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Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations (2005)

Chapter: Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations

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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
×
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Suggested Citation:"Appendix A - Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations." National Academies of Sciences, Engineering, and Medicine. 2005. Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations. Washington, DC: The National Academies Press. doi: 10.17226/13841.
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A-1 APPENDIX A: Effect of Wheel/Rail Profiles and Wheel/Rail Interaction on System Performance and Maintenance in Transit Operations

SUMMARY The research team performed a survey of representative transit systems to identify the common problems and concerns related to wheel/rail profiles in transit operations. This survey was conducted as part of Phase I of this project to develop wheel/rail pro- file optimization technology and flange climb criteria. The research team conducted onsite surveys at six representative transit systems that involve both light rail and rapid transit operations to collect information related to wheel/rail profiles and wheel/rail interactions. Several vehicle maintenance shops and track sites were visited to observe current wheel/rail profile related practices and prob- lems. Summaries of the information from five of the systems visited are included in the Appendixes A-1 through A-5. The survey identified the following common problems and concerns related to wheel/rail profiles and wheel/rail interaction in transit operation: • Adoption of low wheel flange angles can increase the risk of flange climb derail- ment. High flange angles above 72 degrees are strongly recommended to improve operation safety. • Rough wheel surface finishes from wheel re-profiling can increase the risk of flange climb derailment. Final wheel surface finish improvement and lubrication could mitigate the problem considerably. • Introduction of new wheel and rail profiles need to be carefully programmed for both wheel re-profiling and rail grinding to achieve a smooth transition. • Without adequate control mechanisms, independently rotating wheels can produce higher lateral forces and higher wheel/rail wear on curves. • Cylindrical wheels may reduce the risk of vehicle hunting, but can produce poor steer- ing performance on curves. • Some wheel and rail profile combinations used in transit operations have not been systematically evaluated to ensure they have good performance on both tangent track and curves under given vehicle and track conditions. • Severe two-point contact has been observed on the designed wheel/rail profile combinations from several transit operations. This type of contact tends to produce EFFECT OF WHEEL/RAIL PROFILES AND WHEEL/RAIL INTERACTION ON SYSTEM PERFORMANCE AND MAINTENANCE IN TRANSIT OPERATIONS

A-4 poor steering on curves, resulting in higher lateral force and a higher rate of wheel/rail wear. • Track gage and restraining rails need to be carefully set on curves to allow suffi- cient RRD and to reduce some high rail wear and lateral force. • Wheel slide and wheel flats occur on several transit systems, especially during the fall season. Although several technologies have been applied to mitigate the prob- lem, transit operators are in need of more effective methods. • Generally, noise related to wheels and rails is caused by wheel screech/squeal, wheel impact, and rail corrugations. Wheel/rail lubrication and optimizing wheel/rail contact could help to mitigate the noise problems. • Wheel/rail friction management is a field that needs to be further explored. Appli- cation of wheel/rail lubrication is very limited in transit operation due to the com- plications related to wheel slide and wheel flats. • Reduction of wheel/rail wear can be achieved by optimization of wheel/rail pro- files, properly designed truck primary suspension, improvement of track mainte- nance, and application of lubrication. • Without a wheel/rail profile measurement and documentation program, transit operators will have difficulty reaching a high level of effectiveness and efficiency in wheel/rail operation and maintenance. • Further improvement of transit system personnel understanding of wheel/rail pro- files and interaction should be one of the strategic steps in system improvement. With better understanding of the basic concepts, vehicle/track operation and main- tenance activities would be performed more effectively.

A-5 CHAPTER 1 INTRODUCTION This project included two phases (Table A-1). This report describes the methodology and engineering behind wheel/rail profile optimization and the results derived from the work performed in Task 1, Phase I of the program. 1.1 BACKGROUND A railroad train running along a track is one of the most complex dynamic systems in engineering due to the many nonlinear components. The interaction between wheels and rails is an especially complicated nonlinear element of the railway system. Wheel and rail geometry—involving cross section profiles, geometry along the direction of travel, and varying shapes due to wear—has a significant effect on vehi- cle dynamic performance and operating safety. Transit systems are usually operated in dense, urban areas, which frequently results in lines that contain a large percent- age of curves, or curves with small radii, which can increase wheel and rail wear and increase the potential for flange climb derailments. Transit systems also operate a wide range of vehi- cle types, such as those used in commuter rail service, heavy or rapid transit and light rail vehicles, with a wide range of sus- pension designs and vehicle performance characteristics. In general, transit systems (in particular, light rail and sub- way systems) are locally operated. Without the requirement of interoperability, many transit systems have adopted different wheel and rail profile standards for different reasons. Some of these standards are unique to a particular system. Older sys- tems frequently have wheel and rail profile standards that were established many years ago. For some older systems, the rea- sons that specific profiles were adopted have been lost in time. Newer systems have generally selected the wheel/rail profiles based on the increased understanding of wheel/rail interaction. Increasing operating speed and introducing new designs of vehicles have further challenged transit systems to maintain and improve wheel/rail interaction. Good overall perfor- mance can be achieved by optimizing vehicle design, includ- ing suspension and articulation, to work with optimized wheel and rail profiles. However, possibilities of modifying existing vehicles are limited. Along with other activities, optimization of wheel/rail contact is one of the strategies for maintaining or improving vehicle performance. 1.2 OBJECTIVES There are two main objectives of wheel/rail profile assess- ment technology development: • Identify common problems and concerns related to wheel/rail profile and interaction in transit operations. • Provide guidelines to transit system operators for wheel/ rail profile assessment, monitoring, and maintenance. This appendix fulfills the requirement of the first objective. Program Tasks Task 1 Define common problems and concerns related to wheel/rail profiles in transit operation Phase I Task 2 Propose preliminary flange climb criteria for application to transit operation Task 1 Develop general guidelinesfor wheel/rail profile assessment applied to transit operation Phase II Task 2 Propose final flange climb derailment criteria validated by the test data TABLE A-1 Tasks in the program of wheel/rail profile optimization technology and flange climb criteria

CHAPTER 2 METHODOLOGY To develop wheel/rail profile assessment technology, the existing problems and concerns related to wheel and rail pro- files in transit operations first need to be identified. A survey has been conducted of selected transit systems to examine the current state of common practices in wheel/rail operation and maintenance. 2.1 SELECTION OF SYSTEMS FOR SITE VISITS The research team compiled a partial list of transit systems based on the 2003 Membership Directory of American Public A-6 Transportation Association (1) and the research team’s knowl- edge of these systems, as shown in Table A-2. These systems operate a large number of cars and have a variety of types of operation. They are mainly located in four geographic areas: • Washington, D.C.—Baltimore • Chicago • California • the Northeast (Boston–New York–Philadelphia) The research team visited several of these transit agencies to perform the survey. Due to budget limitations, the team sur- Transit System Light Rail Cars Bi- level Rapid Transit Commuter Coach Locomotive Total Geographic area 1 San Francisco Bay Area Rapid Transit (BART) 669 669 2 San Francisco Municipal Railway 136 136 California 3 Southern California Regional Rail Authority (Los Angeles) 146 37 183 4 Metropolitan Atlanta Rapid Transit Authority 238 238 Atlanta 5 Chicago Transit Authority 1190 1190 Chicago 6 Chicago Metra 781 165 139 1085 7 Massachusetts Bay Transportation Authority 185 408 362 80 1035 8 New Jersey Transit Corporation (NJ TRANSIT) 45 844 139 1028 Northeast 9 Port Authority Transit Corporation (Lindenwold, NJ) 121 121 10 Metropolitan Transportation Authority (New York) 8231 8231 11 Port Authority Trans-Hudson Corporation (New York) 342 342 12 Southeastern Pennsylvania Transportation Authority 197 345 349 891 13 Maryland Transit Administration 53 100 110 30 293 Washington 14 Washington Metropolitan Area Transit Authority 882 882 D.C. /Baltimore Area Agencies Visited Trip 1 Northeast • • N MBTA • • • • ew Jersey Transit Corporation (NJ TRANSIT) Trip 2 Washington, D.C. and Philadelphia Washington Metropolitan Area Transit Authority (WMATA) SEPTA Trip 3 Chicago area Chicago Transit Authority (CTA) Chicago Metra (not included in the summaries of site visits) TABLE A-2 List of large transit systems TABLE A-3 Transit systems visited during the survey

veyed six systems in three main geographic areas (Table A-3). These six systems are considered representative of transit operations in North America. 2.2 SITE VISIT During each site visit, the following information was researched: • Current problems related to the wheel/rail profiles in that system. • Historical information of wheel/rail related problems. • Map of route, curve distribution, and operating speed. • New wheel/rail profile designs. • Worn wheel/rail profiles, if available. • Wheel/rail wear historical data. • Vehicle design information. • Rail lubrication practices. • Current wheel/rail maintenance practice. • Any other wheel/rail related problems. Results from the individual surveys are contained in the Appendixes A-1 to A-5. A-7 2.3 ANALYSIS OF SURVEY INFORMATION The research team has carefully studied the information from the survey. Analysis has been performed with an emphasis on the wheel/rail profiles and issues related to wheel/rail interaction. These issues include the following: • Typical wheel/rail profiles used in transit operations. • Wheel/rail contact patterns. • Wheel/rail wear patterns. • Safety concerns related to wheel/rail profiles. • Vehicle curving performance and lateral stability behavior as affected by wheel/rail profiles. • Other issues related to wheel/rail profiles. 2.4 IDENTIFYING COMMON WHEEL/RAIL PROFILE ISSUES Based on the survey and the survey information analysis, the common problems and concerns related to wheel/rail pro- files in transit systems were identified and are further sum- marized in this appendix. Based on the survey, there is a clear understanding of what guidelines transit operators need related to wheel/rail profiles.

CHAPTER 3 TRANSIT SYSTEM SURVEY As a way of focusing expectations, prior to each visit to the representative transit systems, a questionnaire was sent to a primary contact person at each location focusing on the fol- lowing topics: • Existence and type of wheel/rail profile related prob- lems on the system. • Remedies tried (successfully or not) for the wheel/rail problems. • Determining whether the problems are specific to par- ticular vehicle types and/or track locations. • Opinions of existing track and/or car conditions versus design and maintenance standards. • Lubrication practices. • Employee wheel/rail interface training needs. • Existence of a wheel re-profiling program. • Existence of, and criteria for, a rail grinding program. • Percentage of budget spent on various facets of wheel/rail maintenance. • Any other vehicle performance research. • Driving factors behind the wheel/rail work (e.g., eco- nomics, safety). • Major corrections needed to improve wheel and rail interaction. Each visit began with a presentation on the effect of wheel/rail interaction on vehicle performance to groups that included track maintenance, vehicle maintenance, and operating personnel. This presentation (approximately 1 hour long) was intended to improve the group’s under- standing of wheel/rail contact systems and the importance of wheel/rail profile optimization and to stimulate discussion A-8 of wheel/rail issues. Five major topics were included in the presentation: • Fundamentals of wheel and rail contact. • Vehicle dynamics related to wheel and rail shapes. • Problems caused by incompatible wheel/rail profiles. • Wheel/rail lubrication. • Wheel/rail maintenance. After the initial seminar, a group discussion was held to explore wheel/rail topics. With the involvement of personnel from operations, track maintenance, and vehicle maintenance, many problems and concerns were reviewed at a systems level. The discussion continued with individual interviews, during which the research team collected much information related to practice, standards, and rules. At each site visited, a wheel/axle/car shop tour was conducted with a primary mechanical representative. Then, an on-track visit and dis- cussion was performed with an engineering representative. Appendixes A-1 to A-5 provide a brief summary of the information from each individual system visited. These sum- maries have been reviewed by the relevant systems to ensure the accuracy of the information. The topics in each summary include the following: • Wheel and rail profiles. • Wheel life and wheel re-profiling. • Rail life and rail grinding. • Track standards. • Fixation methods. • Lubrication and wheel slide. • Noise. • Major concerns and actions.

CHAPTER 4 COMMON PROBLEMS OR CONCERNS RELATED TO WHEEL/RAIL PROFILES The common problems and concerns discussed in this sec- tion are summarized from the survey information. They may not apply to every transit system. An issue is addressed here because it was of interest or was considered by more than one system and because it falls into the general area of wheel/rail interaction. In this section, the following issues related to wheel/rail profiles and wheel/rail interactions are discussed: • Wheel flange angle. • Surface finish from wheel re-profiling. • System transition in increasing wheel flange angle. • Independently rotating wheels. • Cylindrical tread wheels. • Wheel/rail contact condition analysis. • Track gage and flangeway clearance. • Wheel slide and wheel flats. • Noise. • Rail lubrication. • Wheel/rail wear. • Wheel/rail profile monitoring and documentation. A brief description of the theories related to each issue is provided for a better understanding on the cause of the prob- lem and the damage that might result. 4.1 WHEEL FLANGE ANGLE The maximum flange angle of the designed wheel profiles applied in transit operation ranges between 63 and 75 degrees. Table A-4 lists the wheel flange angles received for the six visited systems. It was noticed that the wheel profile drawings received from some systems have no direct measure of wheel flange angle. Some flange angles listed in Table A-4 were obtained by converting the wheel profile drawings received to CAD drawings. Then the flange angles were accurately derived from the CAD drawings. During the survey, when asked about the flange angle, the engineers in the vehicle mainte- nance group usually would only reference the drawings but not know the actual angle if there was no direct measure of flange angle in the drawing. The maximum wheel flange angle (δ) is defined as the angle of the plane of contact on the flange relative to the hor- izontal (Figure A-1), and it has a significant effect on wheel flange climb derailment. Figure A-1 illustrates the system of forces acting on the flange contact point. Lateral force (L) and vertical force (V) are exerted on the rail by the wheel. Reacting forces exerted on the wheel by the rail are the nor- mal force (F3) and the lateral creep force (F2) in the plane of contact. A-9 System Light Rail Cars Flange Angle Rapid Transit Cars Flange Angle Commuter Cars Flange Angle MBTA 63 degrees (in the transition to 72 degrees) No information was received No information was received NJ TRAN SIT 75 degrees 72 degrees SEPTA 60-65 degrees (in specified tolerance) 63 degrees 72 degrees WMATA 63 degrees Chicago Metra 75 degrees CTA 68 degrees TABLE A-4 Maximum wheel flange angle of designed wheels (the blank indicates no such service in that system)

Equating forces in the lateral and vertical directions give the following equation: (2) (A-1) This equation gives the minimum L/V ratio at which flange climb derailment can occur for any value of F2/F3 at a specified maximum contact angle. Nadal’s criterion (3), pro- posed in 1908 and still used extensively for derailment assessment, can be derived from Equation A-1 for the satu- rated condition of where µ = the coefficient of friction between the wheel and the rail (see Equation A-2): (A-2) If the maximum contact angle is used, Equation A-2 gives the minimum wheel L/V ratio at which flange climb derail- ment may occur for the given contact angle and friction coef- ficient µ. In other words, below this L/V value, flange climb cannot occur. Figure A-2 plots the relation of limiting L/V ratio and maximizing flange angle at different levels of fric- tion coefficient between wheel and rail. Figure A-2 gives two examples of wheel flange angles. One is the AAR-1B wheel profile with a 75-degree flange L V = − + tan tan δ µ µ δ1 F F 2 3 = µ L V F F F F = − + tan tan δ δ 2 3 2 31 A-10 angle, and the other wheel profile has a 63-degree flange angle. At a friction coefficient of 0.5, which is the dry wheel/rail contact condition, the limiting L/V value is 1.13 for wheel profiles with a 75-degree flange angle (such as the AAR-1B wheel) and 0.73 for the wheels with a 63-degree flange angle. Clearly, wheels with low flange angles have a higher risk of flange climb derailment. Increasing the design wheel flange angle to reduce the risk of flange climb derailment has been a common practice for transit systems. Due to historic reasons, some older transit sys- tems have adopted relatively low wheel flange angles in the range of 63 to 65 degrees. The low flange angles are prone to flange climb derailment and have less compatibility with dif- ferent truck designs. Newer transit systems generally start with a wheel profile having a flange angle of 72 to75 degrees. A wheel profile with a higher flange angle can reduce the risk of flange climb derailment and can have much better compatibility with any new designs of vehicle/truck that may be introduced in the future compared to wheels with lower flange angles. Also, with higher L/V ratio limits (according to the Nadal flange climb criterion), high flange angles will tolerate greater levels of unexpected track irregularity. 4.1.1 Derailments of Low Floor Light Rail Vehicles Due to Low Flange Angle Figure A-3 compares two examples of designed wheel profiles used by transit systems. First is a wheel profile with a flange angle of 63 degrees that was previously applied to all vehicles on MBTA’s Green Line (light rail), including new Number 8 cars. The second example is the profile applied to the NJ TRANSIT’s Newark city subway (light rail) with a flange angle of 75 degrees. As shown in Figures A-4 and A-5, MBTA’s Number 8 cars have a structure similar to that of the NJ TRANSIT light rail cars (LRVs) with the low-platform level boarding and low floor for handicapped accessibility. These types of cars have three sections and double articulation at the center unit. The center unit is equipped with independent rotating wheels. Figure A-1. Flange forces at wheel climb. Figure A-2. Relationship of limiting wheel L/V ratio and maximum flange angle. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 45 55 65 75 85 Flange Angle (Degree) N ad al L /V V al ue 1.0 0.5 0.1 0.2 0.3 0.4 Figure A-3. Examples of designed wheel profiles.

The cars from these two light rail systems show different dynamic performance due to the differences in suspension and wheel profile design. However, the 63-degree wheel flange angle, combined with other track and vehicle situations, appar- ently contributed to derailments of the Number 8 cars in 2000 and 2001. One of MBTA’s remedial actions has been to increase the wheel flange angle from 63 degrees to 75 degrees by introducing a new wheel profile. Rail grinding has also been performed to reshape the rail gage corner to help the wheels maintain the 75-degree flange angle. Combined with other improvements in track maintenance, the derailment of the Number 8 cars due to the low flange angle has been eliminated. In comparison, there are no derailment concerns with the similar cars on the NJ TRANSIT subway system. The wheels in the cars were designed with a 75-degree flange angle. 4.1.2 Derailment of Rapid Transit Vehicles Due to Low Flange Angle To reduce wheel and rail wear, WMATA adopted the British worn tapered wheel profile in 1978 to replace the old cylindrical profile. This wheel profile has a 63-degree flange A-11 angle. In 1993, six low speed flange climb derailments occurred on curves in the yards. Guardrails were installed later in those derailment locations. In August 2003, a flange climb derailment occurred on a service train. Among other causes, the consultant for the derailment investigation has suggested that the 63-degree flange angle may have increased the risk of flange climb derailment. WMATA has been considering the improvement of wheel profile to a larger flange angle of 72 to 75 degrees. 4.1.3 Additional Transit System Wheel Profile Designs Among the 14 wheel profile drawings of U.S./North American light rail systems that are included in the Track Design Handbook for Light Rail Transit (excluding SEPTA and MBTA wheel profiles, which have been discussed in Table A-4), 8 have no direct measures of flange angle, and 2 of the remaining 6 have a design flange angle of 63 degrees (4). This handbook proposed a wheel flange angle of 70 degrees based on Heumann’s design. The APTA’s Passen- ger Rail Safety Standard Task Force Technical Bulletin (5) provides guidance on reducing the probability of wheel- climb derailment, suggesting a minimum wheel flange angle of 72 degrees (suggested tolerances are +3.0 degrees and −2.0 degrees). 4.2 WHEEL RE-PROFILING 4.2.1 Rough Surface from Wheel Re-Profiling Wheel truing is a process that re-profiles the wheel shape and removes surface defects such as flats, spalls, and shellings. Two types of wheel re-profiling machines are com- monly used. Figure A-6 shows the milling type, which has a cutting head with many small cutters. The arrangement of the cutters forms the wheel profile. Figure A-7 shows the lathe type, which has a wheel profile template; the single cutter cuts the wheel by following the shape of a template. Figure A-5. NJ TRANSIT LRV. Figure A-4. The Number 8 car of MBTA Green Line. Figure A-6. Milling type wheel re-profiling machine.

Several systems have reported flange climb derailments occurring at curves or switches in yards when the cars were just out of the wheel re-profiling machines. This type of derailment was likely caused by the wheel surface roughness after wheel re-profiling. Figure A-8 compares the wheel sur- faces just after re-profiling and the surface after many miles of running. The left wheel in Figure A-8 was re-profiled by the milling type machine with very clear cutting traces on the surface. The middle wheel was re-profiled by a lathe type machine with shallower cutting traces. The right wheel was returned to the shop from service with a smooth surface but had a flat spot on the tread. A-12 Generally, the coefficient of friction for dry and smooth steel-to-steel contact is about 0.5. The effective coefficient of friction for rough surface condition can be much higher. For example, if the friction coefficient reaches 1.0, the L/V limit would be 0.5 for a 75-degree flange angle and 0.3 for a 63-degree flange angle (as shown in Figure A-2). Therefore, the rough surface produced by wheel re-profiling could sig- nificantly reduce the L/V limit for flange climb. The low flange angle further increases the derailment risk. Several remedies may improve the surface condition: • Frequently inspecting the cutting tools—especially for the milling type machine. Dulled tools can produce a very rough surface. Sometimes the grooves on the wheels were obvious. • Addressing the final surface tuning. In this step, there is no significant material removal but rather a light cut for smoothing the surface. WMATA has included this step in its wheel re-profiling procedures. Further, lubrication after re-profiling can be an effective way to prevent flange climb derailment on newly re-profiled wheels. Again, referring to Figure A-2, reducing the friction coefficient at wheel/rail interface can increase the L/V limit for flange climb. The sharp asperities on the wheel surface after re- profiling may quickly deform or wear off in operation due to very high locally concentrated contact stress. After some Figure A-7. Lathe type wheel re-profiling machine. Figure A-8. Comparison of wheel surface roughness. (a) Surface after wheel re-profiling from milling type machine, (b) Surface after wheel re-profiling from lathe type machine, and (c) surface of wheel back from operation with a flat spot. (a) (b) (c)

distance of operation, the wheel surface should be smoother. Light lubrication can help wheels safely pass this rough-to- smooth transition. WMATA now manually lubricates all wheels immediately after re-profiling. CTA has installed way- side lubricators on the curves as well as guardrails in their yards. 4.2.2 Wheel Diameter Difference after Re-Profiling Improper setting of tools or wheelset position during re- profile can cause a diameter difference in wheels on the same axle. The difference in diameter between two axles in the same truck can be caused by varying material removal rates. The difference in diameter for the wheels in the same (cou- pled) axle could lead either to the truck running offset if two axles in the same truck have a similar pattern of diameter dif- ference or to unstable truck performance if only one of the axles has the diameter difference. In this situation, one axle tends to drag the truck to an offset position while the other axle tends to pull the truck back to the track center. The sit- uation will be even more complicated if both axles have dif- ferences in diameter but with different patterns. Table A-5 lists the diameter tolerances used in several transit systems. 4.2.3 Introducing New Wheel/Rail Profiles Introduction of a new wheel profile or a new rail profile will require a transition period to bring the wheel/rail system into equilibrium. Wheels and rails in a system generally wear into a confor- mal, stable state in terms of the profile shapes. If either wheel or rail profile needs to be redesigned and the new profile has a significantly different shape compared to the existing pro- file, the existing wheel/rail conformality will be lost. A pro- gram needs to be carefully designed for a smooth transition to reach a new equilibrium of wheel/rail contact. A-13 As discussed in Section 4.1, several transit systems have adopted wheel profiles with relatively low flange angles due to historic reasons. To reduce the risk of flange climb and increase safety margins, some systems have started or intend to adopt new wheel profiles with higher flange angles. If only wheel profiles are changed, the initial situation of a new wheel with higher flange angle contacting with an existing worn rail with lower gage angle would be likely (see Figure A-9). Because of the different angles at the wheel flange and the rail gage, the contact position at the flange is likely to be low and contact stress is likely to be high due to the small contact area. The 75-degree angle at the contact position shown in Figure A-9 will very likely wear into a lower angle (63 to 75 degrees). It may also result in severe two-point con- tact on curves and adversely affect truck steering. MBTA Green Line (light rail) faced this problem. The wheel profile used on both existing Number 7 cars and new Number 8 cars originally had a flange angle of 63 degrees. To reduce the risk of flange climb derailment on the Number 8 cars, MBTA Green Line implemented an Interim Wheel Profile (IWP) with a flange angle of 75 degrees for the Num- ber 8 cars. However, the transition from the old wheel pro- file to the new wheel profile with higher flange angle did not go smoothly on the Green Line. Due to the capacity of wheel re-profiling and rail grinding, many Number 7 cars (115 cars), the majority of the Green Line car fleet, were still equipped with wheels with a 63-degree flange angle (or slightly higher at worn condition) and some sections of worn gage face rail were still in use (with a gage angle of 63 degrees or slightly higher). These low existing angles on wheel flanges and rail gage faces continued to resist the pro- file transition and cause fast wear on the flanges of the few cars (10 to 20 cars) with 75-degree-flange-angle wheels. This high wear rate required very frequent re-profiling of the IWP wheels (as little as 3,000 operating miles between wheel re-profiling) in order to maintain the desired 75-degree flange angle. TABLE A-5 Examples of currently used diameter tolerance after wheel re-profiling System Diameter Tolerance after Wheel Re-profiling SEPTA 1/8 in. within the same axle 1/4 in. axle-to-axle in the same truck 1/2 in. truck-to-truck in the same car WMATA 1/16 in. within the axle 1/4 in. axle to axle in the same truck 1/2 in. truck to truck in the same car Chicago Metra 1/8-in. variation left-to-right within an axle 1/4 in. axle to axle within a truck 1/4 in. truck to truck within a car CTA 3/64 in. within an axle (0.046 in.) 1 in. axle to axle in the same truck 1 in. truck to truck within the same car

Therefore, when changing wheel (or rail) profile is necessary, a transition program should be carefully planned by consider- ing the capacity of both wheel re-profiling and rail grinding. If the profile change is significant, one or more interim profiles may be needed to gradually approach the desired profile. 4.3 INDEPENDENTLY ROTATING WHEELS Independently rotating wheels are generally used in Light Rail low-floor cars. Low-floor cars are used for the advantages of easier boarding and handicapped accessibility. Although only a few systems currently operate cars with independently rotating wheels, this issue is still worth discussion in consid- eration of introducing these types of vehicles in the future. Wheels mounted on a solid axle must move at the same rota- tional speed. To accommodate running in curves, a taper is usu- ally applied to the wheels. The wheelset shifts sideways, as shown in Figure A-10, to allow the outer wheel to run with a larger rolling radius than the inner wheel. The resulting longi- tudinal creep forces at the wheel/rail interface for wheels on the A-14 same axle form a moment that steers the truck around the curve. Previous flange climb studies indicate that as the ratio of longi- tudinal force and vertical force increases, the wheel L/V ratio required for derailment also increases (2). This is illustrated in Figure A-11. Therefore, the Nadal flange climb criterion can be relaxed based on the level of longitudinal force. The flange climb would occur at an L/V ratio above the Nadal limiting value when there is a significant longitudinal force. Independently rotating wheels do not produce longitudinal forces on curves to form the steering moment (Figure A-12). This leads to a higher wheelset AOA, higher lateral forces (until the saturation is reached), higher L/V ratios, and increased wheel and rail wear. Furthermore, without longitudinal force, any L/V values that exceed the Nadal limit will cause wheel flange climb. Therefore, independently rotating wheels have less tolerance to any track irregularities that may suddenly increase wheel lateral forces or reduce wheel vertical forces. The center unit of the Number 8 cars on MBTA Green Line is equipped with independently rotating wheels. As discussed in Section 4.1, combined with a low flange angle and other track and vehicle conditions, the independently rotating 0 4 8 12 16 20 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 Wheel L/V L /V d is ta n c e l im it ( ft ). Lo/V=0 Lo/V= 0.18 Lo/V=0.26 Lo/V=0.36 Lo/V=0.42 Lo/V=0.51 Lo/V=0.62 Figure A-10. Steering moment produced by longitudinal forces. Figure A-11. Effect of wheel longitudinal force on wheel L/V ratio limit. Figure A-9. Contact condition at wheel flange.

wheels are more prone to derail than the wheel mounted on a solid axle on the end trucks in the same vehicle. The center units of the low-floor cars on NJ TRANSIT are also equipped with independently rotating wheels. NJ TRANSIT reported that the independently rotating wheels have a slight tendency to climb the point of the switch if the switch is in a diverging position and is not properly adjusted. Point protections with housetops have been installed on all mainline turnouts to prevent wheel climbs. NJ TRANSIT has also observed that the wheels at the center truck have a higher wear rate compared to the wheels at end trucks due to a slight tendency to run against the low rail gage face in curving. In summary, vehicles with independently rotating wheels need to be carefully designed to control flange climb and wheel wear. Additional control mechanisms, such as link- ages or active control systems, can be used to steer wheelsets on curves and through track perturbations. Without such con- trol mechanisms, the wheel/rail profiles and vehicle/track maintenance will need to be much more strictly controlled and monitored to prevent wheel flange climb. 4.4 CYLINDRICAL TREAD WHEELS While most transit systems use tapered wheels, several transit systems use cylindrical tread wheels on their vehicles. Tapered wheels have a self-centering capability. On tan- gent track, the primary mode of guidance is the wheel’s conicity for tapered wheels. When the wheelset has a small lateral displacement from the center of the track caused by track disturbances or any asymmetry of the vehicle structure or response, one wheel will have a larger rolling radius and is moving forward faster than the other wheel. This induces a yaw motion that will move the wheelset back to the center of the track. However, if the wheelset repeatedly overshoots the center, kinematic oscillation can occur. Cylindrical wheels tend to allow large lateral displacement even on straight track when they encounter any asymmetry in track geometry, wheel and rail profile, or other vehicle related disturbances. There is no guidance until flange contact. Wheels would run off the track without the wheel flange. Wheel flanging could be a common scenario in operation for A-15 cylindrical wheels. The wheel lateral movement is usually in a long and irregular wave, as shown in Figure A-13, based on the vehicle and track conditions. It is a different scenario from the lateral oscillation of vehicle hunting, which reflects the truck’s lateral movement with constant frequency, initiated by the resonance response of the vehicle and track system. On sharp curves and on switches and crossings, the flanges become the essential mode of guidance. Wheel flanging involves contact in a similar way for both tapered wheels and cylindrical wheels. However, the cylindrical wheels tend to produce severe two-point contact because the wheel tread tends to always be in contact with the rail and has a large dif- ference in rolling radius compared to that of the contact point at flange. A slightly wide gage, which is a practice commonly applied in operation, can increase the RRD for tapered wheels on curves as illustrated in Figure A-14, but has no effect on cylindrical tread wheels. On shallow curves, without flange contact, the AOA of an axle equipped with cylindrical tread wheels may be higher than that of tapered wheels due to lack of RRD. Cylindrical wheels also tend to have more flange wear resulting in thin flange due to frequent flange contact. SEPTA uses a cylindrical tread wheel profile (63-degree flange angle) on their light rail vehicles (LRVs) operating on Routes 101 and 102. This wheel profile was inherited from previous cars operated on these lines. When new, these cylin- drical wheels tend to wear quickly to a slightly hollow tread (see Figure A-15). They then stabilize in this shape for a rea- sonably long period. Field observations of tangent tracks on the Route 101 indicated a narrow contact band toward the gage face of the rail. Figure A-12. Contact forces on wheels of coupled axle (left) and independent wheels (right). Left wheel flanging right wheel flanging Track center line Figure A-13. Lateral movement of cylindrical tread wheelset.

CTA uses the historical AAR narrow flange cylindrical tread profile with a flange angle of about 68 degrees. This profile was adopted by CTA in the 1930s to eliminate vehi- cle hunting that occurred between 60 and 80 mph on high- speed inter-city cars. This cylindrical profile has been performing well based on CTA’s report. It is likely the result of two major factors: • CTA is a system with a high percentage of tangent tracks • CTA has a light axle load compared to other rapid tran- sit systems The issue of reduced ride quality due to the lateral sliding that is usually associated with cylindrical wheels has not been raised as a problem, according to SEPTA and CTA. 4.5 WHEEL/RAIL CONTACT CONDITION ANALYSIS The contact characteristics of a wheel and rail combination have significant effects on vehicle performance. The effec- tive conicity resulting from the wheel tread contacting the rail head can influence the vehicle’s lateral stability on tan- A-16 gent track, and the compatibility of the wheel flange root con- tacting the rail gage face can considerably affect the truck’s curving performance. In this section, the contact conditions of several wheel and rail combinations from the surveyed systems are presented to discuss their likely effects on vehicle performance. Table A-6 lists the combinations of wheel and rails. Note that all wheels and rails listed in Table A-6 are in the designed shape. They represent the initial contact situations. Since most transit systems surveyed have no profile mea- surement devices except the “go” or “no-go” gages, no mea- sured worn wheel and rail profiles were received during the survey. 4.5.1 Curving Indications Figures A-16, A-18, and A-19 show the wheel and rail combinations listed in Table A-6 at the flange contact condi- tion, which provides an indication of wheelset curving per- formance. Three contact patterns are observed. Figure A-15. SEPTA cylindrical wheel wears into slightly hollow, but stable shape on Suburban Route 101, LRV. Moving direction Figure A-14. Increase RRD by widening gage: (left) standard gage and (right) wider gage. TABLE A-6 Wheel and rail combinations Wheel Profiles Rail Profile Rail Cant CTA (rapid transit, cylindrical) 115RE 1:40 WMATA (rapid transit, 63 degree flange angle) 115RE 1:40 SEPTA (rapid transit, 63 degree flange angle) 115RE 1:40 MBTA (light rail, 63 degree flange angle) 115RE 1:40 MBTA (light rail, 75 degree flange angle) 115RE 1:40 SEPTA (light rail) 115RE 1:40 SEPTA (light rail, cylindrical) 100RB 1:40 New Jersey Transit (light rail) 115RE 1:40 SEPTA (commuter) 132RE 1:40

Four wheel/rail pairs in Figure A-16 show severe two- point contact, which features one contact point at the wheel tread/rail head and a second at the wheel flange/rail gage face. The gap between the wheel flange root and the rail gage corner is larger than 0.08 in. (2 mm). This type of wheel and rail combination may never wear into conformal contact before the next wheel re-profiling (or rail grinding). Severe two-point contact can reduce truck steering on curves, because the longitudinal creep forces generated at the two points of contact can act in opposite directions due to the RRD at the two contact points. As illustrated in Figure A-17, the resultant steering moment would be reduced under this condition. Severe two-point contact can lead to higher wheelset AOA, higher lateral forces, higher rolling resis- tance, or a higher rate of wheel and rail wear. Figure A-18 represents a medium level of two-point con- tact. The gap at the wheel flange throat is less than or equal to 0.04 in. (1 mm). This is more likely to wear into the con- formal contact condition before the next wheel re-profiling (or rail grinding), depending on the wear rate. This type of contact starts with a similar situation as the first group with a A-17 smaller RRD between the two contact points on the same wheel. Figure A-19 represents the conformal contact condition. Close conformal (one-point) contact provides better truck steering ability on curves than severe two-point contact. Figure A-16. Examples of severe two-point contact: (a) MBTA—light rail (Green Line, 63 degree flange angle), (b) SEPTA—light rail (101&102 Line), (c) SEPTA—light rail (Green Line), and (d) CTA—rapid transit. (a) (c) (b) (d) Figure A-17. Truck steering moment reduction in two-point contact, due to the opposite directions of longitudinal forces on the outer wheel.

Contact stress is also lower at the rail gage face in confor- mal contact because it results in a larger contact area. Conformal contact has been a recommended contact pat- tern for rail operations to improve truck steering, reduce lat- eral forces, and reduce contact stresses to lower the risk of rolling contact fatigue (6). A-18 4.5.2 Lateral Stability Indications The effect of wheel and rail profiles on vehicle lateral sta- bility on tangent track is indicated by the effective conicity. Figure A-20 illustrates contact conicity using a coned wheel. With the wheelset centered on the track, both wheels have the Figure A-18. Medium level of two-point contact: (a) SEPTA rapid transit and (b) SEPTA commuter. Figure A-19. Conformal contact: (a) NJ TRANSIT light rail, (b) WMATA rapid transit, and (c) MBTA light rail—interim wheel profile with 75-degree flange angle. (a) (b) (a) (b) (c)

same rolling radius. As the wheelset is shifted laterally (to the left in Figure A-20), the right wheel rolling radius (rR) decreases and the left wheel radius (rL) increases, thereby generating an RRD. The rate of change of radius for coned wheels with lateral shift depends on the cone angle λ, which is known as the conicity. In general, the effective conicity is defined by Equation A-3 (6): (A-3) where y is wheelset lateral shift. In normal operation on tangent track, the wheelset oscillates about the track center due to any vehicle and track irregularities (Figure A-21). Because the vehicle and track are never absolutely smooth and symmetric, this self-center capability induced by the cone-shaped wheel tread maintains the truck run- ning around the track center. However, as speed is increased, the lateral movement of the wheelset can overshoot if the conicity is high and generate large amplitude oscillations with a well- defined wavelength. The lateral movements are limited only by the contact of wheel flanges with the rail. This unstable behav- ior at higher speeds is referred to as “truck hunting.” Hunting predominantly occurs in empty or lightweight vehi- cles. The critical speed is highly dependent on the truck char- acteristics. As conicity increases, the critical speed of hunting onset decreases. For this reason, it is important when designing wheel and rail profiles to ensure that the intended operating speed for a given truck is below the critical hunting speed. Figure A-22 displays the RRD (for a solid axle wheelset) relative to wheelset lateral shift for the six wheel/rail combi- nations included in Table A-6. The wheelset lateral shift Effective Conicity RRD y = 2 A-19 range before reaching flange contact is between 0.18 in. and 0.24 in. for these combinations on a standard gage of 56.5 in. Half of the slope of each line (RRD/lateral shift as defined by Equation A-3) in the lateral shift range before reaching flange contact is the effective conicity for each individual combination. Except for the wheel used in WMATA, the combina- tions produced very low conicities (below 0.05) around the −0.2- to 0.2-in. lateral shift range, which indicates a low risk of lateral instability on tangent track from the aspect of wheel and rail profiles. Note that two of these wheels have a cylindrical tread. The WMATA wheel produces a relatively higher conicity of 0.33 on average in the lateral shift range of −0.2 to 0.2 in. This value is considered to be higher than the general prac- tice (less than 0.2) and could increase the risk of hunting on tangent track at certain speeds. However, because the truck suspensions also play an important role in hunting, a com- prehensive investigation including both vehicle and track conditions at WMATA would be needed in order to deter- mine the hunting onset speed and to conclude whether a change in the wheel profile would be required. During the survey, WMATA reported that infrequent and somewhat transient hunting has been noticed to occur at spe- cific track locations on the system. The lateral movements have never been severe and seem to be driven by specific combinations of vehicle and track. WMATA also makes the track gage 1/4 in. tighter on mainline tangent and on curves of less than 4 degrees. A maximum speed of 75 mph on the system is possible, but now it is restricted to 59 mph for energy conservation and equipment longevity. Therefore, it is possible that the critical hunting speed is above the current operating speed. Conversely, the WMATA wheel profile should have better performance on shallow curves due to its large RRD compared to the other wheel profile evaluations in this study. On shallow curves (below 2 or 3 degrees), the wheelset lateral shift tends to be small and generally with- out flange contact. Cylindrical wheels and wheels with very low conicity can produce zero or very small RRD, as Figure A-20. Wheelset on rails, coned wheelsets (λ = conicity). Figure A-21. Wheelset lateral oscillations on tangent track. -0.8 -0.4 -0.2 0 0.2 0.4 0.6 0.8 -0.4 -0.2 0 0.2 0.4 Wheelset Lateral Shift (inch) R o ll in g R a d iu s D if fe re n c e ( in c h ) septa-green septa101-102 cta wmata NJlight mbtalight Figure A-22. RRD versus wheelset lateral shift.

discussed above. Low RRD has a negative effect on vehi- cle curving performance. 4.5.3 Summary of Wheel/Rail Contact Analysis Wheel and rail profiles are critical to system performance. In straight track, lower conicity increases the critical hunting speed. In contrast, in curved track, higher conicity enables wheelsets to achieve a lateral position near the free rolling position at small values of lateral shift. These two objectives should be achieved by controlling both wheel and rail pro- files. A thorough study should be conducted before intro- ducing any new profiles into service. Static analysis can be used as a first step in the design of appropriate profiles. Dynamic analysis is needed to verify that the designed pro- files will perform well under given vehicle and track condi- tions. Limited track tests should also be conducted, if possi- ble, to confirm the analysis results. 4.6 RRD, TRACK GAGE, AND RESTRAINING RAILS To properly negotiate curves, the outer wheel needs to travel a longer distance than the inner wheel. For tapered tread wheelsets, this is achieved by running with different rolling radii (Figure A-23). The RRD required for pure rolling is a function of wheel diameter, rail gage, and track curvature. Figure A-24 displays examples of RRD for three nominal diameters of wheels on a standard track gage of 56.5 in. Due to the limit of wheel flange/rail gage clearance (8 to 10 mm), flange contact usually occurs on curves above 3 degrees. For cars with softer primary suspensions, flange contact may happen on curves 1 or 2 degrees higher. With- out severe two-point contact, the flange contact will produce a large RRD to assist wheelset curving. Figure A-14 illus- trates how widening the gage, a practice that has been regu- A-20 larly applied in transit track maintenance on curves, can increase RRD for tapered wheels. However, the limit of gage widening needs to be set carefully based on the total wheel width, gage, and track curvature. On sharp curves, to reduce wear at the gage face of the high rail and to reduce the risk of flange climb, restraining/guard rails are usually installed inside the low rail (Figure A-25). When properly set, the clearance between the restraining/ guard rail and the low rail can allow the wheel to generate suf- ficient RRD to mitigate some high rail wear and transfer some lateral force to the restraining/guard rail. This clearance needs to be carefully set. If this clearance is set too tight, the RRD required for curving can be significantly reduced because the restraining rail limits wheelset lateral shift. Consequently, rolling resistance can increase considerably due to high creep- ages (possibly wheel slide) leading to high creep forces and wheel/rail wear. 4.7 WHEEL SLIDES AND WHEEL FLATS All transit systems surveyed have experienced wheel slid- ing and, consequently, wheel flat problems. Significant main- tenance efforts and cost have been devoted to reduce wheel slide and wheel flats. Figure A-23. RRD on curves. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0 2 4 6 8 10 12 Curvature (degree) R eq ui re d Ro lli ng D iff er en ce (in ch ) 36 in wheel 33 in wheel 26 in wheel Figure A-24. RRD required for pure rolling. Figure A-25. Constraint of wheelset lateral shift from restraining/guard rail.

Wheel slide is caused by velocity differences between wheel and rail. It will lead to wheel flats, increased noise, sig- nificant impact forces that can damage track, and degraded ride quality. Wheel slide and flats are especially problematic during the fall season due to leaf residue contaminating the rails. Track routes closer to vegetation are most susceptible, whereas routes away from trees (elevated, subway, and between expressway lanes) are less affected. Both traction and braking may lead to wheel slide. How- ever, the existing literature and the survey interviews indicate that slides due to braking are more common. Magel and Kalousek report that skid flats for transit and passenger oper- ations are due primarily to rapid and frequent brake applica- tions under light axle loads, highly variable friction coeffi- cients, and general over-capacity of the braking systems (7). Based on the investigation conducted by Kumar and reported in TRB’s Research Results Digest 17 (8), chemical analyses were performed on contaminants from three U.S. transit systems indicating rust (iron oxides), dirt (silica and aluminum), and road salts (potassium, calcium, sodium, chlorine, and sulphur). Oils included petroleum products and vegetable oils as found in pine and cedar trees. The dry con- taminants themselves were not problematic, but only small amounts of water or oil were needed to form pastes that sig- nificantly reduced adhesion. Heavy rains were less of a fac- tor because they tend to wash the rails. The flats may occur immediately as a result of abrasion (especially with cast iron tread brakes) or after additional cyclic loading (mileage) due to Martensite formation (9). Initially, the flats will have definite corners, which will round off after sev- eral miles of operation. With a deep, freshly slid flat, a concrete tie can be cracked at 56 mph. After rounding, however, a speed of 90 mph was required to crack the concrete tie (10). The impacts caused by a single wheel flat or by a smooth wheel on special trackwork can produce transient sound pressure levels that are 7 to 10 dBA higher than the operation without the impacts (11). Therefore, the potential damage or noise will increase with the size of the impact. Note that lesser dynamic forces emanating from rough track, not com- plete discontinuities, can also create excessive reaction forces and noise. The noise created by impacts is usually quite noticeable above other sound and is a potential public relations problem. The dynamic forces created by wheel impacts or rough track may be damaging to the wheel or rails themselves. Tunna reports that rail strain can easily double due to a wheel flat (10). Alternatively, the force levels may be acceptable for the wheel/rail interface but could cause problems when trans- mitted to secondary structures. Wheel impacts can damage the ties, plates, ballast, and supporting or nearby structures (e.g., bridges). Even if these secondary structures are not damaged, they can become the prime radiator of secondary noise or vibration, including rattling of ties on plates and amplification by girder natural frequencies. In these cases, resilient rail fixation may A-21 reduce noise radiated from steel elevated structures and girders (11). To control wheel slide and wheel flats, several techniques have been applied to migrate the problems, including the following: • Pressurized spray rail cleaners. • Hi-rail based wire brushes. • Sander operations. • Grit-filled gels (sandite). Both NJ TRANSIT and SEPTA use high-pressure wash- ers. According to an NJ TRANSIT press release (12), New Jersey invested $420,000 in a device that sprays 17 gallons per minute at 20,000 psi spray using two 250-horsepower engines on a flatcar. In addition to spray cleaning, SEPTA also operates a gel/grit delivery system and manually placed compressed sand disks (“torpedoes”) on their system in peri- ods of severe weather. The Newark City Subway had previously tried a modified rail grinder to wire brush their rails, but the results were not satisfactory. Kumar reports similar ineffectiveness. How- ever, Metra regularly uses an engine-powered brush on its Electric District. Metra reports acceptable cleaning results. Metra also operates additional locomotives using sanders to clean the rails during severe weather conditions. Overseas use of special wheel-cleaning composite blocks was also noted. These are mounted on-board to clean tractive wheels and have led to higher train speeds, reduced wheel flats, and reduced train noise (8). Prevention is the most effective measure to reduce wheel slide. Training of operators is paramount; excessive traction and braking efforts are to be avoided. The transit systems sur- veyed indicate that automated slip-slide controls have greatly improved this situation. These modulate one or more control parameters such as service braking pressures, dynamic brakes, motor torques, and sanding. After employing such devices, wheel flats may be reduced by roughly 50 percent under normal conditions (11). This would translate into a 50 percent reduction in periodic wheel re-profiling costs. The technology and control systems need to be further improved or developed to minimize the wheel slide and wheel flat problem. 4.8 NOISE Every system but one expressed the recurring need for noise mitigation. Generally, noise problems fall into three categories: wheel screech/squeal, wheel impacts, and train roar. Wheel screech is usually caused by stick/slip oscilla- tions and transmitted via the wheel plate to the surround- ing air. Wheel impacts can be caused by wheel flats on smooth track or round wheels on special trackwork (e.g., crossing diamonds, switches). What is commonly

known under the umbrella of “train roar” is typically wheelsets bouncing on rails due to out-of-roundness or corrugated rails because of the difference (for most mate- rials) between a higher static coefficient of friction and lower dynamic coefficient of friction (13). Any technique to reduce this difference can be beneficial, such as lowering interface friction overall (lubrication) or employ- ing a friction modifier that reverses the typical (higher) sta- tic and (lower) dynamic coefficient relationship. In addition, since a wheelset that can generate the neces- sary RRD (via lateral shift) for a given curve will not require slip (creepage), wheel/rail combinations with good curving performance can reduce curving noise. Since lat- eral shift is affected by balance speeds, track gage, and guardrail clearances (if present), all these factors can pro- mote or impede noise creation. Note that on the very tight- est curves (less than 100-foot radius) seen during the sur- vey, no practical wheel profile could generate the necessary RRD. In these cases, the wheels will microscopically deform at the contact points, but only up to a point. The wheels will then oscillate between stick and slip conditions, as illustrated in Figure A-26. This is analogous to a dry- friction instability, and the wheel will in turn radiate offending noise at one or more of its bending natural fre- quencies. Lubrication could be the key solution to noise reduction on very sharp curves. Regarding immediate steps for mitigation of noise, the fol- lowing solutions have been implemented at the various tran- sit systems visited: • Maintaining wheels as round as possible. This includes both removal of flats and maintenance of roundness. Noise from wheel flats tends to be directly proportional to the flat size and increases with operating speed. • Lower creep forces via lower vehicle weights, wheel/rail lubrication or friction modification, or better curve negotiation. • Use of resilient rail fasteners. This is most effective when the actual offending noise source is not the wheels A-22 or rails but a secondary structure (e.g., girders) respond- ing to the dynamic forces transmitted out of the rails. • Use of resilient wheels or of ring dampers on solid wheels. • Adding sound absorption to stations and tunnels via sur- face treatments. This is not very effective at lowering noise levels, especially with ballasted track, which is already somewhat absorptive. Transit systems in gen- eral have reported mixed results after surface treat- ments. Such techniques should be carefully considered. Other elements that can reduce curve squeal discussed during the onsite surveys include resilient wheels, ring damped wheels, wheel taper, primary suspension stiffness, lubrication, restraining rails, gage widening, and curvature. Appendixes A-1 to A-5 discuss these topics. 4.9 FRICTION MANAGEMENT AND LUBRICATION Friction plays an important role in wheel/rail interface. It affects many wheel/rail interaction scenarios: • Wheelset steering • Truck hunting • Wheel/rail wear • Rolling resistance • Traction • Braking • Wheel flats • Wheel-climb derailment • Rolling contact fatigue • Noise The following are major benefits of applying a friction modifier or lubrication at the wheel/rail interface for transit systems: • Reduce wheel/rail wear. • Reduce wheel-climb derailment. • Reduce noise of wheel squeal. All transit systems surveyed have applied different types of wheel/rail lubrication techniques at some level. In general, commuter operations usually apply wayside lubricators on curves, especially sharp curves. Due to frequent braking and acceleration when approaching stations, the rapid transit and light rail operators have been more cautious when applying lubrication. Table A-7 lists the lubrication practice used by the transit systems surveyed. The Newark City Subway (light rail) has installed both wayside flange lubricators and top-of-rail friction modifiers. A relatively precise control of the amount of lubricant applied has been achieved based on the counts of wheel Figure A-26. Stick-slide occurred around the saturate region.

passes. NJ TRANSIT has reported successful noise reduction on sharp curves in the street and inside tunnels. Wheel sliding that could be induced by improper rail lubri- cation is a major concern for some transit systems, especially in city operations. Some of them have been limiting the application of any types of rail lubrication. Therefore, to receive the benefit from rail lubrication yet avoid the nega- tive effects, a highly structured friction management pro- gram is needed. The lubrication techniques need to be care- fully selected and thoroughly tested to meet specific requirements. The ideal friction management for transit oper- ations is to maintain a minimum level of lubrication to assure a smooth surface for the rail gage corner in curves, while avoiding over-lubrication, particularly at locations approach- ing stations and street crossings. Section 3.4 of the International Heavy Haul Associa- tion’s Guidelines to Best Practices for Heavy Haul Railway Operations: Wheel and Rail Interface Issues (6) describes different lubrication devices and techniques in detail. It also provides recommendations on lubrication practice. Although this book is focused on freight operations, some concepts in the lubrication section can be applied to transit operations. Transit operators may also need to establish guidelines that take into consideration the special features of their systems. A-23 4.10 WHEEL/RAIL WEAR Reducing wheel/rail wear and extending wheel/rail life is one goal that every system is making an effort to achieve. Wear cannot be totally avoided at the wheel/rail interface due to the steel-to-steel contact of wheel and rail under heavy load. However, wear can be reduced if the contact conditions are properly controlled. Wheel/rail wear is proportional to the energy dissipated at the wheel/rail interface. Therefore, the dissipated energy can be used to define a Wear Index. This is calculated from values of creep (γx: longitudinal, γy: lateral, and ωz: spin) and tangential force (Tx: longitudinal, Ty: lateral, and Mz: spin moment) in the contact patch for all wheels in a vehicle (Equation A-4). (A-4) The higher the Wear Index number, the greater the amount of wheel and rail wear. Equation A-4 indicates that wear increases with increased tangential forces, with increased creepages, or both. Figure A-26 shows that there are no creep forces (tangential force) or creepage in the pure rolling con- dition. The creep force increases as creepage increases until it achieves saturation. The creepage can continue to increase Wear Index T T Mx x y y z z n = + +( )∑ γ γ ω TABLE A-7 Track lubrication practice (the blank indicates no such service in that system) Light RailSystem Rapid Transit Commuter MBTA Limited wayside lubricators for back-of-flange and restraining rail. Others have been tested No information was received No information was received NJ TRANSIT Wayside flange lubricators, top-of-rail friction modifiers, and an onboard lubrication system are under testing. Wayside lubricators on curves. SEPTA Manually greased at very sharp curves Manually greased at very sharp curves. Wayside flange lubricators on curves over 3 degrees. WMATA No lubrication on mainline track. Some wayside flange lubricators are used in yards. Chicago Metra Wayside flange lubricators on curves. CTA Wayside flange lubricators on curves with radii less than 500 ft. A few trial wayside top-of- rail friction modifiers.

under the saturation condition. However, the resultant creep force remains the same. As discussed in the previous sections, poor wheelset steering on curves caused by improper wheel/rail profiles such as two-point contact, low RRD, cylindrical tread wheels, or independently rotating wheels can lead to higher creepages and higher creep forces and, hence, higher levels of wear. In addition to safety concerns, vehicle hunting on tan- gent track can produce much higher creep forces and creepages during wheelset yaw motion than during normal operation. Wheel sliding generates a saturated level of creep force and very high values of creepage to cause a very high level of wear in a short distance and the formation of wheel flats. The flats are often only a few spots on the wheel surface. However, in order to remove the flats, a considerable amount of material needs to be removed around the wheel diameter during wheel re-profiling. Wheel life can be significantly reduced if flats occur frequently. Generally, a wheel can only be re-profiled three to five times before reaching the thin rim limit. High contact stress, usually due to a small contact area, combined with high tangential forces can lead to a very high wear rate from plastic deformation of the material. High con- tact stress can also contribute to rolling contact fatigue (RCF). However, none of the systems surveyed indicated much concern with RCF. High friction at the truck center bearing can produce a high turning moment that resists truck steering on curves. Under normal vehicle and track conditions, the forces generated at the wheel/rail interface can overcome the resistance at the truck center bearing, but the higher force values will be asso- ciated with higher creepages and wear rate when truck cen- ter bearing friction is high (14). The design of trucks can also affect wear. Trucks with soft primary suspensions that allow the axles to steer in curves will generally have lower wheel-wear rates than trucks with stiff primary suspensions. However, if the primary suspen- sion is too soft, high-speed stability may be adversely affected. Further, any track irregularities can increase creep forces and creepages at the wheel/rail interface leading to higher wear. The following activities can reduce wheel/rail wear: • Optimization of wheel/rail profiles to improve vehicle curving and lateral stability and to reduce contact stress. • Reduction of friction at the truck center bearing. • Optimization of truck primary suspension to improve axle steering. • Improvement of track maintenance to reduce geometry irregularities. • Application of proper lubrication at the wheel/rail interface. A-24 4.11 PROFILE MEASUREMENT AND DOCUMENTATION Most transit systems use go and no-go gages to measure wheels and rails for making maintenance decisions. Only a few systems possess profile contour measurement devices. Without profile contour measurements, operation and main- tenance staff may not be aware of actual wheel/rail contact conditions. The following issues related to wheel/rail profiles have generally not been addressed and documented by the systems that were surveyed: • Initial contact conditions (new wheel contacting with new rail): – What is the initial contact pattern (severe two-point contact or conformal contact)? – What are the reasons that the specific wheel/rail pro- files were adopted? – What are the contact characteristics of new wheel and new rail? – Were any simulations or track tests performed to con- firm the positive performance of selected profiles? • Stable contact conditions (stable worn shapes of wheel and rail): – What are the shapes of stable worn wheels and rails? – How long does it take for the new wheel/rail to wear into the stable worn shapes? – How long does the stable worn shape last? – What are the contact characteristics of stable worn wheel and rail? • Contact condition of new trued wheels: – What are the contact conditions of new trued wheel contacting with stable worn rail? – What are the contact conditions of new trued wheel contacting with new rail if the trued wheel profile is different from the new wheel profile? • Contact condition of ground rail: – What are the contact conditions of ground rail con- tacting with stable worn wheels? – What are the contact conditions of ground rail con- tacting with new wheel if the ground profile is differ- ent from the new rail profile? • Critical contact conditions: – What are the worn wheel and rail profiles that may lead to flange climb or lateral instability? – What are the critical contact conditions in the system? Observations in the survey indicate that there is a need to produce improved guidelines for transit operations docu- menting the wheel/rail profiles and contact situations under different operating conditions. Maintaining wheel/rail system stability requires a clear maintenance objective in wheel/rail interaction. No ade- quate maintenance objectives can be defined without pro- file measurements, an understanding of the actual contact

conditions, and acknowledgement of wheel/rail wear progress and patterns. Practices that are only “based on experiences” are not likely to achieve a high level of effectiveness and efficiency in operation and mainte- nance, as compared to that based on a scientific under- standing of wheel/rail profiles and their effect on system performance. 4.12 IMPROVING UNDERSTANDING OF WHEEL/RAIL PROFILE AND INTERACTION The presentation related to wheel/rail profile and interac- tion that the research team made during the survey provided a fundamental understanding of wheel/rail interaction and related issues. It also provided a forum where vehicle and track maintenance staff could discuss the common problems associated with wheel/rail interaction. A-25 A 1-day seminar was also provided by the research team to a light rail system on the same topic with more detailed descriptions. Several staff members, including both man- agers and engineers, stated that they sometimes observed cer- tain scenarios on wheels or rails but did not understand the physics behind them, and sometimes they tried different ways to improve the situation based on experience, such as improving curving or reducing rail wear, but without solid scientific evidence. Improving the understanding through regular training or seminars on the topics related to wheel and rail profiles, wheel/rail interaction, and vehicle dynamics for transit employees (in particular, managers and engineers in mainte- nance groups) should be one strategic step in system improvement. With better understanding of the basic con- cepts of vehicle/track interaction, the operation and mainte- nance will be performed more effectively by making better decisions and selecting proper practices.

CHAPTER 5 CONCLUSIONS The following is a summary of common problems and concerns related to wheel/rail profiles and interaction in tran- sit operations identified by the survey conducted at six rep- resentative transit systems: • Adoption of low wheel flange angles can increase the risk of flange climb derailment. High flange angles above 72 degrees are strongly recommended to improve operational safety. • Rough wheel surface finishes from wheel re-profiling can increase the risk of flange climb derailment. Final wheel surface finish improvement and lubrication could mitigate the problem considerably. Introduction of new wheel and rail profiles needs to be carefully pro- grammed for both wheel re-profiling and rail grinding to achieve a smooth transition. • Without adequate control mechanisms, independently rotating wheels can produce higher lateral forces and higher wheel/rail wear on curves. • Cylindrical wheels may reduce the risk of vehicle hunt- ing, but can have poor steering performance on curves. • Some wheel and rail profile combinations used in transit operations were not systematically evaluated to ensure they have good performance on both tangent track and curves under given vehicle and track conditions. • Severe two-point contact has been observed on the designed wheel/rail profile combinations at several tran- sit operations. This type of contact tends to produce poor steering on curves, resulting in higher lateral forces and higher rates of wheel/rail wear. A-26 • Track gage and restraining rails need to be carefully set on curves to allow sufficient RRD and to reduce some high rail wear and lateral force. • Wheel slide and wheel flats occur on several transit sys- tems, especially during the fall season. Although sev- eral technologies have been applied to mitigate the problem, transit operators are in need of more effective methods. • Generally, noise related to wheels and rails is caused by wheel screech/squeal, wheel impact, and rail corruga- tions. Wheel/rail lubrication and optimizing wheel/rail contact could help to mitigate the noise problems. • Wheel/rail friction management is a field that needs to be further explored. Application of wheel/rail lubrica- tion is very limited in transit operation due to the com- plications related to wheel slide and wheel flats. • Reduction of wheel/rail wear can be achieved by opti- mization of wheel/rail profiles, properly designed truck primary suspension, improvement of track mainte- nance, and application of lubrication. • Without a wheel/rail profile measurement and docu- mentation program, transit operators will have difficulty reaching a high level of effectiveness and efficiency in wheel/rail operation and maintenance. • Further improvement of transit system personnel under- standing of wheel/rail profiles and interaction should be one strategic step in system improvement. With better understanding in their basic concepts, vehicle/track operations and maintenance will be performed more effectively.

REFERENCES 1. APTA Membership Directory, American Public Transportation Association, Washington, D.C., 2002. 2. Wu, H., and J. Elkins, Investigation of Wheel Flange Climb Derailment Criteria, AAR Report R-931, Association of Amer- ican Railroads, Washington, D.C., July 1999. 3. Nadal, M. J., “Locomotives a Vapeur, Collection Encyclope- die Scientifique,” Bibloteque de Mechnique Appliquee et Genie, Vol. 186, Paris, France, no date. 4. Parsons Brinckerhoff Quade & Douglas, Inc., TCRP Report 57: Track Design Handbook for Light Rail Transit, TRB, National Research Council, Washington, D.C., 2000. 5. APTA Passenger Rail Safety Standard Task Force Technical Bulletin, 1998-1, Part 1, American Public Transportation Association. 6. Guidelines to Best Practices for Heavy Haul Railway Opera- tions: Wheel and Rail Interface Issues, International Heavy Haul Association, May 2001. 7. Magel, E., and J. Kalousek, “Martensite and Contact Fatigue Initiated Wheel Defects,” Proceedings, 12th International Wheelset Congress, Qingdao, China, pp. 100-111, September 1998. 8. TCRP Research Results Digest 17: Improved Methods for Increasing Wheel/Rail Adhesion in the Presence of Natural Contaminants, TRB, National Research Council, Washington, D.C., May 1997. 9. Sun, J., et al., “Progress in the Reduction of Wheel Palling,” Proceedings, 12th International Wheelset Congress, Qing- dao, China, pp. 18-29, September 1998. 10. Tunna, J. M., “Wheel/Rail Forces Due to Wheel Irregulari- ties,” Proceedings, 9th International Wheelset Congress, Mon- treal, Quebec, paper 5-1, 1988. 11. Nelson, J., TCRP Report 23: Wheel/Rail Noise Control Manual, TRB, National Research Council, Washington, D.C., 1997. 12. “NJ Transit Unveils Aqua Track to Prevent Wheel-Slip Con- ditions,” New Jersey Transit press release, accessed via inter- net, December 2003. 13. Harris, C., and A. Piersol, Harris' Shock and Vibration Hand- book, 5th Edition, McGraw-Hill, pp. 5.19-5.20, and 40.6, 2002. 14. Wu, H., J. Robeda, and T. Guins, “Truck Center Plate Lubri- cation Practice Study and Recommendations,” Association of American Railroads, to be published. A-27

BIBLIOGRAPHY Brickle, B., TCRP Research Results Digest 26: Rail Corru- gation Mitigation in Transit, Transportation Research Board, National Research Council, National Academy Press, Washington, D.C., June 1998. Eadie, D., and M. Stantoro, “Railway Noise and the Effect of Top of Rail Liquid Friction Modifiers: Changes in sound and Vibration Spectral Distributions,” 6th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Gothenburg, Sweden, June 2003. Leary, “Railcar Train Track Dynamics Testing,” AAR Report P-93-109, Association of American Railroads Transporta- tion Test Center, Pueblo, Colorado, March 1993. Shabana, A., K. Zaazaa, and J. Escalona, “Modeling Two- Point Wheel/Rail Contacts Using Constraint and Elastic- A-28 Force Approaches,” Proceedings, IMECE2002 ASME International Mechanical Engineering Congress and Exposition, New Orleans, Louisiana, November 17-22, 2002. Booz Allen & Hamilton, Inc., TCRP Report 2: Applicability of Low-Floor Light Rail Vehicles in North America, TRB, National Research Council, Washington, D.C., 1993. Wickens, A.H., “Fundamentals of Rail Vehicle Dynamics, Guidance and Stability,” Swets and Zeitlinger, 2003. Wilson, Ihrig, & Associates, Inc., TCRP Report 67: Wheel and Rail Vibration Absorber Testing and Demonstration, TRB, National Research Council, Washington, D.C., 2001.

A-29 APPENDIX A1-1 MBTA The MBTA service district includes 175 cities and towns. MBTA operates 3 rapid transit lines, 13 commuter rail routes, and 5 light rail routes (Central Subway/Green Line). The information presented here relates primarily to light rail performance on MBTA’s Green Line. The Green Line is the nation's first subway. Service under Boston Common between Park Street and Boylston was inaugurated in 1897. Two types of light rail vehicles are currently operating on the Green Line: Number 7 cars from Japanese manufacturer Kinki Sharyo and Number 8 cars from the Italian manufac- turer Breda (Figure A1-1). Both types of cars are articulated at the center truck. Number 8 cars feature low floor platform level boarding for handicapped accessibility. Although deliv- eries began in 1998, MBTA’s acceptance of Number 8 cars remains incomplete due to various factors relating to the low floor technology’s sensitivity to the Green Line infrastructure. The information received on other MBTA lines is limited; it is discussed herein if it related to the subjects of this report. A1.1 WHEEL AND RAIL PROFILES By far, the most active wheel and rail profile discussions at MBTA relate to the Green Line. The wheel profile for both the existing Number 7 cars and the new Number 8 cars originally had a flange angle of 63 degrees. Combined with other vehicle and track factors, car performance in recent years has been a priority concern on the higher speed Riverside extension of the Green Line. These factors include fairly large lateral car body motions on the existing Number 7 cars and flange climb derailment on the Number 8 cars. The “low floor” center body of the Number 8 car is equipped with independently rotating wheels. Due to the absence of longitudinal forces in curving (as with any inde- pendent rotating wheels), the Number 8 mid-car axles pro- duce no steering moment for vehicle curving, which has resulted in large wheel AOAs. Combined with the low flange angle, the condition presents a risk of flange climb derailment. Prompted by a series of Number 8 car derailments, MBTA undertook a thorough review of the Green Line infrastructure and reevaluated both track and vehicle maintenance practices. At the time of this survey (late 2003), performance on the Green Line, including most notably elimination of the inci- dence of derailment of the Number 8 cars, had improved due to the change implemented in car and track maintenance. MBTA’s remedial actions included the following: • Where possible, rail profile grinding to remove the gage face lip and “serpentine rail wear” attributed to lateral motion exhibited by the Number 7 cars Figure A1-1. Number 7 and Number 8 type car. Number 7—Two Section LRV Number 8—Three Section LRV

• Closer attention to short wavelength track geometry perturbations (previously neglected due to 62-foot mid- chord offset criteria) • Implementation of an Interim Wheel Profile (IWP) with a flange angle of 75 degrees for the Number 8 cars The transition from the old wheel profile to the interim wheel profile with a higher flange angle was not without com- plications. Due to the limited capacity of wheel re-profiling and rail grinding, many Number 7 cars, which make up the majority of the Green Line car population, were still equipped with wheels with 63-degree flange angles (or slightly higher at worn condition). Some sections of worn gage face rail were still in use (with a gage angle of 63 degrees or slightly higher). These low angles on wheel flanges and rail gage faces contin- ued to resist the profile transition and cause fast wear of the few cars (10 to 20 cars) with 75-degree-flange-angle wheels. This high wear rate required very frequent re-profiling of these wheels (as low as 3,000 operating miles between re-profiling) in order to maintain the desired 75-degree flange angle. Further complications related to the wheel re-profiling machine installed at the Riverside shop, which is a milling- head type. Quick dulling of the wheel cutters required the cutter head to be re-indexed after re-profiling three cars. Re-indexing of the many cutting faces required 1 to 2 days of labor. This limited the shop capacity and further slowed down the transition to a higher and operationally stable wheel flange angle. Finally, the Green Line wheel tread design taper was 1:40, but recent worn-wheel profiles showed that the wheels con- sistently wore into a 1:20 taper. Thus, the IWP started with a more stable 1:20 tread taper to improve curving performance. MBTA’s current standard for rail profile installation is 115RE. A1.2 WHEEL LIFE AND WHEEL RE-PROFILING Previously, without a wheel re-profiling program for the Number 7 cars, wheels were condemned when they reached the thin flange limit. The average wheel life was about 18 months, or approximately 75,000 to 80,000 operating miles. During the IWP transition of wheel flange angle, wheels are being re-profiled every 2,000 to 3,000 mi to maintain the desired flange angle. The wheel can only be re-profiled three to five times before reached to the thin rim limit. Thus, the average life for these wheels was about 10,000 to 12,000 operating miles. Elsewhere at MBTA, wheel re-profiling is performed only based on wheel flat and thin flange criteria. A1.3 RAIL LIFE AND RAIL GRINDING At the MBTA, rapid rail wear on the tightest curves (e.g., the 75-foot radius, ∼76 degree, Bowdoin Loop on the Blue Line) allowed only 3 to 5 years between rail replacements. A-30 On such tight curvature, a practical wheelset cannot achieve the necessary RRD that would allow curving without exces- sive wear. To reduce flange climb risk and reduce wear, restraining rails were installed on any curve with a radius less than 1,000 ft (∼5.7 degrees). The restraining rail may further reduce the desired wheelset lateral shift that is required to produce RRD. Applying lubrication at the wheel/rail inter- face is a potential solution for reducing wear on tight curves. To accommodate the sensitivities of the Number 8 car and improve the Green Line track conditions in general, MBTA expended significant effort locating a grinding contractor that could remove the gage face lips on the LRV track. Only one vendor was able to rotate its stones to the necessary 75-degree angle. MBTA is gradually removing the lips where possible. However, the lack of stone clearance avail- able in guarded or girder rail means that it cannot be ground. These gage face conditions cannot be addressed without rail replacement. Therefore, the gage face lip will not be elimi- nated fully on the line for at least several years. The system does not have a programmed grinding effort for rail crown maintenance at this time. Limited rail grinding is performed only for solving immediate problems. For example, near Malden (Orange Line), noise and vibration complaints have been related to corrugations and resulting train roar. As a result, MBTA periodically grinds that section of rail to reduce train noise. A1.4 TRACK STANDARDS Improvements in track maintenance over the past 2 years have included grinding to remove the gage face lip (except where girder or guarded rails make this impossible) and attention to short wavelength track perturbations (previously missed due to 62-foot mid-chord offset criteria). MBTA has also focused more attention on using representative weights over track to provide loaded track surface measurements. This increased attention to track geometry maintenance is intended to improve LRV stability and ride quality and to reduce the Number 8 car’s higher derailment propensity. Because some MBTA rights-of-way were originally installed to accommodate earlier modes of public transporta- tion (e.g., horse-drawn streetcars), some locations preclude use of current track design standards. For example, in certain locations, there is no room for proper spirals between tangent and curves or between two adjacent curves. A1.5 FIXATION METHODS Although much track is conventional tie and ballast design, various direct-fixation track structures were also noted at MBTA. This included use of various direct-fixation fasteners on concrete roadbeds. Except for the extra costs, MBTA is pleased with the additional track isolation gained from such practices and with the longevity of the installations.

However, MBTA personnel related a few past experiences of premature concrete tie and/or direct fixation hardware deterioration. Two examples on the Red Line were men- tioned: one near the Harvard stop and one south of the JFK/UMass stop. Consequently, some removal of two-block concrete ties was performed. Also, it was felt that poor wheel roundness accelerated this deterioration. Since then, better maintenance of wheel flats has improved the situation. A1.6 LUBRICATION AND WHEEL SLIDE Limited wayside lubricators for back-of-flange and restraining rail lubrication are in use at MBTA. Directly lubricating the rail gage face or applying rail top lubrication or friction modifiers on tight curves have been or are being tested. Concerns that the lubrication may cause wheel sliding have slowed some implementations of rail lubricators. (Potential benefits are weighed against possible negative influences on braking distance—especially near platforms.) MBTA personnel reported that previous problems of operator-induced wheel slides have been largely eliminated with improved slip/spin control systems (e.g., automatic sanders). A1.7 NOISE MBTA has made considerable efforts to resolve occa- sional public complaints of noise and/or vibration. Various problem sources and solutions have been implemented as discussed below. On the Red Line, noise and vibration issues have occurred from the Park Street to St. Charles stops, near Harvard, and between the Savin Hill and JFK/UMass stops. Some of these issues could be traced to wheel flats. These have occurred more frequently on this line than the others (possibly due to heavier axle loads). As a result, MBTA is trying to gain a tighter control on wheel surfaces. The Park Street to St. Charles locations includes a subway- to-surface portal that leads the tunnel within just a few feet of residential foundations and basements. This section was reconstructed with a resilient ballast mat in the past, but fur- ther mitigation is planned using specialty fasteners. Similar retrofits have been applied between Savin Hill to JFK/UMass. A-31 The Harvard-to-Alewife extension was built with the intent of avoiding any potential noise and vibration com- plaints. As such, this section has rails over concrete slabs supported on neoprene disks. This provided 10- to 20-decibel reductions in groundborne vibration. This is a more expensive infrastructure than the use of the resilient fasteners mentioned above. Since the tunnel in this loca- tion is deeper than anywhere else within MBTA (about 130 ft deep at Porter), the earth itself provides an additional noise and vibration barrier. A1.8 MAJOR CONCERNS AND ACTIONS The most immediate concern on the Green Line at the time of the survey was accommodating the ongoing accep- tance of the low floor Number 8 cars and improving the sta- bility of existing Number 7 cars operating on the same line. This was being addressed through multiple, simultaneous efforts: • Increasing the maximum flange angle on the wheels. • Removing track serpentine wear and/or rail gage shelf (via rail replacement or gage face grinding). • Attending to shorter wavelength track geometry pertur- bations. • Replacing worn truck components on Number 7 cars. • Continuing investigation into potential design improve- ments to the Number 8 cars. Public perception of noise and vibration issues were a con- tinuing concern. As discussed above, various problem sources and solutions have been implemented, including the following: • Closer attention to removal of wheel flats and rail cor- rugation. • Resilient track mats. • Resilient rail fasteners. • Slab on isolator construction. MBTA is continuing to investigate more cost-effective remedies to improve the system performance and operating safety.

APPENDIX A-2 NJ TRANSIT NJ TRANSIT operations include three light rail transit sys- tems and a commuter rail system. The light rail systems are the Newark City Subway, the Hudson-Bergen System, and the River Line, connecting the cities of Camden and Trenton. The commuter system rail operation includes seven lines. This Appendix includes only information regarding the City Subway and the commuter operations. The following subsections will each address City Subway issues, followed by commuter operation topics. The Newark City Subway is a relatively short, light rail line of about 6 mi, built mostly on a previous canal right-of-way and operated for decades using President’s Car Commission (PCC) streetcars. The Hudson-Bergen line is a new light rail line. Both light rail lines now use the same type of vehicles from Kinki A-32 Sharyo (Figure A2-1), with low platform-level boarding and low floor features fully compliant with the Americans with Dis- abilities Act’s standards for accessible design. Wheel loads on these vehicles are approximately 12,000 pounds. Although both lines use the same general vehicle and sim- ilar resilient wheels, the wheel profiles are different due to previously existing infrastructure on the City Subway. Fore- sight in planning allowed the same truck, axle, and wheel plate configurations in both the City Subway and Hudson- Bergen applications. This was accomplished by specifying different tread widths and back-to-back flange locations on tires that mate similarly on the wheel plates common to the two light rail lines. The NJ TRANSIT commuter lines feature a mix of Gen- eral Electric Arrow III EMU electric cars and diesel-hauled Comet I-V cars made by Bombardier (Figure A2-2). These cars are all approximately 90 ft in length and have about a 15,250-pound wheel load. A2.1 WHEEL AND RAIL PROFILES A2.1.1 Light Rail Wheel profiles on the Newark City Subway follow an ORE (European Railway Organisation) standard, which is similar to the Pittsburgh LRV profile with a peak flange con- Figure A2-2. Commuter rail cars. Comet Type Car Arrow MU Type Car Figure A2-1. NJ TRANSIT city subway low floor LRV.

tact angle of 75 degrees and a 1:20 tread taper that provides for one point of contact with the 115RE rail installed on a 1:40 canted plate. The back-to-back dimension is 54.125 in. The flange top is flattened for lower contact stresses for the flange bearing frogs installed at the special trackwork. The Hudson-Bergen line uses an AAR-1B profile (75-degree flange angle) wheel design with 53.375 in. back-to-back spacing. Wheel diameter is 26 in. for both lines. The center truck of the LRV low-floor cars is equipped with independent rotating wheels. Due to dual articulation located outside the center truck boundaries, the wheels have a slight tendency to hard curving at the point of switch when the switch is in a diverging position and not properly adjusted. City Subway personnel have installed point protec- tions with housetops on all mainline turnouts to prevent wheel climbs. It has been observed that the wheels at the center truck have a higher wear rate compared to the end trucks due to a slight tendency to run against the low rail gage face in curv- ing. The wheel wear has been monitored using a MiniProf device to predict the interval before re-profiling. The standard Newark City Subway rail profile is 115RE, purchased in 1984 to replace 100RB. A2.1.2 Commuter Rail All NJ TRANSIT commuter cars operate on a common, 32-in. diameter wheel. The wheel profile is an AAR narrow flange with a 72-degree peak flange angle and 1:40 tread taper. In 1988, problems with vehicle lateral instability prompted NJ TRANSIT to replace the 1:20 taper with the 1:40 tread taper. Also, prior to 1999, the peak wheel flange angle was specified at 68 degrees. In the 1990s, a few low-speed flange climb derailments were generally attributed to unfortunate combinations of the following contributing factors: • Negotiating special trackwork • Dry rail • Newly cut wheels As a result, NJ TRANSIT commuter operation has since adopted a higher peak angle of 72 degrees. The profile transition period required approximately 1 year before all the wheels being seen in the shop had the steeper flange angle. NJ TRANSIT commuter operation has a MiniProf device. However, wheel profiles are generally only measured in such detail after a derailment or other serious incidents. On the NJ TRANSIT commuter operations, the current standard rail is AREMA 136 RE for new installations. Currently, 132 RE rail is still dominant throughout the sys- tem, and weights from 105 to 155 lbs./yd may also be found. A-33 A2.2 WHEEL LIFE AND WHEEL RE-PROFILING A2.2.1 Light Rail With only 2.5 years of operation on a new fleet of cars (at the time of this survey), the LRVs of the Newark City Sub- way had an average of only about 70,000 operating miles. Based on a MiniProf survey of every wheel, NJ TRANSIT extrapolations predict 7-year (200,000- to 250,000-mi) wheel/tire lives. The City Subway uses a lathe type wheel re-profiling machine. The first round of re-profiling may start after the cars reach an average of 100,000 mi of operation. A2.2.2 Commuter Rail NJ TRANSIT commuter engineers estimate a typical wheel life of 250,000 mi. Their wheel tread allows for about four turns during the wheel’s life. NJ TRANSIT commuter has two milling type re-profiling machines: one at MMC and one at Hoboken. In terms of capacity, four to eight cars can be re-profiled per shift per site. A2.3 RAIL LIFE AND RAIL GRINDING A2.3.1 Light Rail Rail on the Newark City Subway was all replaced in 1984. Some tight curves have shown more wear and have required replacement on a 5- to 6-year cycle. Restraining rails are installed on any curve with a radius less than 600 ft. On some very tight curves (60 and 80 ft in radius), a lip has formed on the inside rail. An initial attempt to lessen this wear pattern (by moving the guardrail for a narrower flange way) actually promoted the lip formation. NJ TRANSIT is now planning to increase the track gage to 57 in. and allow a 2-in. flangeway clearance between the stock rail gage face and the restraining rail on curves with 82-foot and 60-foot radii. It is expected better curving performance could reduce this wear. In several locations of 1984-era rail, some corrugations remain as created by the PCC cars operating before 2001. However, based on NJ TRANSIT evaluations, the new light rail vehicles appear to be flattening these waves. Per- haps this is related to the different traction system on the new cars, but it may also be related to different responding wavelength of the vehicles. NJ TRANSIT plans to remove the remaining corrugations with a rail profile grinding project. A2.3.2 Commuter Rail NJ TRANSIT commuter lines have about 900 curves with the tightest being sharper than 10 degrees (∼570-foot radius).

Rail wear was mentioned as an issue for a few curves. In these cases, rail life may be as short as 6 years. Two exam- ple scenarios were discussed: • At a grade crossing near Gladstone, the curve is elevated to 1.5 in. underbalance (designed for 45 mph traffic), but traffic actually operates around 25 mph due to the crossing. This results in faster low rail wear and some track movement. • Some sharper curves, which would normally receive flange lubrication, have no lubricators installed due to other concerns such as losing traction or braking capa- bility on a grade. NJ TRANSIT commuter operations report no programmed rail profile grinding operations. Limited spot grinding is used to return the rail shape to a new profile, but it is not generally targeted toward specific rolling contact fatigue issues. Newly installed rail is commonly ground after 1 year to remove sur- face defects or corrugations. Approximately twice a year, an ultrasonic and induction rail inspection is conducted across the system, uncovering 8 to 15 defects each time. Neither rail shelling nor corrugations are significant issues. A2.4 TRACK STANDARDS Track Geometry Standards (known as MW4) are mainly used by the commuter rail system and are used as a guide for the Newark City Subway. City Subway staff report that City Subway follows much tighter classifications for its operation than FRA would prescribe. For example, the light rail track gage dimension is a nominal 56 1/2 in., with a +1/4 in. and −0 in. tolerance, and the maximum operating speed is 50 mph. The FRA standard for commuter rail gage is a nom- inal of 56 1/2 in. with a +1 in. and −1/2 in. tolerance for speeds above 60 mph. The Newark City Subway experienced a derailment dur- ing turnout negotiation on a Number 10 Samson switch. It has been determined that the AREMA 5200 detail at the Samson type switch and the quality of point adjustment to the stock rail was not adequate and may always create a hazard. Consequently, housetop point protection was retrofitted to all switches. FRA track geometry standards apply on the NJ TRAN- SIT commuter lines. The National Railroad Passenger Cor- poration (Amtrak) track geometry car is currently used across the system quarterly. The Amtrak inspections of the 550-mi track typically yield about five to eight track geom- etry defects. NJ TRANSIT intends to perform 8 to 10 inspections per year. Programmed surfacing is performed on a 5- to 10-year interval and tends to follow the tie replacement cycle. A-34 A2.5 FIXATION METHODS The Newark City Subway currently uses wood ties on bal- last, except in stations where dual block wood is set in con- crete. A planned service extension will be near both an his- toric church and a performing arts center. Therefore, a floating slab design has been specified to reduce noise and vibration. The cost of this is estimated to be three to five times that of conventional track. The commuter operations at NJ TRANSIT use conven- tional wood tie/cut spike construction with premium fasten- ers on some curves. That is, curves greater than 2 degrees (∼2,900-foot radius) are gradually being re-fit with Pandrol fasteners and lag screws. Previously, NJ TRANSIT used hairpin-type fasteners in the curves, but the fasteners did not hold. A2.6 LUBRICATION AND WHEEL SLIDE A2.6.1 Light Rail The Newark City Subway applies a variety of rail lubrica- tion methods in its system. Wayside flange lubricators and wayside top-of-rail friction modifier systems are operating, and an onboard lubrication system is currently under test. In the yard there are eight lubricators using regular grease for the flange side and the back of the wheel. Wayside top-of-rail friction modifiers have been installed at the 60-foot and 82-foot curve radius turnaround loops at Penn Station (tunnel) and at the 100-foot radius (outdoor) curve at Franklin Street. Site inspections confirmed that no wheel screech was perceived at these locations. NJ TRAN- SIT reports no adverse effects of weather on the vehicle per- formance using the friction modifier outdoors. A concern for the Subway during autumn and spring is the so-called “black rail,” a slippery condition caused by falling leaves combining with morning dew and dust. When wet, the leaves are smashed by passing wheels and become a low- friction contaminant. This black rail condition can cause adhesion and braking problems systemwide. Efforts were made to improve the resulting low friction conditions via track cleaning with an electric rotating brush, but NJ TRAN- SIT did not report success. Rather, the brushing operation tended to merely distribute the contaminant evenly across the rail. Since then, NJ TRANSIT has procured a hi-rail water jet cleaner operating at 20,000 psi with much improved results. A2.6.2 Commuter Rail About 80 wayside lubricators are installed on the com- muter rail system curves. There is an ongoing debate within NJ TRANSIT about the minimum curvature that should receive a wayside lubricator. A systemwide review of rail profiles and lubricator placement is underway.

As mentioned previously, some curves that would nor- mally receive flange lubrication have no lubricators installed because of other concerns, such as losing traction or braking capability on a grade. Leaf residue on the tracks is also a seasonal problem for the commuter operations. A2.7 NOISE Noise and vibration is an important issue for the Newark City Subway, especially for the rail sections that are close to resi- dential areas. NJ TRANSIT has oriented some of their rail lubri- cation efforts to reduce noise levels as well as wear. At a turn- around curve (82-foot radius) in the Vehicle Base Facility yard and a few other locations, the wayside flange lubricators are used to reduce wheel squeal and wear. A similar success has been implemented at a sharp, in-street curve at Franklin Avenue via a wayside top-of-rail friction modifier. Also recently, squeal noise has been reduced underground at the sharp Penn Station curve via a top-of-rail friction modifier. As mentioned, the Newark City Subway is also making efforts to improve vehicle curving by properly adjusting rail gage and flange way clear- ances, which should also reduce the noise on curves somewhat. Unlike the City Subway, noise has not been an important issue on the NJ TRANSIT commuter operations. This is expected, given that commuter systems often operate with greater separation from residential and business areas. A2.8 MAJOR CONCERNS AND ACTIONS A2.8.1 Light Rail As a newly updated system overall, the Newark City Sub- way is maintaining a high level of operational quality with extensive efforts toward preventative maintenance. Both rail A-35 and wheel wear are being closely monitored, as evident by the use of MiniProf data from every wheel. Various existing mitigation techniques oriented toward wear, noise, and safety have been implemented: • Wayside flange lubrication. • Wayside top-of-rail friction modification. • Special trackwork point guards. • Optimization of restraining rails on curves. Additionally, prototype onboard flange lubrication is being tested and a program of preventative rail profile grind- ing is planned. A2.8.2 Commuter Rail NJ TRANSIT’s commuter rail wheel/rail profile mainte- nance is an ongoing process. Daily flange width and wheel flat inspections, as well as suitable capacity in the two wheel re-profiling shops result in good maintenance of wheel tread profiles. Past problems and solutions for the NJ TRANSIT com- muter system have included the following: • Vehicle hunting—reduced by implementing 1:40 tread tapers. • Low-speed flange climb at special trackwork— improved by implementing higher flange angle wheels. • Slow-speed derailments in yards (especially with newly cut wheels)—reduced by giving greater attention to yard track quality. • Low-speed flange climb when local operations are con- siderably below the designed balance speed—reduced by reengineering elevations at some curves.

APPENDIX A-3 SEPTA SEPTA has a very diverse infrastructure with operations including commuter, rapid transit, and light rail. Both the City Transit (Green Line) and Suburban Light Rail Lines (Routes 101 and 102) use similar 50-foot long Kawasaki LRVs. However, the wheel profiles and track gage are different between the city and suburban lines. SEPTA’s three rapid transit lines are the Market-Frankford (Blue) Line, the Broad Street Subway (Orange), and the Norristown Route 100 (Purple) Line. The Blue line oper- ates 55-foot long Bombardier M-4 stainless steel cars. The Orange Line has a fleet of Kawasaki B-IV cars each 67.5 ft in length. The Purple Line (Route 100) has a fleet of N-5 cars from Bombardier. Regarding commuter operations, the majority of SEPTA vehicles are 85-foot long Silverliner type vehicles from Budd, St. Louis Car, and GE. Other types of commuter cars include 85-foot electric push-pull cab cars and coaches from Bombardier. A3.1 WHEEL AND RAIL PROFILES The diameter of all LRV wheels is 27 in. The wheel pro- file for the LRV cars on the Green Line has a 63-degree flange, a 1:20 tread taper, and a flat top flange that may help to reduce the contact stress as wheels pass special flange- bearing trackwork. A cylindrical tread wheel profile is applied on the LRV cars operating on Routes 101 and 102. This wheel profile was inherited from previous cars. Analyses of tolerances for the flange root width show this to have a peak flange angle that is between 60 and 65 degrees. When new, these cylindrical wheels tend to wear quickly to a slightly hollow tread, as shown in Figure A3-1. They then stabilize to a reasonably constant shape. Field observations of tangent tracks on the Route 101 indicated a narrow contact band, skewed some- what towards the gage face of the rail. The light rail lines use 100RB rail. The rail gages are wider (ranged from 62.25 to 62.5 in.) than standard gage of 56.5 in. On the Orange (Broad Street Subway) Line cars, 28-in. wheels are used with a 63-degree flange angle and a 1:20 tread taper. Except for the commuter rail lines, the new rail laid are 115RE . However, former rail standards have left 80- to 100-lb/yd rail in some sections. A-36 The regional (commuter) line cars use 32-in. diameter wheels with 75-degree peak flange angle and 1:20 taper. The current rail standards for the commuter rail system are the 115RE and the 132RE. A3.2 WHEEL LIFE AND WHEEL RE-PROFILING The light rail lines (including the Norristown route) achieve about 150,000 to 200,000 mi between re-profiling. The average wheel life is about 10 years. The City Transit LRV (Green Line) wheels are generally re-profiled due to flange issues. Field inspections showed that these wheels often encounter street debris in the girder rail flangeway. As such, they experience excessive riding on the top of flange. The 101/102 LRV wheels are re-profiled at about a 5-year interval, based on a predicted usage of 33,000 mi per year. SEPTA has two re-profiling machines, a lathe type re-profiling machine and a milling-head re-profiling machine. The lathe machine has a single-point cutting tool that produces a smoother surface finish compared to that from the milling machine. The milling machine has a cutting head with many small cutters (staggered to form the wheel profile). SEPTA expressed particular interest in any potential flange climb effects caused by smoothness differences between left and Figure A3-1. SEPTA cylindrical wheel wears into slightly hollow but stable shape on Suburban Route 101, LRV.

right wheels on the same axle. Such differences have been seen when using one sharper cutting head and one dull head. The SEPTA wheel diameter tolerances after re-profiling 1/8 in. within the same axle, 1/4 in. axle-to-axle in the same truck, and 1/2 in. truck-to-truck difference in the same car. As with all the systems visited, SEPTA has experienced low-speed derailments, and almost all of them were flange climbs in yard tracks. Some of these were associated with newly re-profiled wheels. Wheel surface roughness after wheel re-profiling, combined with SEPTA’s low flange angles, could considerably reduce the L/V limit ratio required for wheel climb. On the commuter lines, operating miles are not tracked and therefore wheel lives are not known. Generally these wheels are trued for flat spots caused by braking and/or rail contaminants. A3.3 RAIL LIFE AND RAIL GRINDING Rail lives vary from 6 years (tighter curves) to 40 years (tan- gent track). Curves over 5 degrees (∼1150-foot radius) tend to wear quickly and are typically replaced within 5 to 7 years. On the rapid transit lines, fast wear in some tangent areas can be attributed to significant use of track brakes under the cars. Alternating gage face wear between left and right rail was reported at a certain locations. The causes are still under investigation. As shown in Figure A3-2, the rail at certain sections of the Green Line had significant wear or surface damage. The damage is likely caused by wheel impacts upon street debris in the girder rail flangeway. This can locally lift the tread contact and cause wheel impacts at an adjacent section. For the wide gage light rail lines, SEPTA owns an 8-stone grinding machine. Rail profile grinding is targeted toward producing an 8-in. rail head crown radius. A-37 For standard gage lines, contractors are used for infrequent grinding. SEPTA now replaces rails in tunnels when profile or surface problems are advanced. During recent experience with rail grinding in a tunnel, it was found that the spread of grinding dust, air contamination, and expensive station cleanup made rail grinding in those areas unfeasible with the available equipment. SEPTA reported that asymmetric grinding on some curve sections successfully improved vehicle curving and resulted in reduced wear and noise. Like other transit systems, SEPTA has had track corruga- tion problems at specific locations. Rail grinding is required periodically in these zones to remove severe corrugations. A3.4 TRACK STANDARDS Commuter rail lines follow FRA track safety standards. The light and heavy rail track is maintained to SEPTA inter- nal track standards. In brief, SEPTA track geometry stan- dards are similar to the FRA standards, although oriented toward 31-foot mid-chord lengths. (Gage specifications are equal to the FRA rules. Alignment specifications are under 1/2 in. of the FRA allowances. Vertical profile and cross level rules are similar to the FRA rules, and the track twist rules are slightly under the FRA allowances.) Light rail lines are designed to 4.5 in. maximum under- balance. All other lines allow up to 3 in. underbalance. Head- hardened rails are installed on curves. Guardrails are installed for rapid transit curves wherever tighter than 750 ft in radius. To improve vehicle curving and to reduce gage face wear of the high rail on tight curves, track gage is intentionally widened up to 1 in. in places. However, SEPTA has concerns about how much worn rail conditions effect the optimum effective gage on different curvatures. Figure A3-2. Rail surface damage on Green Line.

Regarding commuter operations, a track geometry car inspects track every third month. Walking track inspections are performed once a week for sections having less than 5 million gross ton (MGT) traffic per year and twice a week for sections having traffic more than 5 MGT per year. Various maintenance intervals are used on the light rail and rapid transit lines (including limited cross tie and rail replacement, and surfacing where necessary). As a long-term goal, SEPTA is planning to achieve the track standards one class higher than the FRA specification. A3.5 FIXATION METHODS Rail fixation for the various SEPTA rapid transit lines ranges from direct fixation (e.g., wood half-ties set in con- crete) to wood ties on ballast (at grade and elevated track). Light rail lines also have areas of direct pour concrete fixa- tion. In these cases, the rails are initially held in place every 6 ft with Pandrol clips and a steel beam tie. Then, the rails are fully embedded in concrete with only gage face clearance left in the concrete. However, tracks with this installation method show that the concrete can rupture prematurely near battered joints. For commuter track, both wood ties on ballast and booted two-block concrete ties are used. A3.6 LUBRICATION AND WHEEL SLIDE Rapid transit operations include up to 40-degree (150-foot radius) curves. Such curves are manually greased daily. SEPTA is hoping to improve flange grease controllability and efficiency on these curves by installing through-holes on the restraining rails, along with grease fittings and automatic pumps. On the commuter lines, most curves over 3 degrees (∼1900-foot radius) have wayside flange lubricators. The commuter lines include 12-degree (∼480-foot radius) curves near a regional station. This location formerly caused excessive wheel and rail wear. Now liberal rail greasing and 15 mph speed restrictions are used to mini- mize wear. Slippery rails due to leaf residue in the fall months are a major concern. In the fall, 60 to 80 percent of regional train delays are leaf-related. In 2002, this issue caused the delay of 2,357 trains. Wheel slides due to rail contamination lead to flat spots. Dynamic impacts due to these flats can damage the track, induce noise, and affect ride quality. To mitigate the seasonal problem, SEPTA cleans the track on the Norristown line, and on regional lines during their short, 3-hour overnight work window. This is done with both advanced techniques (former locomotives now called “Gel Cars” with a 5,000-psi high-pressure washer and traction gel applicators operating at 10 mph) and more tra- ditional methods, such as by applying sand with locomo- A-38 tives, and by manually placing small solid disks of com- pressed sand on the rail head. A new, speed-sensing , dynamic braking control system is being implemented in the rapid transit operation to reduce wheel sliding during braking. A3.7 NOISE The rapid transit lines (Market-Frankford and Broad Street) and the City Transit light rail lines converge under the Philadelphia City Hall. This array of tunnels and stairwells is excessively noisy due to the combinations of squeal, flang- ing noise, wheel impacts, and rolling noise. The Broad Street cars are subjectively deemed to be quite noisy, although it is believed that they were somewhat qui- eter when new. At least one subway station was retrofitted as a means of noise reduction. However, the noise level was not satisfactorily reduced in this station, even after the additional wheel/rail smoothing, sound absorption, and barriers. Atten- tion to this issue continues, because the root problem source remains somewhat undefined. The eastern portion of the Market-Frankford (Blue) line has required significant rail head and gage face grinding to remove corrugations (and associated noise) on tangents. The City Transit (Green) line has flange-bearing wheels for special trackwork. The route has one nonflange bear- ing frog with level points and wings. A depressed point frog was installed at one location, but immediate public complaints resulted in replacement with a level style. Dy- namic braking also tends to reduce noise by reducing wheel sliding. A3.8 MAJOR CONCERNS AND ACTIONS SEPTA inherited a wide array of infrastructure from pre- ceding entities. This includes different track design stan- dards, different vehicle types, and different track gages. SEPTA also inherited problems resulting from deferred maintenance by previous railroads. At one point, over 600 defective welds were found in track as a result of poor weld- ing practices. This number has steadily decreased as SEPTA continues to put forth significant effort into improving track maintenance. Similarly, the regional commuter lines were taken over in 1982 with immediate track geometry and rail condition problems, requiring several years of continuous improve- ment of track geometry to achieve desired quality condi- tions. Over the past 20 years, almost all tracks in the com- muter rail system have been upgraded with continuously welded rail. Lubrication continues to be an area of development at SEPTA. Rail wear issues primarily drive this effort. Although still employing manual track greasing in some rapid transit locations, more advanced track-based systems

are slowly being implemented. The next step in this process is a trial installation of through-hole grease fittings on guardrails for flangeway lubrication. SEPTA has experienced infrequent derailments that fall into two categories: train handling (traction, braking, exces- sive speed) and slow-speed flange climb (at more severe curves, yards, climbing switches, and sometimes soon after re-profiling). A-39 Wheel sliding and the resulting wheel flats are a major issue and problem, especially during the autumn season. Sev- eral techniques have been applied to ease the problem, but the need for developing more effective technology to remove rail contaminants is needed. The cause of rail corrugation is still under investigation. Both rail grinding and rail replacement have been conducted to remove corrugation.

APPENDIX A-4 WMATA WMATA has a large degree of standardization. Only three car types have been used in the system’s 35-year history: the original Rohr cars are still in use, as well as Breda cars pur- chased in the early 1980s and CAF cars recently delivered. The Rohr cars have an Atchison/Rockwell suspension with good curving performance. This type of car is deemed slightly more prone to hunting when trucks are worn. The Breda cars have a longer wheel base (5 in. longer) than Rohr cars, and a slightly stiffer primary suspension. Over time, the Breda cars have been involved in a few flange climb derail- ments. The cars have approximately 13,200-pound maxi- mum wheel loads and use 28-in. diameter wheels. (The weight of the Breda is approximately 81,000 pounds.) WMATA is a relatively new system compared to the other transit systems surveyed. Therefore, its track layout contains fewer tight curves. The tightest curve in WMATA has a radius of 250 ft (∼23 degrees). An extensive preventative maintenance program results in good ride and operational qualities. However, a few recent incidents of flange climb derailments have raised concerns related to wheel profiles and track gage. A4.1 WHEEL AND RAIL PROFILES The original WMATA cars were supplied with cylindrical wheel profiles that resulted in excessive wheel and rail wear. To reduce the excessive wear, a field experiment was per- formed during 1978 and 1979 to select a wheel profile with better wear performance. The wheels in 12 trucks of three Rohr car series were machined to various wheel profiles. Wear rates were analyzed. This test led to the adoption of the “British Worn” profile as WMATA’s standard wheel shape. This profile has a flange angle of 63 degrees. In recent years, there have been several incidences of flange climb derailment—most of them at yard switches. Generally, these derailments were caused by multiple factors. Among the derailment factors, observations included newly re-profiled wheels and dry rails. Under such conditions, the friction coefficient between wheel and rail can be quite high. In combination with WMATA’s low flange angle, the L/V ratio limit before precipitating a flange climb derailment can be considerably low. Also, wheels with low flange angles have less tolerance to any unexpected track irregularities. A-40 To improve margins of safety, WMATA is considering a design wheel profile change to a higher flange angle. How- ever, the system stability during such a transition is being carefully considered. The current standard rail is 115RE for new installation. Head-hardened rail is installed on tight curves. A4.2 WHEEL LIFE AND WHEEL TRUING WMATA wheels show a typical life of about 400,000 mi, or 4.5 years of operation. Between 3 and 5 re-profiling oper- ations are possible before reaching to the thin flange or thin rim limits. As with every system, wheel flats can be a prob- lem during the fall season each year. The autumn leaves are a major cause of wheel re-profiling. This has periodically overloaded the wheel shops, requiring a few weeks of over- time labor to remove flats. WMATA has two types of wheel-re-profiling machines: milling and lathe. Shop personnel report significantly smoother finishes with the lathe machine. Consequently, after the use of the milling type machine, WMATA wheels get a minimal pass as the final step of re-profiling (known as the “air cut,” where no significant material is removed). Perhaps more importantly, all wheels are now manually lubricated immediately after re-profiling. Wheel diameter tolerances after re-profiling are 1/16 in. within the axle, 1/4 in. axle-to-axle in the same truck, and 1/2 in. truck-to-truck in the same car. WMATA believes that most wheels are trued at least once per year as a result of its “no flat” policy. A4.3 RAIL LIFE AND RAIL GRINDING Generally, tangent track and most low rails at curves on this system have retained the original rails. Rail replace- ment is performed more frequently on sharper curves. WMATA allows 1/2 in. of gage face wear. Thus, the tran- sit system reports that curves greater than 7.5 degrees (∼760-foot radius) last 3 to 5 years, and frogs last about 8 years. Rails are not generally re-laid due to the extra effort required.

An outside contractor performs grinding annually. Loca- tions for rail grinding are specified based on subjective eval- uations of ride quality and noise. A4.4 TRACK STANDARDS Maximum speed on the system is 75 mph, but currently it is restricted to 59 mph for energy conservation and equip- ment longevity. Allowable track gage, alignment, profile, and cross level deviations tend to make up one-third to one-half of the toler- ances found in FRA rules for Class 3 (60 mph) track. Designed track gage also varies by curvature: • 1/4 in. tight on mainline tangent to 4-degree curves. • Standard on 4- to 16-degree curves. • 1/2 in. wide above 16-degree curves. • 3/4 in. wide above 16-degree curves with restrained rail. WMATA is installing guardrails on all switches corre- sponding to less than a 500-foot radius (∼11.5-degree). Also, curves with less than a 800-foot radius (∼7.2-degree) are equipped with guardrails. Guardrail clearance is set to 1 7/8 in. The sharpest yard curve is 250 ft in radius (∼23 degrees). The sharpest mainline track curve is 755 ft in radius (∼7.6 degrees). Secondary and yard tracks are designed to 4.5 in. underbalance operation. Tie plates are standard 1:40. WMATA has attributed some flange climbs on special track- work to the lack of rail cant. A4.5 FIXATION METHODS All WMATA surface tracks are crosstie on ballast con- struction. However, both elevated and underground tracks have direct fixation via resilient (rubber/steel tie pad) fasten- ers. Stiff (250-kip/in.) and softer (150-kip/in.) fasteners have been tried, with the softer versions preferred. A-41 A4.6 LUBRICATION AND WHEEL SLIDE No lubrication is performed on mainline track, but some traditional wayside flange lubricators are used in yard tracks and guard rails. Past trials of both on-board stick lubricators and wayside top-of-rail friction modifiers proved to reduce noise but caused wheel slide and were hard to maintain. Therefore operations precluded the application of lubrication on mainline. As with other lines, leaves are a problem in the fall caus- ing excessive wheel flats. WMATA does not attempt to clean rails; rather operating speeds are reduced and selected safety stops are used to reduce the effects of leaves. A4.7 MAJOR CONCERNS AND ACTIONS Major issues for WMATA relative to wheel/rail profiles are the following: • Improving wheel flange angle to reduce flange climb derailment. • Careful planning for a smooth transition to a new wheel profile. • Optimizing gage distance on curves to improve vehicle curving and reduce wear. • Searching for more effective techniques to deal with the leaf residue problem. • Applying resilient rail/tie isolators to reduce noise. • Investigating acceptable lubrication practices. • Maintaining a high level of ride quality. Infrequent and somewhat transient hunting has been known to occur at certain places on the system, which seems to be driven by specific combinations of vehicle and track (including prevailing grade). As the vehicles age, this hunting sit- uation may further deteriorate. If so, it is likely that a specific study of the cause/effect mechanisms will be required.

APPENDIX A-5 CTA CTA operates the city’s rapid transit system. Currently 225 mi of track are in service on seven lines, including about 25 mi of subway. CTA uses four series of 48-foot long passenger cars simi- lar in construction. These cars have a light axle load (19,200 pounds fully loaded) compared to other subway systems (around 26,000 pounds). All but the oldest CTA cars use a large kingpin (∼6-in. diameter and 14-in. length) allowing only rotational freedom about a vertical axis. All but the oldest cars have Wegmann style trucks, which equalize weight distribution by primary spring deflection and allowing the truck center plate to warp. Routine car inspections are conducted at 6,000 mi or 90 days. Partial overhauls are conducted at one-quarter life, or about every 7 years. Complete overhauls are performed at half life, or about 12 to 14 years. A5.1 WHEEL AND RAIL PROFILES CTA uses 28-in. diameter wheels with the AAR narrow flange cylindrical tread profile with a flange angle of close to 68 degrees. This profile was adopted by CTA in the 1930s to eliminate vehicle hunting that occurred at 60 to 80 mph on high-speed, interurban cars. Based on CTA’s staff statement during the survey, this cylindrical profile has been performing well, likely because of two major factors: • A high percentage of tangent track. • A lighter axle load compared to other rapid transit. CTA personnel recalled no mainline derailments in recent history. At the 54th Street yard, a few wheel-climb derail- ments have occurred in the past decade. These occurred at a 100-foot radius curve installed without a guardrail. The track worked well for 3 years, then an alignment of two factors caused a few climbs on newly re-profiled wheels: • Acceptance of a new wheel re-profiling machine at the shop that might have increased the wheel surface rough- ness after re-profiling. • Malfunction of the curve lubricator on this section of track. A-42 The combination of these two factors could considerably reduce the L/V limit for flange climb on the tight curve that has a tendency to generate high lateral forces. Subsequently, a guardrail was installed and the lubricator has been regularly inspected. The current rail profile at CTA is 115RE. However, short sections of older 90- and 100-lb/yd rail are still in use. Although starting with a crown radius, these rails are maintained to a flat head. Rail wear patterns identified in the field indicate that this wheel/rail combination has a rather wide contact band at wheel tread and rail head region. A5.2 WHEEL LIFE AND WHEEL RE-PROFILING CTA has not experienced flange wear problems using the AAR cylindrical tread contour. The wheel life is not actually tracked in routine maintenance. Thus, the current wheel life is unknown, but it was estimated as longer than 3 years and perhaps as much as 6 to 7 years. CTA estimates that almost all wheel profile maintenance is done due to tread flat spots, mostly induced by operational causes such as braking, acceleration, and curving. Some flat spots may be caused by rail contamination, such as falling leaves. Subjective conditions for removing flats are mainly based on operator or public complaints. Since this is not a dimensional criterion, CTA personnel believe that a few flat spots approaching 2 in. in diameter can be found on the sys- tem. Occasionally, a wheel is re-profiled because it has exceeded the high flange limit. Wheel tread hollowing is rarely seen during wheel maintenance. Wheel re-profiling is performed on lathe-style machines only at the Skokie shop and one Blue Line shop. CTA finds that this type of machine holds diameter variations on an axle much closer than a cutting head machine (within 0.005 to 0.010 in. from left to right wheel after re-profiling). The current wheel diameter tolerances allowed after re-profiling are 3/64 in. within an axle (0.046 in.), 1 in. axle- to-axle in the same truck, and 1-in. truck-to-truck within the same car (i.e., using the same rule as above).

A5.3 RAIL LIFE AND RAIL GRINDING Rails on tangent track and shallow curves have a relatively long life, perhaps 50 years. Further, rails last about 15 years even on the very tight curves at the corners of Chicago’s famous Loop (89-foot radius). This is likely due to the low wheel loads, local rail lubrication, and low speeds (15 mph) allowed around the curves in the Loop. CTA does not experience rail shelling because of light axle loading. Rail grinding is performed using a “rail smoother” that uses flat stones to grind a surface parallel to the top of the tie plates. The light grinding (using 8 to 10 grinder passes) is used on the whole system once a year to smooth corrugations and other imperfections. New rails are installed with the original crown, and CTA smoothes the head about 1 year after installation. Typically after such smoothing, the rail needs no maintenance for another 4 years. Elevated track may require smoothing slightly more often. A5.4 TRACK STANDARDS Maximum speed on the CTA system today is 55 mph, with 15 mph limits on the tight (90-foot radius) Loop curves. The CTA track is generally designed to FRA Class 3 track geom- etry standards, but specifically applying the shorter 31-foot criteria. Also, CTA designs curves for a maximum of 4.5 in. of underbalance operation. Track geometry is not measured regularly. A contractor was hired to measure the system in the early 1990s, but track geometry measurement has not been conducted since then. Visual inspections are performed twice a week by track walkers. No out-of-face, ultrasonic rail head inspections are performed, but ultrasonic bolthole/joint inspections are reg- ularly scheduled. All curves with a radius of less than 500 ft have guardrails, with a 1 7/8-in. flangeway clearance. The guardrail continues 10 ft before and after the curve. Designed track gage is the standard 56.5 in., except an additional 1/4-in. of width on curves tighter than a 125 ft radius. Maintenance is performed when the gage exceeds 1 in. in width. A5.5 FIXATION METHODS On elevated track, rails are fixed to full width wood ties. In the subway, CTA employs mostly wood half-ties in con- crete. Some subway rails are held with coach screws, others with resilient fasteners. In and near the O’Hare Station, the track is directly fixed in concrete with resilient fasteners. CTA’s surface tracks and a small amount of tunnel track are ballasted, with the use of spikes gradually being phased out in favor of clips. To minimize dynamic car responses due to track stiffness variation at bridge approaches, CTA designed special 100-foot A-43 segments on either side of steel structures or bridges. Longer switch ties and closer-than-normal tie spacing were applied to create a stiffer support between the standard ballasted track and the elevated track. CTA has noticed instances of the high rail lifting in loca- tions that have greater than a 1 7/8-in. flangeway in a guarded curve. The greater flangeway width allowed higher lateral force against the high rail, and, consequently, the rail lifted from the tie plates. The rail was retained with standard cut spikes. The flangeway width was corrected to 1 7/8 in. and the problem was corrected. A5.6 LUBRICATION AND WHEEL SLIDE CTA uses both traditional wayside flange lubricators and a few trial wayside, top-of-rail friction modifier installations. Lubricators are installed on the curves with a radius of less than 500 ft. CTA track design personnel expressed interest in learning how different lubrication methods affect lateral forces. The close spacing of trains on the system prevents the use of a hi-rail vehicle lubricator. No onboard rail lubrication is used or planned at this time. An earlier field trial of onboard solid stick flange lubricants (using the Skokie Swift Line) was unsatisfactory. Regarding seasonal wheel slides, the Skokie Swift (Yel- low Line) and the Brown Line near the end of the line on bal- lasted track have received noise complaints due to wheel flats. These flats are deemed to be related to leaf residue and resulting wheel slips. Removal of wheel flats is the active program to mitigate these complaints. Other lines of the CTA system generally operate without leaf problems, likely due to two factors: • Mostly underground, elevated, or freeway-median oper- ating away from vegetation. • Seven-day, 24-hour operations. For these reasons, CTA does not have a rail-cleaning program. A5.7 NOISE Due to the extensive curve lubrication employed and cur- rent vehicle designs (lighter weights and relatively soft sus- pensions), CTA has reduced rail/wheel noise considerably in the past 25 years. CTA’s solid wheels are now equipped with damper rings as shown in Figure A5-1, which has signifi- cantly reduced the free vibration of the plate. Although the elevated structures remain rather noisy, fur- ther noise reductions are largely deemed impossible without reengineered support structures, since the steel girders are very effective noise amplifiers.

A-44 A5.8 MAJOR CONCERNS AND ACTIONS CTA’s wheel/rail profile maintenance focuses on keeping the wheels round and the rails smooth. Satisfactory vehicle designs have been proven over long periods, and CTA has no plans to change what works. Track installations and lubrica- tion methods continue to evolve gradually, with a conserva- tive policy toward trial installations. Past problems have included the following: • Vehicle hunting—improved by employing a cylindrical profile years ago. • Curve squeal/screech—improved by slightly soft pri- mary suspension trucks, light vehicles, rail lubrications, and lowered operating speeds. • Slow-speed yard derailments—leading to greater atten- tion on guardrail placement and lubricator maintenance. CTA track designers would also like a computer program that allows input of design parameters (e.g., curve radius, operating speed, underbalance, lubrication presence, profile) and pro- duces the expected lateral force ranges generated by the wheels. Figure A5-1. Steel damper on CTA wheels: The steel damper fits snugly into a groove on the field-side plate and reduces ringing considerably.

Next: Appendix B - Investigation of Wheel Flange Climb Derailment Criteria for Transit Vehicles (Phase I Report) »
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TRB’s Transit Cooperative Research Program (TCRP) Report 71, Track-Related Research, Vol. 5: Flange Climb Derailment Criteria and Wheel/Rail Profile Management and Maintenance Guidelines for Transit Operations examines flange climb derailment criteria for transit vehicles that include lateral-to-vertical ratio limits and a corresponding flange-climb-distance limit. The report also includes guidance to transit agencies on wheel and rail maintenance practices.

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