Load Quantification for Light Rail, Heavy Rail, and Commuter Rail Transit Infrastructure

The type and magnitude of loads passing through the track superstructure have a great impact on both the design and the performance of concrete sleepers and fastening systems. To date, the majority of North American research focusing on quantifying rail infrastructure loading conditions has been conducted on heavy-haul freight railroads. However, the results and recommendations from these studies may not be applicable to the rail transit industry due to a variety of factors. Unlike freight railroads, which have standardized vehicle maximum gross rail loads and superstructure design practices, the rail transit industry is home to significant variety of vehicle and infrastructure designs. Some of the current transit infrastructure design practices, which were established decades ago, need to be updated with respect to today’s loading environment, infrastructure types, and understanding of component and system-level behavior. This paper focuses on quantifying the current load environment for light rail, heavy rail, and commuter rail transit infrastructure in the United States. As an initial phase of this study, researchers at the University of Illinois at Urbana-Champaign (UIUC) conducted a literature review of different metrics used to evaluate the static, dynamic, impact, and rail seat loads for rail transit infrastructure. UIUC will compare these methods and their computed values to determine which provide the most accurate estimation of the expected loading condition given a set of operating and infrastructure characteristics. Proper load quantification for rail transit systems, gained through an improved understanding of load path and rail seat load, will help to establish the basis for developing recommendations for a mechanistic design process for rail transit infrastructure components. Ultimately, the results from this research will allow transit agencies to increase the effectiveness of their capital spending and they have the potential to improve safety, ride quality, capacity, and the life cycle of rail transit infrastructure.