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35 4.1 Purpose and Structure This guidance applies to the introduction, operation, and maintenance of LFLRVs of a specific type (i.e., three-section cars with the short center section carried on an unpowered truck having IRWs). This guidance covers infrastructure as well as the vehicles themselves and is state of the art, subject to the limitations of this and earlier research programs. This guidance is confined to measures identified in this research as a means of mitigating specific performance issues (i.e., derail- ment, wheel and rail wear, noise and poor ride). This guid- ance has been designed to be clear, applicable, and easy to refer to by the intended users: ⢠Transit agencies that operate or plan to operate LFLRVs, ⢠Rail vehicle and infrastructure maintenance organizations, ⢠Rail vehicle manufacturers, ⢠Rail vehicle sub-suppliers, ⢠State regulatory and oversight authorities, and ⢠National bodies. The application of the guidance will differ for existing and planned new systems. On existing systems, decisions requir- ing changes must allow for the costs of modifying infrastruc- ture and vehicles, whereas on new systems best practice may be designed in from the start. Recommendations for modify- ing vehicle designs for future orders will not be implemented immediately by suppliers, implying a tiered approach. Table 4-1 shows the range of possibilities in terms of time frame. âExisting vehiclesâ refers to LFLRVs operating on transit systems in the United States and Canada and remaining in use on those specific systems.âVehicles currently availableâ refers to vehicles that might be transferred to another system or new vehicles built to the same design or a design in use on other systems worldwide. It has been assumed that a ânewâ system will start with total freedom to specify and use whatever vehicles and infrastructure it chooses, subject only to U.S.and Canadian legislation and reg- ulation. This may not always be the case, even with a totally new system, in that the system may be using some existing infra- structure or be constrained in other ways. The guidance only covers those elements of specifications that directly influence the performance of LFLRVs; other elements must not conflict with these. Users of the guidance need to bear these points in mind. Existing systems also may be able to make infrastructure modifications over time and to introduce new standards for extensions and new projects. Existing systems also may pro- cure new vehicles in the near future (e.g., if a market else- where can be found for the LFLRVs they are currently using). Most issues are likely to be âsystem issuesâ(i.e., resulting from the combination of vehicles and track), so moving vehicles between systems may either solve or worsen these issues. Guidance is split into section headings to facilitate this tiered approach. The sequence is based on the timescale asso- ciated with introducing vehicles now adopting best practice in future, as follows: ⢠Vehicle standards, ⢠Vehicle selection issues, ⢠Vehicle maintenance, ⢠Vehicle modification, ⢠Future vehicle design, ⢠Infrastructure standards, ⢠Operation of LFLRVs, ⢠Infrastructure maintenance, ⢠Infrastructure modification, and ⢠Best practice for system design. Each of these sections is further divided into specific com- ponent areas, organized and presented to be easily accessed and referenced. Cross references are supplied to other chap- ters of this report to indicate why the guidance is given so that users can gain a full understanding by making use of these C H A P T E R 4 Guidance
links. In many cases, however, information has been repeated from other sections of the report so that this chapter can be more easily used as a stand-alone document. 4.2 Performance Issues Addressed by the Guidance The following notes explain what the more detailed meas- ures described in this guidance are attempting to achieve in overall terms. 4.2.1 Derailment Protection The main causes of derailment covered here are flange climbing derailment and derailment on switches and cross- ings. These can cause any LRV to derail, but the specific type of LFLRV covered by the guidance is more vulnerable. 4.2.2 Wheel and Rail Wear The main causes of wear, associated with this type of vehi- cle, are ⢠High guiding forces caused by poor steering capability, ⢠Constant flange contact on straight track caused by lack of self-centering capability, ⢠Incompatible wheel and rail profiles, and ⢠Misaligned track. LFLRVs using IRWs are intrinsically more prone to wear because of their dynamic performance and sensitivity to external factors. 4.2.3 Ride Quality The vehicle configuration may cause the end sections to pitch. Pitching can be eliminated by design of the articulation and linkages between the sections. There is little room on this design of center truck for extra suspension equipment. 4.2.4 Noise The various sources of noise can be aggravated by the use of center trucks with IRWs. Rubbing flange contact will occur on tangent track. Wheel and rail roughness, caused by wear and so forth can generate a rumbling noise. Rolling noise can be created if the bearing surfaces are not properly maintained. Light contact of the unpowered IRWs on the track may cause corrugations, which create very noisy conditions. On sharp curves, both flange contact and lateral slip of the wheel can occur creating wheel squeal and flanging noise. Noise may also result from poor quality special trackwork. There is less space on this configuration of vehicle to install damping material. These issues can be managed within acceptable limits by a combination of measures, some of which may also relieve the other issues already noted and by solutions that might only be applied locally, such as wayside lubricators on sharp curves or vehicleborne friction conditioners. 4.3 Fundamental Guidance Some issues apply generally or in more than one of the main areas into which the guidance has been split. These are fundamental to the situation being studied (i.e., the intro- duction of a technology to the United States and Canada that has largely been developed elsewhere). The transit systems of other countries have adopted different standards and oper- ate in a different regulatory environment than those of the United States and Canada. As a result, new systems in those countries do not follow the same practice. These basic facts give rise to potential risks that can be mitigated by applying these fundamental principles: ⢠Guideline 1: The vehicle supplier must fully understand the requirements of the transit system and the operating con- text and modify designs accordingly. The transit system must facilitate this by providing all relevant information. ⢠Guideline 2: The transit system must fully understand the effect of anything it specifies and not make requirements that are inappropriate for LFLRV operation (e.g., the sys- tem has put forward âhistoricalâ requirements). ⢠Guideline 3: The infrastructure must be suitable for the type of LFLRV to be used, taking into account features that may not appear in a written specification and may need to be modified to suit. Successful implementation and operation will ultimately depend on all guidelines being followed in all areas. The over- riding guidance is to emphasize the importance of achieving compatible solutions to solve issues where the interface issues are crucial. As mentioned above, this guidance is limited by the scope and resources available for this research program and the comprehensiveness of earlier studies that have been assimi- lated into it. This means that full and accurate application of the guidance would not necessarily mitigate all issues likely to 36 Ref Time period Situation covered A Existing system with existing vehicles B New system with vehicle designs currently available C Short/ Short term medium term Existing system, replacing vehicles with vehicle designs currently available D Medium /long term Existing system, replacing vehicles with ones of a new design E Long term New system with new designs of vehicle Table 4-1. Situations where the guidance will apply.
arise. Application of the guidance will require further work in order to develop optimum vehicle/track performance on spe- cific transit systems. 4.4 Vehicle Specifications 4.4.1 Who Applies These? Technical requirements for vehicles will be specified by the transit system and followed by the vehicle supplier, either based on those provided by the transit system or on their own engineering and commercial strategy. The extent to which the transit system specifies and the supplier designs will vary, according to the type of specification process used, but the overall vehicle standards should not be affected by this as Figure 4-1 shows. Where a performance specification is used, Guideline 1 is particularly important, whereas where a technical specifica- tion is issued, Guideline 2 becomes more significant. 4.4.2 Where Do They Apply? Table 4-2, an extract from Table 4-1, shows the situations in which consideration of vehicle specifications applies (i.e., C, D and E). Situation C will only apply if the existing vehi- cles exactly match, or can be modified to match, the vehicle requirements. In the guidelines that follow in this section, a distinction is made between vehicles being supplied to exist- ing systems and vehicles being supplied to new systems. 4.4.3 Basic Vehicle Configuration The vehicles described here are LRVs with three-section articulated bodies as shown in Figure 4-2. The center section is mounted on its own truck, the âcenter truck,â which is an unpowered trailer truck. The end sections are mounted on individually powered trucks, but part of their mass is also car- ried by the center truck via the articulations. The floor height in the central area of the vehicle is relatively low, so the wheelsets on the center truck do not have solid axle connec- tions but use IRWs. The researchers are therefore assuming that this configuration is included in the vehicle specifications. The remaining guidance in this subsection describes how key ele- ments of this configuration can be specified so as to minimize performance issues. Any basic vehicle configuration must be tested, initially by modeling, to check that it performs satisfac- torily on the system(s) that might use it. 4.4.4 Wheel Profile Table 4-3 lists the main features of a typical wheel profile (Figure 4-3) and shows how each one influences the key per- formance criteria. The profile must be designed to give run- ning stability at speed and must be optimized for the conditions of the system, including speeds and ratio of sharp curves to tangent track. Using the same profiles on all vehicles on a system is desir- able; introducing new profiles, either on new or existing vehi- cles, needs to be carefully programmed in order to allow a smooth transition. âRailwayâ type profiles may be used but this choice rules out any flange tip running and it may prove difficult to main- tain the rail sections in the street, whereas transit wheel pro- files can use grooved rail, which is simple to maintain in that it only requires grinding horizontally. The use of wheel profiles that match the rail profile mini- mizes wear (however, see Section 4.9.4. as well). Continuously evolving contact points and contact angles reduce noise and wear and are preferable to two-point contact, which should be avoided. Contact in the flange root area should minimize noise and wear. The use of a large flange root radius between the tread and the flange can avoid the need for steep tread slopes (such as 1 in 20), which may be less suitable for light transit, but at the same time reduce flange contact. The profile should not encourage a rapid change of contact points, which will create jolts and damage wearing surfaces. 37 Figure 4-1. Variation in procurement methods. Ref Situation covered C Existing system, replacing vehicles with vehicle designs currently available D Existing system, replacing vehicles with ones of a new design E New system with new designs of vehicle Table 4-2. Situations where considerations of vehicle specifications apply. Figure 4-2. Configuration of the LFLRVs used in the United States and Canada.
On sharp curves, the wheel profile âfootprint,â(i.e., a hori- zontal section through the flange at rail level) needs to be con- sidered. Clearance needs to be considered in three dimensions, rather than just the two associated with a verti- cal cross section. Developing a suitable wheel profile for a vehicle is an issue of balancing the following main requirements: ⢠Satisfactory guidance on all types of track, ⢠Safety against derailment, ⢠Ride quality, ⢠Minimizing contact stress and avoiding rolling contact fatigue, ⢠Minimizing wear, and ⢠Minimizing the requirement for changes to rail profiles and wheel profiles on existing vehicles. Flange-tip running is a standard practice on street running transit systems. The tip of the flange is flat so that the wheels can run on a flat surface in the frog casting rather than rely- ing on the tread, which will drop significantly in the gap required on sharp switches. The angle of switch at which flange-tip running becomes necessary depends on wheel width. Because flange-tip running tends to cause more wear and noise, it should only be used when essential, especially where LFLRVs are in use, where the noise will be more apparent. The need for flange-tip running can be avoided if sharp angle switches and crossings are not used, but the use of sharp angle crossings may be unduly restrictive on light rail transit (LRT) system design in some cases. 4.4.5 Lubrication Table 4-4 summarizes the types of lubrication system avail- able. The choice of lubrication system depends on local con- ditions (e.g., a system that is largely straight with one sharp curve may use a track-based solution at that location only, whereas a system characterized by many sharp curves may equip some or all the fleet with vehicle-mounted lubrication systems). LFLRVs require flange lubrication for the center truck because of the increased incidence of flange contact and higher lateral forces compared with high-floor cars. 4.4.6 Wheel Parallelism The design of the center truck must specify sufficiently close tolerances to ensure that the parallelism of the IRWs is maintained within close limits. In Germany, the parallelism of the axles in a truck should be within 1.2 mm (0.05 inches) measured at the wheel. One German system that has been using LFLRVs for some years found that halving this figure to 0.6 mm (0.025 inches) for the âtheoreticalâaxles of IRWs gave a satisfactory performance. 4.4.7 Vertical Suspension Stiffness The limited space available for primary suspension within the design of a low-floor truck creates a challenge for the designer in achieving sufficient flexibility to accommodate track twist. Despite this, most solutions successfully use a conventional arrangement of a rigid frame and primary sus- pension. It is possible to save space by reducing the flexibility of the suspension and providing a truck frame that is articu- lated in the twisting sense. Any such arrangement must, how- ever, ensure that parallelism of the wheelsets is maintained. 4.4.8 Vehicle Articulation Design The articulation design encompasses the mechanical arrangement by which the end sections, the center truck, and the center section are attached together. Various designs are possible with no intrinsic advantage of one arrangement over another. However, all designs must address the following basic requirements: ⢠Safety Against Derailment. The design must not generate excessive lateral forces between the wheel and rail and must 38 Profile feature Influences Tread slope and shape Ride, guidance, wear, and noise Flange angle Derailment protection, passage through S&C Toe radius Switch safety Toe shape Flange running ability Flange height Derailment/depth of grooves Blend radius Guard rail effectiveness Flange root radius Flange wear (especially on IRW) Flange thickness Toe radius/blend radius, wear allowance. Table 4-3. The purpose of the features of a wheel profile. Figure 4-3. Main features of a wheel profile.
be capable of negotiating all track features without leading to wheel unloading. Lateral forces are typically controlled using a pair of dampers at roof level to control center sec- tion yaw. These only need be provided at one end of the center section. ⢠Wheel Wear And Noise Generation. The design must ensure that the alignment of the center section is main- tained as close to tangential to the rails as possible, in order to minimize noise and wear generated by flange contact. To achieve this, the alignment tolerances must be maintained as closely as possible, and parasitic noises (e.g., such as those arising from dampers) must be minimized. ⢠Ride. Pitching of the short center section must be con- trolled. Typically, this requires the use of roof linkages. Alternatively, the center section can be fixed relative to one end-section and only allowed to pitch relative to the other. A single damper on the center line, which only reacts to sharp accelerations or decelerations, may be suf- ficient. Relative roll between sections must also be con- trolled, either by linkages or by the design of the articulation pivots. 4.4.9 Summary of the Proposed Guidelines for Basic Vehicle Parameters Table 4-5 summarizes the guidelines proposed for vehicle parameters by heading. The final column gives the reference for background information on why the suggestion is made. It is only possible to give some limiting values; actual values need to be determined for each design by the use of modeling tech- niques. These guidelines cover the main parameters identified 39 Location to lubricate Vehicle mounted Track mounted Flange/gauge face of rail Grease spray sticks Grease application by hand or an automatic Grease spray sticks Grease application by hand Friction modifier sticks Friction modifier application by automatic system Wheel back/restraining rails Tread-rail head system Table 4-4. Types of lubrication. Parameter Existing systems New systems Cross reference Floor height above rail above the center truck. About 350/355 mm (133/4-14 inches) unless there are good reasons for using another height and never less than 290 mm (111/2 inches) About 350/355 mm (133/4-14 inches) and not less than 290 mm (11 1/2 inches) Center truck wheel diameter (Minimum) 26 inches (660 mm) 550 mm (215/8 inches) Section 3.6.1 Center truck wheelbase 1800-1900 mm (71-75 inches) Section 3.6.1 Wheel gauge (see note 1) To be determined based on giving a minimum clearance of 5 to 7 mm (0.2-0.3 inches) to the existing track under all conditions Nominal track gauge less 9 mm (3/8 inch) Section 3.6.5 Wheel width To be determined based on track geometry Preferably 5.25 inches (133 mm) or 4 inches (102 mm) if flange tip running is used throughout Section 3.6.2 Wheel taper See note 2 See note 2 Section 3.6.2 Wheel flange height 24 mm (0.95 inches) with flange tip running, 20 mm (0.8 inches) otherwise 22 mm (0.87 inches) with flange tip running, 20 mm (0.8 inches) otherwise Section 3.6.2 Flange angle To suit rail profile and similar to other cars that will continue in use on the system 72o minimum. 75o maximum (the latter for lines with sharper curves and switches) Section 3.6.2 Back-to-back wheel dimension To be determined from preceding figures and based on track geometry and an appropriate flange width Wheel gauge less twice the appropriate flange thickness Table 4-5. Summary of proposed guidelines.
in this research as influencing LFLRV performance signifi- cantly. The guidelines all apply to the center truck. Note 1: Wheel gauge is the distance between the contact areas on the rail sides of the flanges on a pair of wheels. It is measured at a defined gauge line height for new wheels âwheelset.â The figures shown apply to the center truck. Note 2: The wheel taper should be between 1 in 20 and 1 in 40. The actual value should be determined by analysis and will relate to the type of rail used and its inclination. A variable taper will reduce the risk of two-point contact and provide better steering and possibly give better results. The objective is to keep contact at the rail center. The selection of actual parameters can be based on a âdecision treeâ approach in order to develop an optimized solution. 4.5 Vehicle Selection Issues The transit system must check that the vehicles being sup- plied meet the requirements stated in Section 4.4 as part of a structured vehicle acceptance process. The following steps are envisaged: ⢠The supplier provides a response to the request for a proposal that included the transit systemâs specification.The supplierâs response should include the supplierâs own specifications, drawings,and other data.The transit systemâs assessor should scrutinize this information and carry out any necessary cal- culations and investigations to ensure that the requirements are met.This should involve requests for further information from the supplier as necessary. The process should also involve modeling vehicle performance, using an appropriate software package, and replicating the actual track conditions as closely as possible, although there may not always be suffi- cient data available to do this thoroughly. The modeling should either be carried out by the transit authority or by the supplier or the supplierâs agent. In the latter case, the results should be certified or checked by an independent body act- ing on behalf of the transit authority. ⢠During the design and construction process, the supplier may wish to modify the vehicle design. In this case, each modification should be acceptance-tested by the transit authority according to the guidance in Section 4.4 and using the dynamic modeling package if appropriate. ⢠When the first vehicle is ready to be delivered, the supplier should certify that it now meets the agreed specifications and vehicle acceptance tests should take place. These tests should take place at either the supplierâs own premises or elsewhere as appropriate. The main stages, in relation to the issues described in Section 4.4, will be ⢠A visual check to see that the vehicle has all the features expected and that they are correctly assembled; ⢠A static measurement check, including use of wheel pro- file measuring gauges; ⢠A static loading test to check that the suspension char- acteristics are as expected; ⢠Dynamic running tests to ensure that the vehicle ride meets the performance requirements under a range of loading conditions, including noise measurements both inside and outside of the vehicle; and ⢠Checks on the condition of the wheel running surface and on the track at vulnerable locations (e.g., sharp curves and switches) to ensure that excessive wear is not occurring. Such checks will be made throughout an extended period of testing in service before the vehicles are finally accepted. This process constitutes âtype testing.â Acceptance tests shall also be arranged for subsequent deliveries of the same type and, as a minimum, the supplier should certify that each vehicle has been checked to ensure that the key parameters comply with those of the vehicle that was thoroughly tested. 4.6 Vehicle Maintenance Guidelines 4.6.1 Who Applies These? Maintenance of vehicles is often carried out by the transit system, although it is quite common for it to be performed under a maintenance contract by the supplier or another agency. It is also usual for vehicle maintenance to be the responsibility of the supplier until the completion of an acceptance process. In these circumstances, either the transit system must fully understand the issues associated with maintaining what may be a vehicle type that has not operated on the system before, or the contracted supplier or agency must be fully familiar with the âpeculiaritiesâ of the system and the way it is operated. Part of the process involves the supply of information by the supplier so that staff are aware of maintenance require- ments. Part of the responsibility will, therefore, rest with the supplier, even where they are not involved in subsequent maintenance activity. It is vital that suppliers provide infor- mation as part of their contract, in the form of manuals, training, and so forth, that take into account the level of familiarity of the maintenance staff with their vehicles. This will avoid the serious issues that can arise when a supplier delivers a vehicle to a new market that is unfamiliar with the technology. 4.6.2 Where Do They Apply? Vehicle maintenance guidelines will apply in the situa- tions (A to E) described in Section 4.1. In Situation A, it may be necessary to implement some of these suggestions retroactively. 40
4.6.3 Process It is suggested that vehicle maintenance is based on the fol- lowing principles: ⢠Provision of high-quality technical manuals, ⢠Training of staff, ⢠Scheduled preventive maintenance, ⢠Timely corrective action, and ⢠Good-quality maintenance records. These principles will apply generally, but are even more important in ensuring that performance issues associated with LFLRVs are minimized. Provision of High-Quality Technical Manuals There have been cases where suppliers have provided inadequate technical manuals with incomprehensible draw- ings, incomplete sections, text in foreign languages, text lifted from subcontractor manuals without editing, and so forth. The contract for vehicle supply should include the provision of adequate technical manuals, with procedures for fault finding, preventative and corrective maintenance, overhaul, and so forth. The manuals should also include illustrated parts lists. The format of the manuals should include photo- graphs, diagrams and other material to readily identify com- ponents, and how testing, dismantling and re-assembly takes place. They should be divided into sections to cover different types of maintenance (e.g., electrical, mechanical, and diag- nostic). Manuals should be supplied in both printed and digital format. The manuals only need be provided where the suppliers are not carrying out maintenance; this applies to compo- nents as well as vehicles as a whole. So for example if the cen- ter trucks are to be maintained by the supplier, the manual should only cover how they are removed, replaced, and tested. The maintainer should check and approve the manuals as part of the vehicle acceptance process and the supplierâs con- tract should ensure that the maintainer makes any appropri- ate changes. The maintainer, where this is not the supplier, should con- sider incorporating the manuals into its own maintenance documentation. This has several advantages: ⢠The manuals can be simplified to cover only the require- ments of the transit system. ⢠Any special requirements of the system can be highlighted. ⢠The maintenance schedules (see below) can be incorpo- rated. ⢠Experience can be incorporated. ⢠The user should normally only refer to one document, which is more convenient, saves time, and avoids poten- tially serious confusion. Training of Staff Maintenance staff require training to maintain LFLRVs. Where the maintenance is not to be carried out by the sup- plier, the training should also be a part of the vehicle supply contract and its successful completion should be part of the vehicle acceptance process. The training needs to be such that it will allow some of the staff trained to train other new staff subsequently. The maintainer has a responsibility to ensure that training is ongoing. Training will normally be based on the material in the manuals and include both classroom and on-vehicle training with fault finding and other exercises. At the conclusion of any training, trainees should be tested so as to ensure that they meet the required standard and their ongoing perform- ance should be monitored. If any maintenance procedures change because of experience, new components, and so forth, refresher courses will be necessary. Scheduled Preventive Maintenance LFLRV performance will partly depend on maintaining key center truck parameters within relatively tight toler- ances; therefore, vehicles must be monitored as part of a scheduled preventive maintenance program. Tolerances and other requirements, as listed in Table 4-6 and included in the supplierâs manuals, need to be checked. Initially, checking should be performed relatively frequently until âpatternsâ are discerned and the supplierâs recommenda- tions for periodic inspection can either then be adopted or modified. The equipment and techniques used for taking critical measurements must do so accurately and properly gage tolerances. Timely Corrective Action Where an issue is identified or emerges it is essential that the vehicle does not remain in service if this might cause dam- age, be dangerous or initiate performance issues. Good-Quality Maintenance Records Records need to be kept for each vehicle, each truck, and each component on the center truck and for other key com- ponents associated with LFLRV technology (e.g., roof- mounted linkages and dampers). The records should show measurements taken during programmed inspections and after major maintenance work and overhaul has taken place. 41
4.6.4 Maintenance Tolerances Vehicles are designed to manufacturing tolerances but may be maintained to different tolerances. Also, dimensions will be allowed to vary within operating tolerances before main- tenance or corrective action occurs. The maintenance manuals should include tolerances for all the features shown in Table 4-6 that are associated with the performance of the center trucks on LFLRVs; these are derived from the standards mentioned in Section 4.4, or are typical of tolerances in use in the industry. They are not exhaustive. Where actual tolerances are shown, these will only apply for vehicles that also conform to the recommendations for new systems specified in Section 4.4. In all other cases, tol- erances must be developed based on the principles outlined in this guidance and described elsewhere in the report. Avoid creating rough wheel surfaces because of wheel truingârough wheel surfaces increase derailment risks, especially on LFLRV center trucks. A surface finish of N8 (125 μinch) should be achieved. 4.7 Vehicle Modification Circumstances can arise where either the supplier or the transit system undertakes modifications to vehicles. Where vehicles are transferred between systems, it may be necessary to make modifications because of different track geometry or other reasons. In all these cases the modification must be seen as a design change and both the modification itself and any other features of the vehicle that may be altered as a result must go through the same processes as would be associated with a new design, including ⢠Application of the fundamental guidance Guidelines 1 and 2 (see Section 4.3); ⢠Application of the proposed specifications (see Section 4.4); ⢠Acceptance process (see Section 4.5); and ⢠Revised maintenance standards with new manuals, train- ing and tolerances (see Section 4.6). 4.8 Future Vehicle Design This chapter can also be used as guidance on the overall design of LFLRV most likely to give trouble-free performance on U.S. and Canadian transit systems. This assumes that the design is limited to the scope of the research (i.e., LFLRVs having an unpowered center truck with IRWs), but it needs to be re- emphasized that other types of LFLRV may also be a possibility. The guidance will apply to the two âlong-termâ situations D and E of Table 4-1 (Table 4-7). In these cases, the guidance shown in Table 4-5 will apply, but it is possible to identify a standard set of parameters that may well have a ready market, especially for Situation E, that would have the following fea- tures. Option A is suitable where flange tip running exists on most switches and crossings on the system and Option B where it does not. The suggested parameters are Floor height: 350 mm (133/4 inches) Center truck wheel diameter: 660 mm (26 inches) Center truck wheelbase: 1800 mm (5 feet 11 inches) Wheel gauge: 1,426 mm (56.14 inches) Wheel width: Option A 4 inches (102 mm) Option B 5.25 inches (133 mm) Wheel taper: Variable taper. Wheel flange height: Option A 22 mm (0.87 inches) Option B 20 mm (0.79 inches) Flange angle: Variable between 72o and 75o Back-to-back wheel dimension: Depends on flange thickness These key critical interface parameters are associated with center truck design based on the research carried out and assume that the equivalent infrastructure standards also apply. 42 Parameter Tolerance Cross reference Difference in wheel diameter between wheels on the truck Within 1/16 inch (1.6mm) Section 3.6.1 Wheel wear on tread before scrapping Depends on wheel and rail profiles Wheel wear on flange before scrapping Depends on wheel and rail profiles Wheel gauge +0.04 inches (+1 mm) Wheel taper +0.5o Flange height Minimum 0.75 inches (18 mm) Section 3.6.2 Flange angle +3o, -2o Section 3.6.2 Wheel back-to-back dimension +0.04 inches (+1mm) Axle parallelism 0.6 mm (0.025 inches) Section 3.6.1 Table 4-6. Features to be included in maintenance manuals. Ref Situation covered D Existing system, replacing vehicles with ones to a new design E New system with new designs of vehicle Table 4-7. Situations where future vehicle design will apply.
4.9 Infrastructure Guidelines 4.9.1 Application One of three situations will apply as shown in Table 4-8. The third situation is quite common on older European sys- tems where, although LFLRVs have been introduced, LFLRVs are often confined to certain routes until other routes are modified. The split in the level of detail in the specification between the transit system and the infrastructure supplier, in Situations 2 and 3, will vary in a similar way to that for vehi- cle specifications as discussed in Section 4.4. The fundamen- tal Guidelines 2 and 3 (see Section 4.3) apply to infrastructure and are essential to ensure trouble-free performance. Infra- structure standards will apply in all the scenarios described in Table 4-1. 4.9.2 Track Geometry Standards Table 4-9 shows the track geometry guidelines suggested for existing and new systems using LFLRVs. It is very impor- tant to get the gauge and position of restraining rail correct on curves. 4.9.3 Track Guidelines New systems should consider using 115 RE rail. For embedded track, the matching rail is either Ri59/13 or Ri59N grooved rail or 115 RE with a formed groove along- side. 115 RE rail should be inclined at 1 in 40âthis will match the profile of RI59 where the latter is laid without any inclination. In some cases, these sections will not be appro- priate, but care needs to be taken to select a rail section that matches these sufficiently well so that wheel profiles can be modified if necessary. Older systems should replace their rail with these sections when rail becomes due for renewal and should replace it when introducing LFLRVs if the business case makes sense. Otherwise they should continue with the rail sections in use. The track base must remain as level and twist free as possi- ble so the specifications for new lines should include features to make the track maintain its alignment. Older track should be upgraded to this guideline or operated at reduced speed. Where ballast is used, ballast shoulders should be created so as to hold the track against lateral movement. Heavier grade ballast will help maintain track alignment. 4.9.4 Wheel-Rail Interface Guidelines The wheel-rail interface must be compatible in all situa- tions. The wheel and rail profile should be such that there is contact over the designed contact area on the wheel tread and the wheel flange. At the same time, contact bands must not be too wide because such bands might be a cause of rolling con- tact fatigue (see Section 3.6.2). 4.9.5 Switches and Crossings One of the main objectives of specifying features of switches and crossings when LFLRVs are operated is to minimize derailment risks associated with IRWs on the types of center truck used. This can be achieved by a smooth passage and reducing the freedom for wheels to take a wrong path. The following guidance is based on the research findings and an earlier TCRP report (1). In this case we need to recon- sider Table 4-1. In Situations A, C, and D, the switches and crossings will already exist and they may or may not be suit- able. As a minimum, they should be modified so as to allow LFLRVs to operate safely. It is difficult to generalize what will be required to do this because of the possible variations in track geometry and vehicle, but one might ⢠Change the type of switch, ⢠Change the ânumberâ of the switch to give a less acute switch angle, ⢠Provide more guard rails, ⢠Improve the embedding of the switchblades into the run- ning rails, and/or ⢠Provide cover guards (house tops). Table 4-10 shows guidance for switches and crossings in Situations B and E. In Situation B it is still difficult to gener- alize in all areas because of variations in vehicle parameters. In Situation E, however, one can assume that the vehicles and track will conform to the guidance given so far in these guid- ance notes. 43 Situation Description Who sets and applies the standards 1 An existing system that is introducing LFLRVs. Transit system 2 A new system that will use LFLRVs. Transit system/infrastructure supplier 3 An existing system that will have new extensions that will use LFLRVs but where the standards need to allow for compatibility with existing routes. Transit system/infrastructure supplier Table 4-8. Situations where infrastructure standards will apply.
44 Feature Existing systems New systems Note Nominal track gauge As existing unless a business case can be made for conversion to 56.5 inches (1,435 mm.) 56.5 inches/1435 mm (or close equivalent). Use of standard gauge gives maximum choice of supplier. Tangent track gauge As existing but modify if appropriate. Based on nominal track gauge, wheel profile, and new build tolerances. See Section 3.6.5. Minimum curve radius As existing but try to avoid regular use of unusually sharp curves if possible. 82 feet (25 m). For each curve use as large a radius as practical, especially on frequently used track. Gauge widening on tight radius curves As existing but modify if appropriate. None. See Section 3.6.5. Minimum tangent track between curves As existing but modify if appropriate. Length = 0.35V where V = operating speed (mph), or 66 yards, whichever is greater. Transition curves should be used wherever possible. Vertical curvature As existing. Appropriate for vehicle geometry. Combinations of sharp horizontal and vertical curves are to be avoided. Rail inclination As existing. Depends on rail type. Flangeway clearance As existing. Minimum 0.2 inches (5 mm), ideally 0.28-0.31 inches (7-9 mm) See Section 3.6.5. Where should restraining rail be provided? Conform to existing practice. Apply U.S. Standard. Flangeway width Existing. 111/16 7/8 inch (42 mm) preferred unless unsuitable. Flangeway depth Existing. 1 inch (47 mm) preferred unless unsuitable. Flangeway dimensions correspond to those of RI59 rail. Table 4-9. Suggested track geometry guidelines. Feature Situation B (Existing vehicles) Situation E (New vehicles) Type of switch operation Flexible switch rails rather than pivoting switchblades; swing nose frogs are ideal. Stock rail contact Make use of undercut blades (e.g. Samson switches) Embedment Make use of elastomer to reduce noise Guard rails Adjustable so that they can be set accurately. Switch rail tip design Adapt to suit vehicles Design to avoid flange angle issues Fully guarded switches Provide if necessary at vulnerable locations Avoid need by good overall system design House tops Provide if necessary at vulnerable locations Avoid need by good overall system design Flangeway As constant as possible, acting like the plain line situation. Flangeway clearances Minimum 11/2 inches (38 mm) wide. 13/8 - 11/2 inches (35-38 mm) deep (U.S. Standard) Minimum size As existing but improve if possible. #10. #8 in crossovers, #6 in yards. Table 4-10. Guidance on switches and crossings.
4.9.6 Lubrication Trackside lubrication is an appropriate way to reduce noise and wear on curves and help minimize the risk of derailment on switches and crossings; however, it should only be used on sections of track where such issues arise. 4.10 Operation of LFLRVs The following guidelines are for any U.S. or Canadian sys- tem introducing LFLRVs to minimize performance issues: ⢠Staff training should include issues peculiar to LFLRV operation, including an appreciation of the risks of not adopting changed practices. This training should include operators, vehicle and track maintenance staff, and super- visory staff. ⢠Procedures should be in place in order to recognize and deal with the early symptoms of performance issues, (e.g., wheel and rail wear and noise), and to allow man- agement to take early corrective action while minimizing disruption. ⢠Operators should avoid vehicle jerking and maintain con- stant speed on curves, only accelerating when the curve has passed. This is particularly important as a means of achiev- ing ride comfort on LFLRVs. ⢠If LFLRVs need to operate at slower speeds than other vehi- cles in the fleet, the operators need to be fully aware of this. 4.11 Infrastructure Maintenance Standards 4.11.1 Who Applies These? Maintenance of track is often carried out by the transit sys- tem, although it is quite common for it to be performed under a maintenance contract or, in the case of new infra- structure, by the supplier. In these circumstances, the main- tainer must fully understand the issues associated with maintaining track in a suitable condition for the LFLRVs operated on it. Track standards assumed by the vehicle sup- plier when vehicles were supplied need to be followed subse- quently or problems will occur. A process for managing the interface between vehicles and track at the contract stage should cover this. 4.11.2 Where Do They Apply? Infrastructure maintenance guidelines will apply in the sit- uations (A to E) described in Section 4.1. In Situations A, C, and D, it may be necessary to implement some of these rec- ommendations retroactively. 4.11.3 Process The researchers recommend that infrastructure mainte- nance be based on the following principles: ⢠Provision of maintenance manuals, ⢠Training of staff, ⢠Use of adequate tools and equipment, ⢠Scheduled preventive maintenance, ⢠Timely corrective action, ⢠Good-quality maintenance records, and ⢠Maintenance tolerances. These principles apply generally but are even more important in minimizing performance issues associated with LFLRVs. Provision of Maintenance Manuals Using good-quality infrastructure maintenance manuals can overcome many issues.Each system needs to provide such man- uals so as to address system-specific situations. For example, even though track workers may have all the information and training needed to determine what needs to be done and to cal- culate the tolerances that apply, workers are much more likely to do the work properly if all requirements are set down in one place in an easy-to-use document.A consistent approach,so that everyone involved in track maintenance understands their roles and responsibilities, is also needed. The act of creating an infra- structure maintenance manual ensures that the transit author- ity anticipates issues that might cause issues and manages them. Where the maintainer is not the transit authority, the lat- ter should monitor the process sufficiently so as to ensure that the performance requirements are being met in an optimized way (e.g., the transit system has not observed the guidelines and, as a result, its vehicles are suffering excessive wheel wear). An independent body may perform this audit. Manuals should be updated periodically as experience is gained and should incorporate clear schedules for periodic maintenance and procedures for dealing with different levels of issues that might require corrective action. Training of Staff Maintenance staff need training to maintain infrastructure to the new guidelines that might be required for LFLRVs. Such training should be part of the training normally pro- vided to maintenance staff, rather than as a separate course. Any maintenance contract should require the maintainer to provide this training both for existing staff and for new staff. Training will generally be based on the material in the manuals and include both classroom and on-track training. At the end of any training, trainees should be tested to ensure 45
that they meet the required standard and their ongoing per- formance should be monitored. If any maintenance proce- dures change because of experience, new practice, and so forth, refresher courses will be necessary. Operators should be trained to report faults that they detect when driving vehicles in regular service, because this an important source of feedback on condition. Tools and Test Equipment The tools and test equipment needed to meet the mini- mum requirements of this guidance are as follows: ⢠Profile measurement systems, ⢠Track measurement cars, and ⢠âMine sweepersâ to detect track anomalies. Scheduled Preventive Maintenance LFLRV performance will depend partly on maintaining key track parameters within relatively tight tolerances; there- fore, these tolerances must be monitored as part of a sched- uled preventive maintenance program. The key parameters to be checked include rail profile and alignment, switches and crossings dimensions (including gauge face wear), and avail- ability of trackside lubrication. The periodicity and methods of inspection should be determined and incorporated in the infrastructure maintenance manual. Also, faults should be detected during the course of scheduled service running. Timely Corrective Action Where an issue is identified or emerges, action must be taken to avoid accidents, damage, or objectionable performance issues. The seriousness of the issue should be determined and then graded on a scale of action that might range from no action but correct by the next periodic inspection to situations that might require operational restrictions to a complete stoppage. Good-Quality Maintenance Records Records need to be kept for the maintenance work carried out on the track and should consist of a linear record of each section of the route and for each infrastructure item (e.g., switches), showing details of components, measurements taken, inspections made, and work carried out. These records should be revised whenever work takes place and be available to everyone who needs access to them. Maintenance Tolerances The maintenance manual should include maintenance toler- ances for all the features of the infrastructure where LFLRVs are operated. Some possible tolerances are shown in Table 4-11 as 46 Parameter Tolerance Note Track gauge + inch, - inch (+9.5 mm, -6 mm) from design Example of a standard that has been used in the U.S. where LFLRVs are in use. Track wear Top wear 25 mm (0.975 inch), side wear 20 mm (13/16 3/8 1/4 1/4 inch). German standard, which accommodates IRWs but is not unduly harsh in the U.S. Horizontal alignment APTA 8.3 Table 5 See Section 3.6.6 Lateral alignment APTA 8.4 Table 6 Track twist APTA 8.4 Table 6 Super-elevation APTA 8.4 Table 6 A check is needed that the lateral alignment variations provide sufficient clearances for LFLRVs. Cross level Not more than 1 inches (32 mm) variation in 62 ft (8.9 m) length. Tighter than APTA 8.4 Table 6 Track structure APTA 9 and 1?3.5 Standards must be developed so that the requirements listed above are met. Rail-end mismatch None should exist. Welded rail should always be used. Restraining rail guard face gage 5 mm (0.2 inch) variation Tighter than APTA 11.2 Table 12. Minimum flangeway in S&C This may be less than the 1 inches (38mm) in APTA 12.1.2 IRWs are an "exception," see APTA 1.3 Flangeway depth APTA 12.3.1 and 13.4.2 apply. Condition of S&C It may be necessary to adopt tighter standards than APTA recommends. See also APTA 13.7 Gauge face wear angle +3o to match wheel limits 1/4 Table 4-11. Suggested maintenance tolerances.
an indication of how tight they may need to be, but each system should derive tolerances for its own conditions. This is not a list of all the features that should be included, but concentrates on those features especially important for operating the type of LFLRV being studied. These are derived from the guidelines mentioned in Sections 4.9.2 through 4.9.5. Where actual toler- ances are shown, these will only apply to vehicles that also con- form to the guidelines for new track specified in those sections. The researchers assume that the basis for the systemâs mainte- nance standards are APTAâs Standard for Rail Transit Track Inspection and Maintenance, referred to as âAPTAâ in the table. 4.12 Infrastructure Modification Circumstances can arise where the transit system modifies track. Modifications might include removing redundant fea- tures to allow easing of curves, eliminating problematic fea- tures, and so forth. Modifications should never âworsenâ the standards described in the preceding paragraphs. Modifica- tion may require the addition of requirements that may appear âworseâ (e.g., tighter radii because of introducing street running to a system previously confined to reserved track). In all these cases, the modification must go through the following processes: ⢠Application of the fundamental guidance provided in Guidelines 2 and 3 (see Section 4.3); ⢠Application of the proposed guidelines (see Section 4.9); ⢠Acceptance; and ⢠Revised maintenance guidelines with new manuals, train- ing, and tolerances (see Section 4.11). 4.13 Best Practice for System Design 4.13.1 Basics This section considers the situation likely to arise in the future where a totally new system is planned that is not con- strained by any existing design decisions or technology and will not need to link with an existing one. It will only be con- strained by federal, state, and other regulations. Basically, four types of transit system might use LFLRVs: 1. Street running using embedded rail; 2. Reserved track (e.g., using flat bottom rail, cross ties, and ballast or direct fixation); 3. Transit sharing railroad tracks; and 4. Combinations of these. LFLRVs can operate on all these, and this will probably continue. There is no ârightâsolution for transit system types; the choice depends on local circumstances. For an entirely new system, the choice of LFLRV and guidelines to be fol- lowed will be influenced by the type of system. It is not nec- essary to have an âoptimumâ solution that will suit any type of systemâdoing this may add unnecessary cost and inflexi- bility to new transit networks. The next fundamental issue is the choice of floor height. In the future, most entirely new transit systems may want to use low-floor vehicles in order to meet ADA requirements. An exception may be Type 2 systems that might economically use high platforms with high-floor vehicles and gain level access throughout. If low-floor vehicles are selected, basically, two choices existâpartial low-floor (PLF), which includes the type of vehicle being considered in this study, and 100-percent low-floor vehicles. The issue of adopting 100-percent low-floor cars was con- sidered in TCRP Report 2 (Chapter 3). The study concluded that introduction into the United States and Canada on entirely new systems might prove difficult because ⢠New systems might not wish to assume liability for speci- fying lower buff loads, even though no technical reason was identified why this cannot be done. ⢠100-percent low-floor designs might not meet stringent U.S. and Canadian fire standards (ASTM E-119 was specif- ically cited). The buff loads traditionally applied in the United States are derived from the â2 gâ formula (i.e., the vehicle should sustain an end loading equivalent to twice its own mass). This has not been the practice in Europe and, as a result, U.S. and Canadian LRVs tend to have heavier structures than their European counterparts. This is not always the caseâ New Jersey has used a 1-1.1 g formula. On the other hand, some states (e.g., California) have regulated to the 2 g for- mula (2). TCRP Report 2 observed that U.S. systems tended to use higher speeds but many European systems are now operating at equivalent and higher speeds without the higher buff loads. The buff load issue is a definite restriction for Type 3 systems, or Type 4 systems that include any Type 3 track. However, an initiative is taking place to reconsider the FRA position about buff load requirements for joint use tracks. Ten years on from the publication of TCRP Report 2, greater availability and worldwide experience of 100-percent low-floor operation will begin to outweigh the liability issue. The researchers also suggest that the fire issue be considered as a possible future TCRP research activity, taking into account, among other features, ⢠The environment of transit operations using 100-percent low-floor cars, including the extent of tunnels; 47
⢠The sources of fire under a low floor compared with a high floor; and ⢠Recent standards developed in Europe for fire safety on all types of rail systems, including streetcar and light rail systems. Although the guidance that follows refers only to PLF cars, some of these types may also be affected by the issues mentioned above that have stopped the introduction of 100- percent low-floor cars. 4.13.2 Who Should Apply This Guidance? This section of guidance is important to all the organi- zations and individuals noted in Section 4.1. In particular modifications to track should be of interest to their long- term strategies. Modifications to track will strongly influence ⢠Plans for future transit systems, ⢠Product development for the U.S. and Canadian market, and ⢠Changes in the regulatory framework. 4.13.3 Where Will It Apply? By definition it can only apply to Situation E in Table 4-1 (i.e., long-term new system applications with new designs of vehicle). 4.13.4 Basic Vehicle Configuration The earlier guidance in this document has assumed the specific type of PLF LRV being studied in this research [i.e., one that has three sections, the center section mounted on a center truck with IRWs (see Section 4.4.3)]. However, other types are possible: ⢠A two-section vehicle with floating articulation and an independent wheel bogie under one of the body sections. Because this arrangement has fewer degrees of freedom, it may offer better dynamic performance than the three- section type under study. Examples are the Leipzig Leoliner design and the LF2000 in Dessau. ⢠As above but small-wheel solid axle trailer bogie under one of the sections. Examples are the Geneva and St. Etienne Be4/6 designs. ⢠Cars with all-conventional bogies, floating articulations, and low-floor areas between bogies. Examples are the Sheffield GT8 and Zurich Forchbahn cars. ⢠Cars with all-conventional Jakobs bogies and lowered floor areas between. A European example with low-floor center sections is the Basel Be4/8. ⢠Low-floor trailer cars using small wheels and IRW trucks. This appears to be an outdated concept. Examples exist in Rostock and Leipzig. Some vehicles have been built using EEF wheelsets but, fol- lowing the difficulties experienced with this type, no products are available based on this concept. Given that the researchers did not consider these types of vehicle, no guidance specific to them is given in the notes that follow. It is assumed that systems will be using the center truck type. One area of future research could be to see if using these other types would offer advantages in the U.S. and Canadian context. If the issues listed in Section 4.13.1 concerning the introduction of 100-percent low-floor vehicles were addressed, this might influence future configurations and design of PLF types as well. 4.13.5 Infrastructure Guidelines The track geometry standards listed under ânew systemsâ in Section 4.9.2 would apply. New systems should consider using 115 RE rail. For embedded track, a matching grooved rail is RI59/13 or RI59N, although it is also possible to use 115 RE with a formed groove alongside. Specifications for new lines should include features to make the track as rigid as practical. The wheel-rail interface issues discussed in Section 4.9.4 will apply. The table column, Situation E (New vehicles), in Table 4-10 will apply. 4.13.6 Vehicle Specifications Section 4.8 will apply, but will need to be reviewed for a Type 3 (Joint transit/railroad) application and may only apply if Section 14.13.5 is fully applied. 4.13.7 Other Guidelines The following sections will also apply in full to this situation: ⢠4.5 Vehicle selection issues, ⢠4.6. Vehicle maintenance guidelines, ⢠4.7. Vehicle modification, ⢠4.10. Operation of LFLRVs, ⢠4.11. Infrastructure maintenance standards, and ⢠4.12. Infrastructure modification. Although these are not system design issues as such, the sys- tem design needs to consider that they should be in place. 48