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14-i Chapter 14âLRT Track and Trackway Maintenance Table of Contents 14.1Â PURPOSE 14-1Â 14.2Â TRACKWORK STANDARDS 14-1Â 14.2.1Â Track Construction Standards 14-1Â 14.2.2Â Track Maintenance Standards 14-1Â 14.2.3Â Track Safety Standards 14-2Â 14.3Â ACCEPTANCE 14-3Â 14.4Â WORKING SAFELY ON THE RAILWAY 14-3Â 14.4.1Â Track Protection 14-4Â 14.4.2Â Flag Persons 14-4Â 14.4.3Â FRA 214 Regulations (If Applicable) 14-4Â 14.4.4Â Risk Analysis 14-5Â 14.4.5Â Preparatory Work 14-5Â 14.4.6Â Profile of a Safe Person 14-5Â 14.5Â INSPECTING THE SYSTEM 14-5Â 14.5.1Â How Often? 14-5Â 14.5.2Â Priority Lists 14-6Â 14.5.3Â Qualifications 14-6Â 14.6Â MAINTENANCE ACTIVITIES 14-6Â 14.6.1Â On-Track Maintenance-of-Way Equipment 14-6Â 14.6.2Â Maintenance Issues Common to All Trackforms 14-7Â 184.108.40.206Â Insulated Joints 14-7Â 220.127.116.11Â Rail Corrugation and Rail Grinding 14-7Â 18.104.22.168.1Â Rail Corrugations 14-7Â 22.214.171.124.2Â Rail Grindingâthe Basics 14-8Â 126.96.36.199.3Â Rail Grinding Frequency 14-8Â 188.8.131.52.4Â Specifying a Rail Grinding Program 14-9Â 184.108.40.206.5Â Special Challenges for Transit Rail Grinding 14-11Â 220.127.116.11Â Repair Welding and Grinding of Switches and Frogs 14-12Â 18.104.22.168Â Emergency Repairs 14-12Â 22.214.171.124Â Maintenance Documentation 14-12Â 126.96.36.199.1Â The Federal Railroad Administration 14-13Â 188.8.131.52.2Â The American Public Transportation Association 14-13Â 184.108.40.206.3Â The Federal Transit Administration 14-13Â 14.6.3Â Embedded Track Maintenance Requirements 14-13Â 220.127.116.11Â Cleaning the Flangeways 14-13Â 18.104.22.168Â Repair Top Surface 14-14Â 22.214.171.124Â Spotting Stray Current 14-14Â
Track Design Handbook for Light Rail Transit, Second Edition 14-ii 126.96.36.199Â Snow Removal 14-14Â 188.8.131.52Â Repair Broken Rail 14-14Â 184.108.40.206Â Replace Worn-Out Rail 14-15Â 220.127.116.11Â Replacement of Parts in Embedded Specialwork 14-15Â 18.104.22.168Â Rail Grinding in Embedded Track 14-15Â 14.6.4Â Direct Fixation Track Maintenance Activities 14-16Â 22.214.171.124Â Tighten Bolts 14-16Â 126.96.36.199Â Rail Clip Maintenance 14-16Â 188.8.131.52Â Housekeeping 14-17Â 184.108.40.206Â Regauging Track for Rail Wear 14-17Â 220.127.116.11Â Repair Cracked and Spalling Concrete 14-18Â 18.104.22.168Â Repair Caulking 14-18Â 22.214.171.124Â Repair of Broken Rail 14-18Â 126.96.36.199Â Replacing Rail Fasteners 14-18Â 188.8.131.52Â Rail Fastener Anchor Insert Replacement 14-19Â 184.108.40.206Â Replace Continuous Welded Rail 14-19Â 220.127.116.11Â Replace Parts in Special Trackwork 14-20Â 14.6.5Â Ballasted Track Maintenance Activities 14-20Â 18.104.22.168Â Ballast Maintenance 14-20Â 22.214.171.124Â Surface Track 14-20Â 126.96.36.199Â Repair Deflector Ramps at Crossings 14-21Â 188.8.131.52Â Replace Pads and Insulators on Cross Ties 14-21Â 184.108.40.206Â Replace Cross Ties (Timber and Concrete) 14-21Â 220.127.116.11Â Vegetation Control 14-21Â 18.104.22.168Â Drainage Maintenance 14-22Â 22.214.171.124Â Yard Cleaning 14-22Â
14-1 CHAPTER 14âLRT TRACK AND TRACKWAY MAINTENANCE 14.1 PURPOSE The designer should understand that once the system is designed, built, and turned over to the owner, it will need to be maintained. All too often, the focus of the designers and constructors is only on building the project with insufficient attention to the interests of the maintainers. In many cases, it has been assumed by the owner that maintenance will not be required. The fallacy of such assumptions is usually not apparent until conditions have deteriorated to a level where corrective measures are difficult and expensive and cause significant inconvenience for all parties, including the system users. If a system of periodic inspections and preventative maintenance is in place from the beginning, all properly designed and constructed LRT trackforms should last for decades without requiring significant reconstruction. This is largely because of the small axle loads of rail transit vehicles. The purpose of this chapter is to offer some recommendations for maintaining all trackforms so that the designer has a basic understanding of the requirements. Much of maintenance is generic to all trackforms, but some require more specific focus to achieve success. FRA, APTA, and the FTA have developed some general criteria that can be useful, but it is the responsibility of each owner to develop a maintenance program specific to its system. It is important to include the ownerâs maintenance-of-way (often abbreviated as either M/W or MOW) department in design decisions that may affect maintenance after construction. The maintenance-of-way department may have existing standards and methods in place that can be directly applied to the new construction whereas new methods may not be applicable to their existing infrastructure. Keeping things simple for the maintainers goes a long way toward ensuring that the system will be maintained and remain in state of good repair. In the case of a new LRT system that does not yet have an in-house maintenance organization, the designer may be in the best position to initiate a comprehensive plan for inspection and maintenance of LRT track. 14.2 TRACKWORK STANDARDS The designer must set certain tolerances for the construction entity to build the project. These standards are completely different than either maintenance standards or safety standards. 14.2.1 Track Construction Standards Construction standards are tolerances that must be met during the building portion of the LRT system. See Chapters 4 and 13 for discussions on construction tolerances. Construction tolerances typically reflect the use of new, unworn materials and typically cannot be achieved once the system is in operation and the components have begun to wear. 14.2.2 Track Maintenance Standards Maintenance standards are for maintainers to use and not for new construction. They represent desirable minimum limits so that satisfactory operations can continue. Maintenance standards, like the safety standards discussed in the next article, are typically established for certain speeds
Track Design Handbook for Light Rail Transit, Second Edition 14-2 and classes of track. These standards will be unique to each transit property based on its needs and objectives. Inherent in any maintenance standard is an expectation that a certain amount of deterioration will occur before the next cycle of maintenance but that ride quality will not be impaired to the degree that corrective action becomes mandatory. Track maintenance standards and related requirements are typically codified in manuals and other documents developed specifically for each railway. These procedures will address many conditions and may include the following: â¢ Track charts of the property identifying speeds, alignment, curve radius, gauge, and cross level â¢ Criteria for drainage and vegetation control â¢ Maximum allowable dimensions for track gauge and alignment, both vertical and horizontal â¢ Criteria for maximum acceptable ballast and cross tie deterioration â¢ A CWR plan (sometimes called âtrack buckling countermeasuresâ) â¢ Criteria for inspection and maintenance of plinth concrete and embedded track slabs â¢ Criteria for inspection and maintenance of turnouts â¢ Criteria inspection and maintenance of other track appurtenances such as bumping posts, rail expansion joints, etc. â¢ Criteria concerning resuming operation after a severe weather event such as high water â¢ Torque limitations for anchor bolts and other threaded fasteners â¢ Inspection frequency and record-keeping requirements The above is only a partial list, and reference should be made to standards and recommended practices in the industry. Many properties will assign color codes to various criteria to establish degree of severity and actions to be taken. 14.2.3 Track Safety Standards Track safety standards are criteria that signify absolute limits for safe operation at various speeds. If the track structure deteriorates beyond these safety standards, then immediate action must be taken. That action might be â¢ Correction of the defect so as to bring the track into compliance. â¢ Reduction of train speed to a level consistent with the conditions that exist. â¢ Removal of the track from service until such time as the condition has been corrected. Typically, at least two of the actions noted above will be required in response to any individual class defect. For example, if the defect cannot be corrected immediately upon detection, a speed restriction would be imposed (first action) until a crew can be mobilized to correct the problem (second action). Obviously, the preferred circumstance would be that the track never deteriorates to a level where safety limits become a consideration because maintenance standards have been adhered to.
LRT Track and Trackway Maintenance 14-3 While the Federal Railroad Administration has a comprehensive set of track safety standards (see 49CFR213) that are a useful reference, they technically do not apply to urban rail transit systems that are not connected to the general railroad system. Moreover, there is much in the FRA Track Safety Standards that could be misleading for a system that does not employ AAR wheel profiles and wheel gauges. APTA published safety standards for the transit industry in 2007. They are great resources for an agency to develop both maintenance standards and safety standards but are necessarily generic and therefore must be adapted to the specific conditions of each rail transit line. As of 2010, the FRA has been charged by Congress to develop safety standards for transit systems that are not connected to the general railway system. This will ultimately result in fines for noncompliance. 14.3 ACCEPTANCE Once a track is accepted by the owner, their maintenance organization (which might be either an internal department or an outside contractor) will take over responsibility for the track from the constructor. The designer should understand what is important to the owner before the maintenance organization assumes responsibility. The following are some of the minimum requirements prior to transferring responsibility from the constructor to the maintainer: â¢ Documentationâthe proper documents will need to be turned over to the owner upon completion of the project. These documents should have been gathered throughout the course of construction according to the QA/QC program. These documents are an integral part of the development of standards for maintenance. Not only will this pertain to the track but also to systems, vehicles, structures, and other pertinent parts that make the whole. It is common for maintenance manuals to be developed by the builder and turned over to the owner upon completion. Sometimes these documents are not produced because of the sense of urgency to start revenue service. Once revenue service begins, many items are forgotten, and sometimes the forgotten items include maintenance manuals. If proper audits and good quality control were maintained during the construction phase, this should not be the case. â¢ Final Inspectionâthe owner should take part in the final inspection and acceptance. Only after any discrepancies have been resolved should revenue service begin and the maintenance group take over. The maintenance group should not be left with the task of completing punch list items. â¢ Satisfying NCRs (Non-Conformance Reports)âany NCRs that were generated during the course of the construction must be signed off on and accepted by the engineer prior to acceptance and release of any retention money to the contractor. Refer to Chapter 13 for more detail about NCRs. A good QC program will track NCR disposition and put up red flags if not satisfied during a reasonable amount of time. 14.4 WORKING SAFELY ON THE RAILWAY Safety is more than just important, it is essential. Safety must both precede and be concurrent with any actual maintenance work. Readers who are familiar with railroad engineering and maintenance organizations know how they invariably start any activity, even a meeting within an
Track Design Handbook for Light Rail Transit, Second Edition 14-4 office, with a safety briefing. The purpose of the briefing is to make certain that everybody understands the activity to be performed, the procedures for doing it in a safe and approved manner, and, in the event of an emergency, what to do to minimize injury or other harm. Following that example, this discussion on rail transit system maintenance will be prefaced with a discussion of safety. Maintaining the light rail transit line is distinctly different from building it because many maintenance activities must be conducted during train operations. The approach toward safety therefore needs to be different as well. Roadway worker protection has been an important topic in the industry with recent changes and modifications. Understanding how the railway works and how to be safe when working on the railway are paramount to the safety of every person. 14.4.1 Track Protection The track designer must understand how people will maintain the track and the personal safety procedures they will follow and then consider whether it may be necessary to include infrastructure or systems features that will facilitate their safety. Protection of on-track workers from approaching trains can take many forms depending on the configuration of the work zone, the speed of approaching trains, and the type of work being done. At one extreme is implementing temporary âtrip stopsâ to absolutely stop a train if it enters a work zone. More common is a simple line-of-sight procedure using flaggers who warn of an approaching train, somewhat similar to how highway crews are protected during maintenance work. Determining which protection is appropriate for various types of work is the decision of the owner and will typically be codified in written procedures. Issues to be addressed by the procedures include questions such as whether the maintainers will be permitted to work on live track, and, if so, how they will be protected from being hit by a train. Training of the workers in the proper procedures to follow and the possible dire consequences of not abiding by the rules is paramount. 14.4.2 Flag Persons Persons that observe train movement and are in contact with the dispatcher are commonly called flaggers. Their sole responsibility is to ensure that the work crew is safe from passing trains. They need a place to stand where they will have clear sight of both an approaching train and the work zone. They and the workers also need a place to clear up from a passing train. The engineer must give this some thought when designing a system in order to build in clearance areas and identify no-clearance zones. A simple niche in the wall could prevent someone from getting hit by a train. 14.4.3 FRA 214 Regulations (If Applicable) FRA 49CFR214 lays out rules for the safety of âroadway workersâ on any system connected to the general railroad system. Agencies subject to FRA oversight must adhere to 49CFR214, or fines can be imposed. While, strictly speaking, these rules may not be legally applicable to a given agencyâs LRT operation, they do represent âgood practice.â The track designer should therefore read this document as well as similar APTA-recommended standards to gain additional understanding and knowledge of how the system must be maintained. This should lead to the incorporation of system features that foster a safe working environment and facilitate maintenance activities.
LRT Track and Trackway Maintenance 14-5 14.4.4 Risk Analysis Mitigating risk to a safe level will reduce accidents. Thinking about what could happen might just save someoneâs life. Having an action plan for every conceivable problem that could go wrong may get all the workers home safely to their families. 14.4.5 Preparatory Work In some cases, a work zone can be viewed prior to actual maintenance being performed. This is a good idea that will help develop good work plans and allow the proper tools to be available during the work outage. For example, if a tie is to be changed and the workers arrive on the site to find a piece of loose rail in the way, they will need a tool (rail tongs) to get the loose rail out of the way that they may not have brought with them (because it is not necessary for changing a tie). Now a worker must leave the safe work zone and retrieve rail tongs. This wastes valuable track time as well as worker time. In order to prevent this, a good foreman would have inspected the work zone, possibly by riding a revenue train the previous day, and thereby discovered that rail tongs would be required for this task. 14.4.6 Profile of a Safe Person What constitutes a safe person? If an individual answers positively to five or more, they are relatively safe. Less than five could be an unsafe person, and no positive responses are an accident waiting to happen. We only offer this as general knowledge. Experienced, well trained Feels good about self Alert and clear headed Neat and orderly Not easily distracted Able to follow direction Familiar with equipment Understands objectives Aware of consequences if unsafe Concerned for fellow workers 14.5 INSPECTING THE SYSTEM Only now, after discussing safety above, can we let the reader âget out on the railroad.â Much of this is identified in the APTA track maintenance standards, which are patterned after the Federal Railroad Administrationâs Track Safety Standards, also known as 49 CFR Part 213. The FRA document applies only to those agencies under its jurisdiction. Whichever document is used, the designer should be familiar with it. The discussion below only briefly mentions some inspection activities and priorities. 14.5.1 How Often? On railroads and on parts of rail transit routes that are subject to FRA regulations, the frequency of inspection is typically based on the speed of trains, which in turn identifies a class of track. The FRA Track Safety Standards then identify an inspection frequency based on that track classification. No similar regulations apply to tracks that are not under FRA oversight. However, APTAâs document RT-S-FS-002-02, Standard for Rail Transit Track Inspection and Maintenance,
Track Design Handbook for Light Rail Transit, Second Edition 14-6 stipulates that tracks used in revenue service should be inspected at least once a week and that other tracks should be inspected monthly. An interval of at least 3 but not more than 11 calendar days must elapse between inspections. In general, for the maximum speeds at which light rail trains typically operate, the FRA rules and the APTA standards are consistent concerning inspection frequency. However, rail transit systems that operate discrete track segments at greater than 60 mph [97 km/hr] might consider following the FRA requirement for Class 4 track, which requires twice-weekly inspections. 14.5.2 Priority Lists This list is a valuable tool for the maintainer. One would like to think they could do everything right now, but that is not reality. Therefore, a priority list would be established and conveyed to the maintainers for action. 14.5.3 Qualifications Both the FRA and APTA have developed guidelines to qualify people to inspect track and to oversee the performance of track maintenance tasks. The FRA has established a third classification for persons who are qualified to maintain and supervise work on CWR. This third category has a training component and experience levels since improper maintenance and inspection of CWR has led to serious accidents and fatalities on railways. Understanding how CWR reacts and how the forces due to temperature change and train dynamics must be restrained is imperative. The engineer must have a full and complete understanding of this also. 14.6 MAINTENANCE ACTIVITIES The following discusses maintenance activities unique to each trackform. Writing a maintenance manual may sometimes be the responsibility of the designer. Since each agency may have its own unique character, some generic maintenance activities for certain trackforms will be discussed as listed below. 14.6.1 On-Track Maintenance-of-Way Equipment A maintenance-of-way program requires appropriate equipment to fulfill its function. With the exception of LRT/streetcar lines that are 100% embedded track, much of this equipment will need to be designed to ride on the track. This will include hy-rail vehicles that can run on both the highway and the rails and machines that are rail-only. Because the equipment requirements for LRT maintenance can vary widely, this Handbook will not attempt to address the details of the many types of equipment that might be included in a comprehensive maintenance-of-way program. However, the following critical issues should be kept in mind when specifying and procuring M/W equipment. â¢ The maintenance vehicles must be compatible with the track. This seems obvious, but is often overlooked. The wheel contour and wheel gauge for M/W equipment should ordinarily be identical to that adopted for the light rail vehicles. More than one project has belatedly discovered that on-track maintenance equipment that was manufactured in strict accordance with AREMA recommendations doesnât fit a track structure designed
LRT Track and Trackway Maintenance 14-7 around transit parameters. Differences in back-to-back wheel gauge and the resulting incompatibility with narrow flangeways are distressingly common occurrences. Maintenance-of-way equipment with a long wheelbase may not be compatible with sharp radius curves. Since widening the flangeways to accommodate the rare operation of some machine with a long wheelbase would likely be detrimental to the compatibility of the track with light rail vehicles, it may be necessary to either prohibit such equipment from certain curves or procure an entirely different machine that is compatible with the track. â¢ The track must be compatible with the maintenance vehicles. This is typically an issue with hy-rail maintenance trucks. On one project, it was belatedly discovered that the light-duty material used for walking surfaces on pedestrian crossings was being crushed by the heavy rear tires of the maintenance departmentâs hy-rail trucks. On another project, an extension to a systemâs existing light rail line, it was discovered that the hydraulic jacks on the transit authorityâs tamper would not clear the station platforms along the new track. Restraining rails that are elevated more than about Â½ inch [13 mm] above the running rails can be problematic, as they can lift the rear tires of hy-rail trucks, which then lifts the rail wheels. Since this would occur in a sharp curve (hence the presence of the restraining rail), the rail wheels can then climb over the rail and derail. 14.6.2 Maintenance Issues Common to All Trackforms 126.96.36.199 Insulated Joints Insulated joints are very important because they and the associated signal system circuitry prevent trains from hitting each other. Insulated joints define segments of track that cannot be occupied by more than one train. If an insulated joint fails, the signal system fails, albeit to a âsafeâ condition that simulates a train occupying the track. Insulated joints must remain insulated so there is no continuity from rail to rail. Therefore, they should be checked periodically. Epoxy-bonded insulated joints are typical on LRT systems, but there may be standard bolted insulated joints also. Whichever type is encountered, they must be checked for loose bolts and broken or damaged insulation. The epoxy must be intact. There should be no gap between the end post and either rail. 188.8.131.52 Rail Corrugation and Rail Grinding Rail corrugation and rail grinding are closely related topics that are necessarily addressed together. 184.108.40.206.1 Rail Corrugations Rail corrugations are a form of rail wear that appears on the surface of the rail in a regular pattern. Corrugation is often caused by wheel slippage or dynamic creep. Wheels are tapered for proper tracking of the vehicle. Poorly matched wheel diameters on the same wheel set may cause slippage. This slippage usually happens in the same place all the time, particularly if the vehicle fleet is identical, which is often the case in rail transit. This slippage will cause very shallow ârutsâ in the rail over time. These can cause noise and vibration, a phenomenon commonly called âroaring rail.â
Track Design Handbook for Light Rail Transit, Second Edition 14-8 Corrugation is characterized by two main parameters. One is the length of the âwaves.â This is measured from crest to crest or valley to valley. Depending on the causes of the corrugation, the wave length can be anywhere between Â½ inch [1 cm] to 3 feet [1 meter]. The other parameter is the depth. A good straight edge and taper gauge can measure this dimension. Each property should have some criteria for these parameters. In many cases, the people in the neighborhood will bring this roaring rail noise to the transit agencyâs attention. The stiffness of the track (track modulus) plays a role in corrugation also. If the track is either too stiff or too soft, corrugations may develop. Finding the right stiffness for the loads imposed on the track is a challenge. The track designer should have a good understanding of this before selecting or specifying a rail fastener or setting the fastener spacing; see Chapter 9 for additional guidance on this topic. The track stiffness will be different in switch areas and the frog area also. It is the maintainerâs job to identify corrugation and implement corrective action before it becomes significant and causes wheels to jump or flutter. Left uncorrected, corrugations only get worse as their vertical amplitude increases. The resulting oscillations in the vehicle trucks will also cause the corrugation pattern to progress further and further down the track. 220.127.116.11.2 Rail Grindingâthe Basics Rail grinding is both an art and a science. Books have been written about it; however, very nearly all research has focused on rail grinding for open track on freight railroads. While much of that is applicable to any steel-wheel-on-steel-rail system, the smaller wheel loadings of rail transit change the parameters and hence the results that can be expected. Rail grinding is commonly done to restore the original contour or make a new profile to better suit the wheels. The key to success is to match the wheel to the rail whereby the contact patch is optimized for proper load transfer. Besides the elimination of corrugations and the associated noise and vibration, other benefits to rail grinding include removal of rail defects that are initiated by rolling contact fatigue of the rail steel, lower rolling resistance, improved traction, and reduced energy consumption. While it seems counterintuitive, removing rail steel through grinding actually extends the life of the rail, because rail wear rates are reduced by optimizing the rail/wheel interface. Grinding will also produce better contact between the rail and wheel to both reduce electrical resistance for the negative return path and improve shunting for the signal system. 18.104.22.168.3 Rail Grinding Frequency Rail grinding can be used for both preventative and corrective maintenance. Some studies suggest that a regular program of periodic rail grinding can extend rail service life by 30% or more. Unless corrugations are ground out early, the work-hardened metal at the valleys of the corrugations will extend to significant depth below the running surface. Once that occurs, even if corrective rail grinding is performed, the corrugation pattern may be quickly reestablished. Eventually, the condition may become so intractable that the rail will need to be replaced at only a fraction of what its service life would have been had rail grinding been done early and often. In general, rail grinding done before the corrugations are plainly visible or audible is best, since it will prevent the steel from becoming work hardened beneath the corrugation
LRT Track and Trackway Maintenance 14-9 valleys. Careful monitoring of corrugation growth rates are necessary to determine an optimum grinding interval, which may be the time required for the corrugation amplitude to increase by a factor of two or three relative to some reference condition. Corrugation growth is largely exponential. 22.214.171.124.4 Specifying a Rail Grinding Program Rail grinding, if done improperly, can cause more problems than it solves. This section simply offers some guidelines to keep in mind. Very few transit agencies have the resources to own and maintain their own rail grinding equipment. Instead, most agencies procure rail grinding services from specialty contractors. This requires the preparation of a detailed contract specification. Whether the specification defines specific methods or is performance based, it must convey a message tailored to the needs of the individual LRT system. Since LRT systems vary a great deal, it is nearly impossible to suggest that one size fits all. The ownerâs specifications should define the following: â¢ The characteristics of the rail system, particularly any factors that might impact the grinding contractorâs equipment. â¢ The conditions under which the grinding program must be performed. â¢ The desired end product. This part could vary considerably depending on the ownerâs objectives, previous experiences with rail grinding, and the degree to which the owner wants to depend on the contractorâs expertise to âdo the job right.â Rail system characteristic factors that should be defined include the following: â¢ Trackform(s) and rail section(s) to be ground. â¢ Wheel profile and wheel gauge. â¢ Rail cant and track gauge. â¢ Maximum grades and minimum curvature. This is best addressed by including complete plan and profile drawings as an appendix to the specification. â¢ Details of track appliances found in the tracks to be ground. In particular, the contractor will be concerned about guard rail systems since they can affect the ability to position grinding stones around the gauge corner of the rail. Both restraining rail flangeways and the clearances to any emergency guard rails can affect the contractorâs methods. â¢ Wayside clearances, particularly in tunnels and station platforms. Even low-level platforms can possibly obstruct equipment that was originally designed to work on a freight railroad.
Track Design Handbook for Light Rail Transit, Second Edition 14-10 Working condition requirements could include the following: â¢ Time of day limitations. Can track time be made available during the day or will all of the grinding need to be done on nights and weekends? How soon after the last train can the contractor get started? How much time must be allowed at the end of a work shift to clear the track? â¢ Contractor storage location(s). Like all contractors, the rail grinding contractor will need laydown space for the rail grinding train and off-track equipment and materials. The maximum traveling speed of most rail grinding trains is relatively slow, and the contractor will generally prefer to maximize his âspark timeâ by not running to and from the systemâs main storage yard at the end of his shift. Pocket tracks or spurs where the grinding train can be stored when not in use can significantly increase the contractorâs productivity and decrease costs. â¢ Safety requirements, such as flagging of rail and automotive traffic. â¢ Environmental conditions. What are the maximum tolerable noise levels that will be allowed during the work? Will they vary by time of day and/or location? â¢ The rail surface finish tolerances they will be expected to produce. These metrics are often understated, especially by owners and consultants who have insufficient experience in rail grinding work. â¢ Will the third rail or overhead catenary be energized while the contractor is performing the work? â¢ What form of track protection will be in place? â¢ Must the grinding equipment have the ability to shunt the rails? The rail grinding contractor should make several detailed submittals prior to mobilizing equipment to perform the work. Items that these submittals address could include the following: â¢ A detailed inspection report of the existing track, defining the existing condition of the rails with respect to corrugation and wear and highlighting any areas that may need special attention. This report may have been prepared in advance by the owner or a consultant who has been retained by the owner. Even so, the rail grinding contractor should be required to conduct an inspection and confirm whether this inspection corroborates the ownerâs or ownerâs consultantâs findings. â¢ A detailed work plan describing how the contractor intends to perform the work. This would include the following: â Specifications on the equipment to be used, including clearance diagrams of the equipment to be used.
LRT Track and Trackway Maintenance 14-11 â Any limitations the equipment may have, such as the minimum radius the equipment can traverse and whether it can operate on non-standard gauge track. â Environmental controls such as the dust collection, fire protection, and spark- arresting systems, as well as the system for collection and disposal of rail grinding debris. The debris might be considered hazardous material in some jurisdictions, and proper disposal is mandatory. The contractor should explain how the drainage system will be protected from becoming clogged with grinding stone particles and metal dust and also specifically explain how the metal dust will be prevented from breaching the signal system or creating a path for stray current. â How the contractor intends to perform the work. This would include the size, type, and number of grinding stones to be used, including the grit size, the number of passes that will be made on each discrete segment of track, the pass speed, and the number of facets that will remain on the rail head at the completion of the work. The size of the grit in the grinding stones is an important issue for rail transit. Rail grinding on freight railroads can generally use stones with a fairly coarse grit since the heavy axle loadings will smooth the surface fairly quickly. The same coarse finish on a transit line might take months to wear away, especially with hardened rail. Moreover, during that wearing-in period, noise levels could actually be increased, and the periodic grinding marks in the running surface could initiate new patterns of corrugation. â A schedule for when the work will be performed in each discrete segment of the route, including how the work will interface with rail transit operations. â A description of and references for previous similar work performed on other rail transit properties. 126.96.36.199.5 Special Challenges for Transit Rail Grinding There are many challenges that make grinding rail on a rail transit system distinctly different than similar work on a freight or passenger railroad. These include the following: â¢ Rail grinders will produce sparks that can cause fires or damage, including eye injuries if bystanders are watching the work. Since LRT rights-of-way are typically much closer to the general public than freight railroad tracks, special measures are necessary to protect the public. â¢ Rail grinding is a noisy operation. This issue must be addressed as part of the bid documents for procurement of rail grinding services; otherwise, the operation might be shut down on the first night by neighborsâ complaints. â¢ Rail grinding can be especially challenging on metro rail systems that use a third contact rail for traction power distribution since metallic grinding dust can cause leakage around insulators on both the negative and the positive sides of the traction power circuit.
Track Design Handbook for Light Rail Transit, Second Edition 14-12 â¢ Rail grinding in embedded track has unique challenges; see Article 188.8.131.52 for a detailed discussion of these issues. 184.108.40.206 Repair Welding and Grinding of Switches and Frogs This is another important activity that will allow the switch points and frogs to achieve the maximum life possible. Monitoring wear of frogs and switch points should be performed by the maintainer. Periodic measurements will facilitate predicting when the frog or switch point will be worn more than the criteria given in the maintenance standards manual. The measurements must be taken at regular intervals such as every 3 to 6 months. Switch points and frogs can be welded back to their original shape using the correct material and workmanship. This is a job for professionals who have been trained to weld switch points. If an untrained individual performs this work, there is a high probability of weld defects that can propagate and develop into cracks that can cause the tip of the switch point to break off completely and create an obvious high risk for derailment. 220.127.116.11 Emergency Repairs It is important that these activities be identified in the system maintenance standards. What constitutes an emergency? Wear on rail is not an emergency. A track buckle is an emergency! Every reasonably possible problem or occurrence should be identified in the maintenance standards and categorized as to whether it should be considered an emergency or not. Risk analysis can play a very important role in deciding the definition of an emergency. Each emergency must have an emergency response plan designating what actions are required and/or are allowable, or are prohibited. These are decisions that the property owner must resolve based on local conditions. For a new rail system, where the owner may not yet have experienced rail personnel on staff, the track designer may be the ownerâs best resource for making these decisions. A few examples of situations that might be addressed in the plan include the following: â¢ In an emergency situation, it is generally accepted that a torch may be used to cut the rail, but specific conditions might rule against that. â¢ Designating the number of fasteners in a row must become ineffective before an emergency is declared. â¢ Designating how far back a switch point must break before an emergency is declared. It is imperative that these decisions are made prior to commencement of revenue service. 18.104.22.168 Maintenance Documentation Records of inspection and maintenance activities should be kept up-to-date and contemporaneous with the work performed. Such records can make future maintenance easier, but the more important reason to keep comprehensive records is as a legal protection. Records are needed to be able to prove that inspections and maintenance have been performed on a timely basis. The following agencies and organizations have certain levels of regulation and/or oversight with respect to rail transit, including maintenance documentation. It is strongly recommended that each designer be familiar with salient documents published by these concerns.
LRT Track and Trackway Maintenance 14-13 22.214.171.124.1 The Federal Railroad Administration The Federal Railroad Administration (FRA) regulates trackwork that is part of the general railroad system of transportation and has some oversight of tracks that, while they are not part of the general railroad system, are proximate to FRA-regulated tracks. While much of the FRAâs specific inspection and maintenance requirements may not apply to a rail transit line, FRAâs requirements for record-keeping, as published in 49 CFR 213.241, represent good practice that should be considered during the development of a system maintenance plan. 126.96.36.199.2 The American Public Transportation Association The American Public Transportation Association (APTA) has written safety standards which can be downloaded from its website. It consists of six volumes entitled: (1) Background and Process (2) Vehicle Inspection and Maintenance (3) Rail Grade Crossings (4) Operating Practices (5) Fixed Structure Inspection and Maintenance (6) Signals and Communication Inspection and Maintenance The APTA documents are generally in the same format as the FRA regulations but also include a color-coded priority system to offer guidelines on severity. The APTA documents are voluntary standards and, as noted earlier, are necessarily generic because of the wide variation in transit system infrastructure and systems from one transit agency to another. 188.8.131.52.3 The Federal Transit Administration The Federal Transit Administration (FTA) has the task of overseeing transit agencies, but, unlike the FRA, the FTA does not (as of 2010) have the authority to govern transit operations or to levy fines. The FTA principally administers funds to build and maintain transit systems. In the process of administering those funds, the FTA does have the discretion of requiring compliance with standards, codes, and requirements developed by other public agencies and private entities. 14.6.3 Embedded Track Maintenance Requirements 184.108.40.206 Cleaning the Flangeways Unless the track gradient is steep enough so that ordinary storm water runoff will flush debris out of the flangeway, it will fill up with all sorts of street detritus. While there is a slight danger of this material causing damage to the LRV wheels, the real danger is that the rail insulation system (typically a rail boot) will be compromised and that trace amounts of stray current will be able to leak off the rail over an extended length of track. It might also affect train control system circuitry if track circuits are used. This is a situation where groove rail has an advantage over tee rail with a formed flangeway. Frozen debris in a flangeway could also cause a derailment. Avoiding very flat grades and providing frequent track flangeway drains are measures that the track designer can take to make certain the flangeways remain clear. When flat grades are unavoidable, the owner should be advised that additional maintenance effort should be expected (and budgeted for) to keep the flangeways clear.
Track Design Handbook for Light Rail Transit, Second Edition 14-14 At one LRT system in Germany, a specially equipped rail grinding vehicle also includes a flangeway scraping tool with a vacuum system for cleaning the flangeways of groove rails. Such a system might not work as well on embedded tracks using tee rail because the scraping tool might damage the pavement and the rail boot or other rail isolation system. The LRT system in Calgary has a vacuum truck that is designed specifically to clean flangeways. 220.127.116.11 Repair Top Surface Spalls and cracks in the roadway surface should be repaired/sealed and not left open for long periods of time. This is another avenue for water penetration into the underlayment, which can cause destruction of the embedded track system over time. 18.104.22.168 Spotting Stray Current Learning the signs of stray current leakage and corrective actions to be taken early can save a system the cost of a major track reconstruction. It may begin with spalling of the concrete surface or false indications to the signal system. Observing minor arcing during wet weather at night could be an indicator. Track drains are likely locations for stray current leakage and should be inspected and cleaned frequently. While stray current may take years before it becomes a hazard, regular inspection and preventative maintenance are recommended. A professional corrosion consultant should be retained to test the system annually and identify any âhot spotsâ so that they can be corrected before they cause severe damage. 22.214.171.124 Snow Removal When a rail vehicle encounters snow or ice on a rail head, the extremely high contact pressure between the wheel and rail will typically cause the ice to melt despite the cold temperature. This is the same phenomenon that enables a figure skater to glide across the ice. Because of this, light rail vehicles can be as sure-footed through light snowfalls as they are in the rain, particularly when equipped with sanders. However more than 2 to 4 inches [about 5 to 10 cm] of snow over the rails can be problematic, particularly on steep grades or if ice has filled the flangeways. Accordingly, removal of snow and ice from embedded tracks is an important activity. Typically, ordinary snowplow trucks can be used although some systems have used locomotives equipped with plows. Legacy streetcar systems often had snow sweepers, but no such vehicles are currently in use in North America. Snow that is contaminated with dirt, cinders, and de-icing chemicals can also compromise track insulation systems, lead to erratic signal system operation, and become a path for stray current. 126.96.36.199 Repair Broken Rail While a broken rail in embedded track is generally not as severe a hazard for derailments as one in open track, it interrupts the traction power negative return and hence could result in a major stray current problem at an entirely separate location. Broken rails therefore should be promptly repaired. Even if a full repair isnât immediately possible, a rail bond cable should be installed around the break until a full repair can be made. Repairing a broken rail (or a worn-out rail) in embedded track is tedious and expensive as it requires concrete removal over a significant distance so a new rail plug can be installed. The integrity of the rubber rail boot or other isolation system must be restored before the pavement can be restored.
LRT Track and Trackway Maintenance 14-15 The concrete surface must be saw cut on either side of the rail a distance that will expose the fastening system when the concrete is removed. The concrete is then chopped out to a depth near the base of rail. The elevation is already preset by the elevation of the existing concrete under the rail; therefore, the concrete can be rough adjacent to the base. The fasteners are exposed and can be removed. The boot can be cut back to where the rail is to be cut, allowing enough room for a repair cuff to be installed. The thermite weld and the rail boot repair cuff will both require concrete demolition to well below the base of rail. Hydro-demolition is sometimes convenient for that purpose, but the area must be thoroughly dried before the thermite weld is made. After the rail is cut, the old rail can be removed as well as the old boot. The concrete surface should be cleaned at this time and a visual inspection performed. Any damaged coatings on exposed reinforcing steel will need to be patched. The new piece of rail can be booted and set into the seat area established by the old rail. Fasteners can be reinstalled, welds made, and the boot cuffed and tested. After a quality control check, the concrete can be replaced and revenue service restored. 188.8.131.52 Replace Worn-Out Rail It generally takes a very long time for rail to wear out in the LRT environment. Significant wear will usually be observed only in sharp curves or at locations where heavy braking occurs. Stations/stops are usually locations of accelerated top-of-head rail wear due to occasional use of track brakes. The rail replacement issue led to some early embedded track designs that tried to facilitate rail change-out by making it easy to access the base of the rail. The problem with such designs is that the features that make it easy to access the rail fastenings also make it easy for water and contaminants to access them and possibly initiate corrosion. The use of a harder grade of steel rail is usually a better investment since it makes it far less likely that the rail will wear out prematurely. Ideally, the service life of the rail will match or exceed the service life of the embedding pavement. If a section of embedded rail needs to be replaced because of wear, the process is generally as described above for a broken rail. 184.108.40.206 Replacement of Parts in Embedded Specialwork Advance planning for replacement of parts in embedded special trackwork must be incorporated in the design and fabrication. The most likely parts to require replacement are the switch tongues and the switch machines, including the connecting hardware to the tongues. The procurement specifications need to include requirements that it should be possible to replace those items without demolition of pavement. Ideally, this work should be possible using ordinary hand tools to remove and reinstall fastenings and a light capacity crane to remove and reinstall the major components. 220.127.116.11 Rail Grinding in Embedded Track Because flangeways in embedded track (as well as in grade crossings along open trackforms) are so narrow, a rail grinding contractor must use different rail grinding stones in embedded track that may require an entirely different methodology than with open trackforms such as direct fixation and ballasted. It is difficult to grind rail in embedded track and conventional grinding equipment may not work properly. The development of longitudinal belt sanders may be the answer for embedded type track.
Track Design Handbook for Light Rail Transit, Second Edition 14-16 Many light rail systems in Europe have specially equipped rail vehicles for performing preventative maintenance rail grinding. These cars are often older high-floor articulated vehicles that are no longer being used for passenger service. The center truck on such cars is equipped with grinding blocks that take the place of the magnetic track brakes. Hydraulic pistons can maintain a constant downward pressure on the grinding stones. These rail grinding cars are run over the system on a regular schedule, often running at relatively high speeds between revenue service trains during daylight hours. The cars are often equipped with tanks to spray cooling water on the grinding stone as well as a vacuum system for collecting the spray water and any grinding residue. The routine use of such block grinding cars has been proven to defer the need for corrective grinding with conventional rotary rail grinding equipment and, in some cases, prevents corrugations from ever reaching a level where corrective grinding is even necessary. Curiously, many legacy North American streetcar systems used similar equipment in times past, but the practice fell out of favor for reasons that are no longer clear. It may have been simply a matter of the equipment getting old and difficult to maintain. As of 2010, at least one North American LRT system was going to be procuring modern block grinding equipment based on current European practices. 14.6.4 Direct Fixation Track Maintenance Activities Direct fixation track is an âopenâ trackform with nearly all of the major components easily visible and accessible for inspection and maintenance. Other open trackforms include ballasted track, some forms of grass track, and open deck bridge track. The paragraphs below will discuss various maintenance activities that are applicable to direct fixation track and may also be applicable to other trackforms as well. 18.104.22.168 Tighten Bolts While the use of CWR eliminates most bolts in rail, direct fixation track is loaded with other bolts. These include rail fastener anchor bolts, emergency guard rail bolts, and numerous nuts and bolts within special work. Systems incorporating a contact rail instead of overhead catenary will have dozens of other types of bolts. Every one of these bolts is subject to loosening. If one bolt becomes loose, the adjacent bolts must restrain the dynamic forces triggering them to loosen or break in turn. New track is particularly prone to bolt loosening until such time as mating parts wear in and seat to each other. The designer can assist in this by avoiding designs that incorporate threaded fastenings in inaccessible locations where both inspection and tightening are difficult. 22.214.171.124 Rail Clip Maintenance Elastic rail clips, which are fabricated from spring steel, require regular inspection and occasional replacement. Since parts of the clip are highly stressed, they can be particularly susceptible to corrosion and sudden failure. Exfoliated rust from the rail clips has been known to become impacted between the clip and the clip housing, making it impossible to remove the clip (or the broken stub of a clip) from the housing. This sort of problem is common within damp tunnels.
LRT Track and Trackway Maintenance 14-17 Designers should carefully consider whether particular trackway environments might not be suitable for some products (such as a particular rail clip design) due to environmental conditions, loadings, or both. Prior to soliciting bids for such items, the service environment where the product will be used should be made very clear to potential vendors and their advice solicited concerning the most appropriate products to be used. The manufacturerâs recommendations concerning installation, inspection, and maintenance should be incorporated in the system maintenance manuals and closely followed by maintenance staff. 126.96.36.199 Housekeeping Direct fixation track can provide extremely long service if properly constructed and maintained. A significant part of that maintenance is simple housekeeping. Trackways are dirty environments and that dirt needs to be washed off the track at frequent intervals. For ordinary direct fixation track out in the open, normal precipitation is sufficient to keep the track clean. But tracks in tunnels obviously do not see rainfall and tend to accumulate all sorts of dust and dirt. If the tunnel is damp, this material tends to be corrosive and attacks the rails, rail fasteners, and other appurtenances. LRT tunnels in regions that get snowfall and see heavy use of de-icing chemicals are particularly susceptible to extremely severe trackway corrosion. The LRVs will pick up corrosive slush at road crossings and embedded track segments and carry that material into the tunnels where it will melt and land on the track system. This corrosive brine not only initiates corrosion chemically, it provides paths for stray currents, causing even more accelerated corrosion. Several LRT systems have needed to completely replace rails and rail fasteners in such tunnels, while identical construction in other areas of those systems that were not subject to brine attack remain in nearly new condition. The primary defense against this sort of problem can be relatively simple. Completely washing tunnel trackwork with the equivalent of a âfire hoseâ on a regular basis (say twice a year) can remove the brine and other contaminants before they can cause significant corrosion. The debris can be washed toward tunnel drains where solid particles should be collected rather than being passed through to municipal sewer systems. Direct fixation tracks in LRT stations tend to accumulate traction sand beneath the rails and between the rail fasteners, sometimes mixed with lubricants that drip from the vehicles. This compound can also cause corrosion and stray current problems and should be power washed away on a regular basis. 188.8.131.52 Regauging Track for Rail Wear When the rail begins to wear on curves, it may be necessary to adjust the gauge in order to stay within maintenance standards for gauge. If âzero adjustmentâ fasteners were installed during construction, then it is not possible to do this without core drilling and moving the inserts; however, most fasteners have adjustments built into the anchorage assembly for adjusting gauge and line up to Â½ inch each way from center. Provided the constructor didnât use all of this adjustment during construction, the maintainer should be able to correct the gauge. Preserving this capacity makes it very important that the contractor center the anchor assemblies during construction. As noted in Chapter 13, the use of top-down construction greatly facilitates this by preserving virtually all of the lateral adjustment capacity.
Track Design Handbook for Light Rail Transit, Second Edition 14-18 184.108.40.206 Repair Cracked and Spalling Concrete Cracks happen, and, as noted for embedded track, they should be sealed so no water enters the interior of the concrete. If this occurs, then water may begin to rust the reinforcing steel; more importantly, this gives a path of least resistance for the stray current. In colder climates during freeze/thaw cycles, the frozen water could spall the concrete, leaving a large exposed area. Fixing minor cracks is relatively easyâa small handheld chipping gun is used to chisel or âVâ out an area along the crack. Then caulking or some other flexible watertight material can be used to seal the crack. 220.127.116.11 Repair Caulking Some designs require that a bead of caulking be placed around the plinth. This is primarily to prevent water from getting under the plinth and causing the same problems that may be encountered from spalls or cracks. If the original caulking becomes ineffective, it should be removed. The area must then be prepared according to the caulking manufacturer and a new bead of caulk applied. 18.104.22.168 Repair of Broken Rail When a rail breaks, it is usually because of excessive tensile force that has built up in the rail due to cold weather or train dynamics. If this occurs in direct fixation track on an aerial structure, significant problems could ensue due to unbalanced forces among the structure, the broken rail, and other unbroken rails on the bridge. It must be understood that when such a system is built, the interface between the guideway and the rail is correctly matched and should not be changed. Therefore, it is imperative that no rail be added. The main issue when repairing any CWR break is to not change the neutral temperature of the rail. Simply welding in a new rail plug will cause problems when the rail gets hot. In ballasted track and also in direct fixation track on a structure, there could be major problems if the neutral temperature of one rail is significantly different from the other rail on the same track. The CWR plan that every track owner must have needs to explain the procedure for correcting this defect. Typical plans for the correction of a broken rail are several pages long, but the bottom line is to pull the rail back together after removing at least 200 feet [60 meters] of rail clips each way, then weld the rail back together. In general, there should be criteria for breaks less than 3 inches [75 mm] and more than 3 inches. If the break is more than 3 inches, a plug rail must be put in, but the CWRâs zero stress temperature must be readjusted prior to the return of warmer spring weather. It is also imperative that these activities be documented. If a rail break occurs near this location again, then the rail may need to be de-stressed again for a much longer length. Refer to Chapter 13 for more detail on adjusting CWR for optimal zero thermal stress. 22.214.171.124 Replacing Rail Fasteners Occasionally, a fastener may break or become ineffective. Maintenance standards should address how many rail fasteners in a row or within a section of track may be defective just as standards do concerning defective crossties. Replacing an individual fastener that is anchored to female inserts embedded in the plinth is a relatively easy task. Simply remove the clips and hold-down bolts. Raise the rail after removing a few clips on either side. Then, slide the fastener out and install a new one. Lower the rail, reclip
LRT Track and Trackway Maintenance 14-19 every fastener, and torque the hold-down bolts to the correct torque. While the fastener is not there, it is wise to inspect the concrete under the fastener to determine what caused the fastener to fail. If any voids are found under the fastener, they should be repaired before installing the new fastener, or the new one will become broken in a period of time. Sometimes it may be determined that the anchor inserts sit above the plane of the concrete surface, causing point loads directly on top of the inserts. If this is the case, the top of the inserts should be ground flush with the surface of the concrete and then epoxy paint applied to the bare steel. Fasteners that are anchored using threaded rods rather than female inserts require that the rail be raised very high in order for the defective fastener to be removed. This requires the unclipping of much more rail, which could result in the rail bucking in hot weather when compressive forces in the rail are high. For this reason alone, the use of female inserts rather than threaded rod anchors is preferable. In all cases, it is wise to do this activity when the rail temperature is below the neutral temperature. In the maintenance manual for the system, stipulate the maximum number of rail clips in a row that may be removed. Several rail transit systems have needed to perform out-of-face replacement of long segments of direct fixation rail fasteners, usually in track segments constructed in the 1970s or 1980s. Many of the rail fasteners used at that time were inferior designs that did not hold up well under service. These out-of-face replacement projects have more in common with new construction than with ordinary maintenance work. 126.96.36.199 Rail Fastener Anchor Insert Replacement Occasionally, for whatever reason, an insert may fail or the threads become ineffective. If this happens, then the insert must be removed and a new one put in. The replacement process is to remove the defective insert by core drilling and grouting a new insert in its place. Once the rail fastener is temporarily removed, core drills can make this work relatively quick and easy. It is very important to ensure that the new insert is perpendicular to the bottom plate of the fastener, is either even with or slightly below the surface of the concrete, and is not in contact with the sides of the cored hole. Only then should the insert be anchored in place, typically with a two- component epoxy grout. Either templates or the fastener itself should be used as a guide for positioning the new insert. It is very important to follow the grout manufacturerâs recommendations, particularly environmental controls such as temperature and keeping the work area dry. 188.8.131.52 Replace Continuous Welded Rail It is important to ensure that no rail is added or subtracted which will change the neutral temperature and cause unnecessary forces to be imposed onto the guideway. Track time is always a concern for doing this activity. The fasteners will play a role in the speed and effectiveness of performing this activity. If female inserts are used with bolts to attach the fasteners to the invert, only the rail clips will need to be removed and the new rail installed. If threaded rods are used to anchor the rail fastener body to the invert, they frequently project some appreciable distance above the fastener. If so, the rail must be lifted over the rods when removing it from, or placing it in, the fastener seat since impact could render the rods unusable
Track Design Handbook for Light Rail Transit, Second Edition 14-20 Many rail transit maintenance organizations, particularly on smaller systems, will not have the proper equipment and trained personnel necessary to correctly and efficiently perform out-of-face replacement of CWR. In such cases, it may be an activity best assigned to a qualified track contractor. 184.108.40.206 Replace Parts in Special Trackwork There are numerous pieces and parts that make up a specialwork portion. The owner should have a full complement of replacement parts, and, when one is used, an order for restocking should be immediate. As the inspector walks each special portion weekly, they will generate a list of deficiencies. These lists should be monitored periodically to confirm compliance with maintenance standards. The challenge for the supervisor is to determine when corrective action should take place. In any case, corrective action should take place before the defects become too many. Minor bolt tightening and clip adjustment should be done on a weekly basis. Some parts such as frogs, switch points, and guard rails may require a contractor with the equipment to perform the work. 14.6.5 Ballasted Track Maintenance Activities Ballasted track, like direct fixation track, is an âopenâ trackform; thus, many of the maintenance activities described above for direct fixation track will also apply to ballasted track. The paragraphs below will address some of the activities that are unique to ballasted track. 220.127.116.11 Ballast Maintenance Ballast is an important part of the track structure for controlling thermal forces. The correct cross section of ballast therefore must be maintained in order to keep the track stable. Ballast may begin to migrate away from the ties, and therefore must be replaced or moved around. If tamping is to be done, it is advisable to place ballast first in excess to accommodate the tamping cycles. That way the track does not become unstable during the tamping operations. The track inspector should always look for areas with weak ballast, and any such area should be repaired as soon as possible, particularly during hot weather. Ballast cleaning is a common activity on freight railroads but is rarely undertaken on rail transit lines. The best approach to avoidance of any need for ballast cleaning or replacement is to use a good hard ballast stone to begin with and to then keep up with basic housekeeping, including maintenance of drainage systems. 18.104.22.168 Surface Track Ballasted track can be expected to settle and shift over time. This is a normal thing and actually helps track stability so long as it is uniform and does not create any abrupt horizontal or vertical misalignments. When this happens, it is necessary to raise and tamp the ties to restore a good surface. Extra ballast is placed first in the area of the track that has settled. Then the track can be raised and tamped without affecting the neutral temperature or the stability of the track. The track looses stability just after it is raised, so operating rules must be followed with respect to a slow speed order after maintenance has been performed. Alternatively, a stabilizer could be used to restore the track modulus.
LRT Track and Trackway Maintenance 14-21 22.214.171.124 Repair Deflector Ramps at Crossings Every crossing should have deflector ramps that prevent dragging debris from abruptly getting caught on a sharp edge and causing damage. These ramps should be repaired immediately if damage occurs. 126.96.36.199 Replace Pads and Insulators on Cross Ties Over time the pads and insulators that are part of the rail fastening assemblies on concrete cross ties will wear, crack, or otherwise become defective. This could compromise both the structural integrity of the cross tie and the electrical isolation of one rail from the other. As explained above for replacement of direct fixation rail fasteners, care must be taken so as to avoid having the rail buckle. It is generally inadvisable to do this work when the rail is above its neutral temperature or outside of the working range identified by maintenance procedures. Working in very short sections or isolated locations should not affect the neutral temperature or hurt the stability of the track. It is good practice to replace the insulators at the same time the pads and or rail clips are replaced. 188.8.131.52 Replace Cross Ties (Timber and Concrete) Wood ties become rotten and damaged, and concrete ties become broken or abraded. When this occurs beyond the limits of the track standards, then the ties should be replaced. A good tie maintenance program is critical to the cost-effectiveness and safety of the railway. During the weekly inspections, a track walker may identify certain ties that are defective. The supervisor must plan tie replacement activities properly. Replacing timber ties is relatively simple because once the spikes have been pulled, the tie can be pulled out to the side without raising the rail. This assumes there is sufficient lateral clearance on one or both sides of the track to extract the old tie and insert the new one. If not, it may be necessary to remove ballast and then respace several ties tightly while the defective tie is rotated 90 degrees and lifted out from between the two rails. The new tie is then installed, the tie spacing is restored in the reverse order, the ballast is reinstalled, and all disturbed ties are tamped. This is a tedious process that requires a lot of manual labor and, hence, is very expensive. For this reason, curbed ballasted track sections are undesirable. So as to minimize future tie replacement costs, it should be possible to extract and replace ties from at least one side of the track, preferably without fouling the other track. Concrete tie replacement can be more challenging because the shoulder embedded in the concrete tie typically requires the rail to be raised by 2-inches [50 mm] so the tie can be extracted. The rail clips on the adjacent ties will need to be removed so the rail can be lifted without disturbing the bedding of the adjacent ties in the ballast, thereby risking âhumpingâ the track. As with timber ties, spot replacement of individual ties in a curbed ballast section can be tedious and expensive, especially since the heavier concrete ties cannot be handled by manual methods. 184.108.40.206 Vegetation Control Vegetation must be kept in check so it does not interfere with the operatorâs line of sight, particularly the view of signals, crossings, and any areas where pedestrians might be on or near the track. At highway crossings, vegetation control needs to be more expansive so that sight triangles in the crossing quadrants are not obstructed. Vegetation should not block any signs or
Track Design Handbook for Light Rail Transit, Second Edition 14-22 signals and must not interfere with track inspection or maintenance. There are professional services that can be contracted in order to keep vegetation from becoming a defect. The track alignment designer should attempt to configure crossings so that the sight triangles remain clear. Sometimes, other disciplines on the design team, not understanding the safety and maintenance issues involved, will wish to plant vegetation in locations where it would become a problem for the maintenance organization. 220.127.116.11 Drainage Maintenance Drainage is a very important aspect of good track maintenance. The water must flow, and the drainage system must be capable of handling the unexpected. It is considered a track defect for any drain pipe to be clogged or even just partially blocked by an object such as a tie, a pile of tie plates, or simply trash. Since most rail transit systems are built in urban areas, trash can be a problem and must be cleaned up promptly. APTA suggests that rail operations should be suspended when water levels get up to the ball of the rail. Even water levels at the base of rail can play havoc with the signal system and also make for problematic conditions concerning traction power return currents. Ditches, culverts, cross drains, under drains and other drainage systems therefore must be kept free of debris. Railway/highway crossings can be very susceptible to flooding if the pavement slopes toward the track and the designers didnât include sufficient drainage infrastructure to intercept storm water before it gets to the track. In direct fixation track, blowing debris that can get caught in track and signal appliances can block drainage. Such blowing debris can also become a fire hazard, particularly on a metro rail system powered by a third rail. Understanding that trash will blow in the direction of train traffic is a simple concept, and âtrash catchersâ bolted to the invert in stations can intercept debris before it can reach a location where it can cause greater problems. 18.104.22.168 Yard Cleaning Yards tend to be collectors of trash and debris and must be cleaned also. Most yards are where workers will clean the vehicles, and workers will congregate before going out on the system. Good housekeeping in yards is also important and will set the tone for workersâ attitudes. There are certain forms of equipment that are designed to clean trash. They may blow the trash to a collection point or vacuum it into a collection container.
Abbreviations and acronyms used without definitions in TRB publications: AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACIâNA Airports Council InternationalâNorth America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation