Locomotive Crash Energy Management Coupling Tests Evaluation and Vehicle-to-Vehicle Test Preparation

Llana, Patricia; Stringfellow, Richard; Jacobsen, Karina · 2019 · ROSA P / United States. Department of Transportation. Federal Railroad Administration. Office of Research, Development, and Technology

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Summary

This paper evaluates Crash Energy Management (CEM) components designed to improve locomotive safety by preventing vehicle override during collisions. The research, directed by the Federal Railroad Administration (FRA), focuses on two integrated components: a Push-Back Coupler (PBC) and a Deformable Anti-Climber (DAC). These systems are intended to manage impact energy and inhibit the strong underframe of one vehicle from climbing onto the weaker superstructure of another. The study addresses industry concerns regarding the potential for premature PBC triggering during normal service coupling, which could necessitate costly replacements. The methodology involves a series of full-scale dynamic tests and finite element analysis (FEA). First, conventional coupling tests were conducted to establish a baseline for non-destructive coupling speeds. Second, CEM coupling tests were performed using an F40 locomotive retrofitted with a PBC, impacting an M1 cab car at increasing speeds (2 to 9 mph) until the PBC triggered. The paper also details the preparation for the next phase: a vehicle-to-vehicle impact test where a CEM-equipped F40 impacts a stationary conventional locomotive. This upcoming test utilizes extensive instrumentation, including accelerometers, strain gages, displacement transducers, and high-speed cameras, to capture gross motions, load paths, and deformation sequences. Pre-test FEA models predicted system behavior at a target impact speed of 20 mph. Results from the coupling tests demonstrated that the PBC performs as designed. In conventional tests, damage to the M1 car began at 4 mph, with significant structural failure occurring at 10–12 mph. In CEM tests, the PBC did not trigger until an impact speed of 9 mph, well above the typical 2–4 mph coupling range and the 4 mph maximum recommended by the Association of American Railroads. The PBC triggered at a force of approximately 670 kips, consistent with predictions. Below 6 mph, impact forces for both conventional and CEM systems were nearly identical; above 6 mph, the CEM system limited loads until triggering. Structural damage to the M1 in CEM tests was less severe than in conventional tests at comparable speeds, attributed to lower impact velocities and the PBC’s load-limiting characteristics. The significance of this work lies in validating the serviceability and crashworthiness of locomotive CEM systems. The coupling tests confirmed that the PBC will not accidentally trigger during normal operations, addressing a key barrier to adoption. The paper outlines that subsequent vehicle-to-vehicle and train-to-train tests will further demonstrate the integrated system’s ability to absorb energy, prevent override, and maintain compatibility with various rail equipment. The data collected will also refine analytical models, ensuring accurate predictions of crash dynamics for future safety designs.

Key finding

The push-back coupler triggered at 9 mph, which is well above the typical coupling speed range of 2 to 4 mph, confirming it does not activate prematurely during service.

Methodology

mixed_methods

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