Performance of Passenger Rail Vehicles Under Blast Conditions: Testing and Modeling

The mission of the U.S. Transportation Security Administration (TSA) is protection of the nation’s transportation systems to ensure freedom of movement for people and commerce. In furtherance of its mission, TSA’s Office of Security Capabilities has contracted with Transportation Technology Center, Inc. (TTCI) and Arup North America Ltd (Arup) to conduct research to quantify the vulnerability of railcars and infrastructure to damage caused by the use of explosives. The main objectives of the ongoing research program are to develop tools to evaluate the performance of existing railcar structures, develop potential mitigation measures for current railcars, and investigate future advanced designs under blast conditions. TTCI performed a series of full-scale tests on three major passenger railcar types: light rail, commuter and transit. Test scenarios were developed based on extensive risk assessment and historical data. Tested scenarios include single internal charges in various locations, simultaneous internal charges and external charges on a station platform. Well instrumented tests provide experimental assessments of existing railcars’ blast performance and data for validation and refinements of finite element blast models developed by Arup. The blast models incorporate sophisticated computational fluid dynamics (CFD) modeling of blast events to predict blast wave propagation and pressure applied on the structure. Hitherto research has focused on the railcar structure. However the test series has provided information on damage to infrastructure, including rail, ties, ballast, and both catenary and third-rail electrification systems. The finite-element blast models will provide railcar designers the means to investigate the effects of blast mitigation measures and reduce the need for physical tests. Several mitigation measures were installed and tested to evaluate their effectiveness. One car was equipped with typical interior components including seats and partition walls. One side of the car was equipped with standard components and the other side with remedial components that are intended to mitigate the effects of a blast. A similar approach was used for windows. This configuration allowed direct comparisons and performance assessments of the blast mitigation measures. Companion modeling and finite element analysis (FEA) of the blast response of the railcar and interior components provided a computational tool by which mitigation measures may be assessed and refined. This paper summarizes recent research sponsored by TSA and conducted by TTCI and Arup on blast vulnerability of railcars and infrastructure to damage caused by the use of explosives.