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3 CHAPTER 1 INTRODUCTION The objective of this project was to improve wheel/ applying the management and maintenance of wheel/rail rail interaction in transit systems by introducing flange climb profiles for transit operators. derailment criteria and wheel/rail profile management Due to the diversity among practices currently applied by and maintenance guidelines that can be applied to transit different rail transit systems, it is not possible to set univer- operations. sal rules that can be applied to all transit systems. However, it will be beneficial to recommend certain guidelines that transit operations can follow in their wheel and rail mainte- 1.1 BACKGROUND nance practice. Thus, some guidelines in this report are rather more conceptive than quantitative. A railroad train running along a track is one of the most The contents of this report were compiled as the result of complex dynamic systems in engineering due to the many a review of the literature pertaining to flange climb derail- nonlinear components in the system. In particular, the inter- ment, wheel/rail interaction and wheel/rail profiles; exten- action between wheel and rail is a very complicated nonlin- sive research on the development of flange climb derailment ear element in the railway system. Wheel and rail geometries, criteria; the investigation on several representative transit involving both cross sectional profiles and geometry along systems; and the authors' experiences on a number of proj- the moving direction with varying shapes due to wear, have ects previously conducted in related fields. a significant effect on vehicle dynamic performance and operating safety. The wheel/rail interaction in transit operations has its own 1.2 STRUCTURE OF THIS REPORT special characteristics. Without the requirement for interop- erability, transit systems have adopted different wheel and This work was performed in two phases. In Phase I, the rail profile standards for different reasons. Some of these common problems and concerns related to wheel/rail profiles standards are unique to a particular system. Older systems were defined through a survey conducted on representative with long histories frequently have wheel and rail profile transit systems. The preliminary flange climb derailment cri- standards that were established many years ago. For some teria, derived using the wheel profiles collected in the transit older systems, the reasons that specific profiles were adopted system survey, were proposed. Two reports were produced have been lost in time. Newer systems have generally after the Phase I work and are presented as appendices: selected the wheel/rail profiles based on the increased under- standing of wheel/rail interaction in recent years. · Appendix A: Effect of Wheel/Rail Profiles and Wheel/ Transit systems are usually operated in dense urban areas, Rail Interaction on System Performance and Mainte- which frequently results in lines that contain a large percent- nance in Transit Operations, and age of curves or curves with small radii, which can increase · Appendix B: Investigation of Wheel Flange Climb wheel and rail wear and increase the potential for flange climb Derailment Criteria for Transit Vehicles (Phase I derailments. Transit systems also operate a wide range of Report). vehicle types--such as those used in commuter rail service, heavy or rapid transit, and light rail vehicles--with a wide Section 1.3 of this report briefly summarizes the results of range of suspension designs and performance characteristics. Phase I. Increasing operating speed and introducing new designs of In Phase II, the flange climb derailment criteria developed vehicles have posed an even greater challenge for transit sys- in the Phase I work were further validated by track test data. tems to maintain and improve wheel/rail interaction. A general form of the criterion is proposed in this report. Considering the special features of transit operations, the A report detailing the validation and development of the purpose of this report is first to propose a general form of flange criteria, "Investigation of Wheel Flange Climb Derailment climb derailment criterion derived from wheel profiles applied Criteria for Transit Vehicles (Phase II Report)," is attached in transit vehicles and, second, to provide the guidelines for as Appendix C.