Evaluation of dynamic and impact wheel load factors and their application in design processes

A sustained increase in heavy axle loads and cumulative freight tonnages, coupled with increased development of highspeed passenger rail, is placing an increasing demand on railway infrastructures. Some of the most-critical areas of the infrastructure in need of further research are track components used in high-speed passenger, heavy haul and shared infrastructure applications. In North America, many design guidelines for these systems use historical wheel loads and design factors that may not necessarily be representative of the loading currently experienced on rail networks. Without a clear understanding of the nature of these loads and how design processes reflect them, it is impossible to adequately evaluate the superstructure in order to make design improvements. Therefore, researchers at the University of Illinois at Urbana-Champaign are conducting research to lay the groundwork for an improved and thorough understanding of the loading environment imparted into the track structure using wheel loads captured by wheel impact load detectors. This paper identifies several design factors that have been developed internationally, and evaluates their effectiveness based on wheel loads using several existing and new evaluative metrics. New design factors are also developed to represent the wheel-loading environment in a different manner. An evaluative approach to historical and innovative design methodologies will provide improvements to designs, based on actual loading experienced on today's rail networks.