Liquefied Natural Gas Tender Crashworthiness Research

Research is being conducted to develop technical information needed to formulate effective natural gas fuel tender crashworthiness standards. This research is being performed for the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology, and intended to facilitate industry efforts to use natural gas as a locomotive fuel. Strategies to assure crashworthiness during moderate accidents, such as train-to-train collisions at speeds up to 40 mph, are being evaluated. This research applies the approach FRA has used to develop technical information on locomotive, hazmat tank car, and diesel fuel tank crashworthiness. There are four primary tasks: 1. Definition of collision scenarios 2. Evaluation of traditional designs 3. Evaluation of alternative designs 4. Recommendation of effective crashworthiness strategies The tender scenarios have been drafted from reviews of freight train accidents and of scenarios developed for locomotives, hazmat tank cars, and fuel tanks. From these reviews, five scenarios were selected. These scenarios are intended to bound the range of collisions that a tender may experience, are being used to evaluate the crashworthiness of traditional tender designs, and will be used to evaluate alternative design tenders. The five candidate scenarios are: 1. Train-to-train collision 2. Grade-crossing accident 3. Tender derailment and rollover 4. Impact into tender tank shell during derailment 5. Impact into tender tank head during derailment As part of previous research on locomotives and passenger equipment, a range of crashworthiness analysis techniques were developed. These include simplified techniques, which can be performed rapidly and provide essential results, and detailed computer simulations which provide a wealth of information. The crashworthiness performance of a hypothetical tender design has been evaluated using simplified techniques. Simplified techniques include quasi-static crush analysis of structural elements and lumped-parameter analysis of train dynamics. The results suggest that efforts to enhance crashworthiness should principally be directed toward the train-to-train scenario. Work is ongoing to develop strategies for improving tender crashworthiness. This research is being conducted cooperatively with the Association of American Railroads (AAR). The research results are being shared with the AAR’s Natural Gas Fuel Tender Technical Advisory Group (NGFT TAG). The NGFT TAG is developing industry standards, including crashworthiness requirements, for revenue-service natural gas fuel tenders. There is a companion paper which describes crashworthiness research sponsored by AAR, including detailed computer simulations of tender crashworthiness. This paper describes development of scenarios and simplified analyses of tender crashworthiness.