roughened and no curing compound should be used. The decision of whether to use a single- and two-pour method is often best left to the constructor, since some are better than others at concrete placement. Whichever method is chosen, the most important aspect is again good quality control and producing a checklist as verification. 13.3.3.4 Lessons Learned the Hard Way There have been some very important lessons learned during both the design and construction phases of light rail systems. It can be a valuable tool to understand during the design phase of a project. We have an obligation to learn from our mistakes and to share them with the industry. The ultimate user of these systems must be safe, and the designer and constructor have the responsibility to deliver this to the owner. The bullet points below are some lessons learned from many constructors and designers: • Placing concrete below the top of rail: When constructing embedded track that will be shared with rubber-tired vehicles, it is imperative that the top of the rail remain even with the top of the concrete except that an area within a short distance on the field side may be left depressed ⅛ to ¼ inch [3 to 6 mm] to account for hollow wheels and prevent the wheel from contacting the concrete. On one project, a section of rail that was skewed to the path of motor vehicles was sticking out above the concrete by almost ½ inch [13 mm]. This condition was a significant contributing factor to a fatal motorcycle accident.

LRT Track Construction 13-55 • Not testing the boot or isolation method: If the boot is not tested for holidays prior to placing concrete, the track-to-earth resistance test may fail. If this test fails, it is quite an ordeal to locate the problem. Once the problem is located, concrete must be removed and the insulating membrane repaired. Then new concrete must be placed to repair the hole. This vertical joint in the concrete is very likely to become a maintenance headache due to freeze/thaw cycles or water migration. • Not testing rebar continuity: The rebar mats should be tested for continuity if the collection method is chosen. If the mats are not continuous or the return path is not properly connected in the substation, the current will stray and begin damaging the steel components at a rate of 20 pounds [9 kg] per ampere per year, according to Faraday’s law. If concentrated in a few locations, this corrosion can be very dramatic over a short period of time and may jeopardize the entire structure. Therefore, be cautious when choosing the collection method. • Not monitoring rebar and concrete placement: When a crew places concrete, it may be thought of as organized chaos. Using checklists before, during, and after concrete placement can save money, time, and embarrassment. However, concrete pours for embedded track are distinctly different from ordinary roadway work. The typical roadway concrete pavement crew is used to working within a tolerance of ¼ to ½ inch [6 to 12 mm] and believe they are doing really well if they meet the lower end of that scale. However, the completed track usually must be within ⅛ inch [3 mm] of the specified alignment. Communicating this tight tolerance requirement to both the concrete superintendent and the actual concrete crew is critical since it is the actions of the latter that will possibly knock the track out of alignment. It is highly desirable to have a survey corps present to check and recheck track alignment immediately before, during, and after the concrete pour. The trackwork constructor should also have at least a supervisor present during the pour, and it should be understood in advance that any dislocation of the track will require a suspension of the pour until after the misalignment has been corrected. If an alignment defect is not discovered until after the concrete has set up, it will need to be chopped out to correct the defect. The demolition of the green concrete is virtually certain to damage not only the embedded rebar but also the rail boot. The cost of reconstruction would be substantial, making it highly desirable to “get it right the first time.” The location of the rebar must be monitored also. If the concrete flow moves the rebar cage, it may damage the rail boot and result in a “hot spot” with a path for stray current to ground. • Inexperience: A good track constructor makes track construction look very easy. It is tempting for the novice contractor to tackle these projects without understanding what is really involved. (This caveat applies to designers as well.) Inexperience can only be overcome by experience. Many public agencies are legally required to award contracts solely on low price; however, if it is permissible, owners should strongly consider pre- qualifying and shortlisting contractors prior to asking for bids or issuing a request for proposals. The experienced constructor who costs a little more will usually result in the best value to the owner. The end user of the light rail system depends upon and expects

Track Design Handbook for Light Rail Transit, Second Edition 13-56 a safe and quality product for themselves and their families to use. It is the responsibility of everyone on the project to do their best to achieve this. • Not following a QA/QC Program: This has been mentioned throughout this chapter and has been emphasized in a very strong way. An impeccable QA/QC program should be a mandatory requirement. While having a complete and auditable paper trail is one aspect of a comprehensive quality program, actually following the procedures is the far more important part. Audits are a check to ensure proper implementation. Qualified people that have support from the highest authority are the secret to success. Build a safe, reliable system that everyone can enjoy for generations to come.

Next: Chapter 14 - LRT Track and Trackway Maintenance »
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TRB’s Transit Cooperative Research Program (TCRP) Report 155: Track Design Handbook for Light Rail Transit, Second Edition provides guidelines and descriptions for the design of various common types of light rail transit (LRT) track.

The track structure types include ballasted track, direct fixation (“ballastless”) track, and embedded track.

The report considers the characteristics and interfaces of vehicle wheels and rail, tracks and wheel gauges, rail sections, alignments, speeds, and track moduli.

The report includes chapters on vehicles, alignment, track structures, track components, special track work, aerial structures/bridges, corrosion control, noise and vibration, signals, traction power, and the integration of LRT track into urban streets.

A PowerPoint presentation describing the entire project is available online.

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