Locomotive Crash Energy Management Vehicle-to-Vehicle Impact Test Results

Llana, Patricia; Jacobsen, Karina; Stringfellow, Richard · 2020 · ROSA P / John A. Volpe National Transportation Systems Center (U.S.)

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Summary

This paper reports on the results of the first vehicle-to-vehicle impact test within a Federal Railroad Administration (FRA) research program aimed at improving locomotive crashworthiness. The study addresses the critical safety issue of "override," where the strong underframe of one vehicle climbs onto the weaker superstructure of another during a collision, compromising the occupied space. To mitigate this, the program developed two Crash Energy Management (CEM) components for retrofitting onto locomotives: a Push-Back Coupler (PBC) and a Deformable Anti-Climber (DAC). The primary objective of this specific test was to demonstrate that these integrated components work together to absorb impact energy and prevent override in a head-on collision scenario. The experiment was conducted at the Transportation Technology Center in January 2019. A CEM-equipped F40 locomotive, retrofitted with the PBC and DAC, impacted a stationary conventional F40 locomotive. The target impact speed was 21 mph, though the actual speed achieved was 19.3 mph. The test setup included extensive instrumentation, such as accelerometers, strain gages, displacement transducers, and high-speed cameras, to capture gross motions, local deformations, and the sequence of component activation. Prior to the test, finite element analysis (FEA) models were developed to predict the behavior of the CEM components and the test vehicles. The test results confirmed that the CEM system functioned as designed. Despite the lower-than-target impact speed, the PBC triggered properly, exhausting its 21-inch stroke, and the DAC engaged, crushing its upper tubes to absorb energy. The vehicles remained in-line with no derailment and no signs of override. However, the shear bolts connecting the sliding lug did not fail, meaning the sliding lug did not translate as originally predicted for this speed range; consequently, the DAC absorbed approximately 260 ft-kips of energy, slightly below the 300 ft-kips target. Post-test inspection revealed minimal, easily repairable damage to both locomotives outside of the designed CEM component deformation. Comparisons between the test data and pre-test FEA models showed good agreement after the models were updated to reflect actual test conditions, such as the open coupler state and lateral offsets. The updated models accurately predicted the timing of DAC impact and the force-crush behavior. The study concludes that the CEM system effectively manages crash energy and prevents override in vehicle-to-vehicle collisions. The findings validate the design concepts and support the continuation of the research program, which includes further vehicle-to-vehicle tests with different stationary vehicles and a final train-to-train collision test.

Key finding

The CEM-equipped locomotive successfully absorbed impact energy and prevented override during a 19.3 mph collision with a conventional locomotive, maintaining vehicle alignment without derailment.

Methodology

field_study

Sample size: 2

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• secondary collisions