Locomotive Crash Energy Management: Train-to-Train Impact Test [Research Results]

Gordon, Jeff · 2023 · ROSA P / United States. Department of Transportation. Federal Railroad Administration. Office of Research, Development, and Technology

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Summary

This report details the results of a train-to-train impact test conducted by the Federal Railroad Administration (FRA) to evaluate Crash Energy Management (CEM) technologies for locomotives. The research addresses the critical safety issue of vehicle override, where the strong underframe of one vehicle impacts the weaker superstructure of another, potentially compromising the occupied space and causing devastating injuries. To mitigate this, the FRA developed two CEM components for retrofitting onto locomotive end structures: a push-back coupler (PBC) and a deformable anti-climber (DAC). These components are designed to work in unison to inhibit override and lateral buckling during collisions. The specific study reported here aimed to demonstrate the feasibility and effectiveness of these integrated components in a full train-to-train collision scenario involving conventional locomotives, passenger cars, and freight equipment. The experiment was conducted in August 2022 at the Transportation Technology Center in Pueblo, Colorado. A CEM-equipped F40 locomotive, retrofitted with the PBC and DAC and leading two M1 passenger cars, impacted a stationary conventional F40 locomotive backed by two hopper cars. The target impact speed was 21 mph, though the actual speed reached 24.3 mph. The test objectives included triggering the PBC’s complete stroke, activating shear bolt failure in the sliding lug, and ensuring the DAC absorbed at least 50% of its required energy capacity (300 ft-kips of the 600 ft-kips requirement). Researchers utilized high-speed video, accelerometers, and displacement sensors to monitor the collision, while finite element analysis (FEA) models were used for pre-test predictions and post-test validation. The test results confirmed that the CEM system performed exactly as designed. The PBC triggered at approximately 670 kips, deformed its full 21-inch stroke, and absorbed ~1,080 ft-kips of energy. Subsequently, the shear bolts failed, allowing the sliding lug to translate 10 inches into the draft pocket, transferring the load path to the DAC. The DAC crushed in a controlled manner, absorbing ~600 ft-kips of energy. Crucially, the system kept the vehicles engaged and in-line throughout the impact, resulting in no derailment and no signs of override. Post-test FEA results closely matched the physical test data regarding relative displacements and deformation patterns. While significant plastic deformation occurred in the colliding locomotives as predicted, the passenger cars sustained only minor damage, such as side wall rippling and draft gear failure, with no evidence of wheel lift. The study concludes that integrating CEM components into locomotives significantly improves crashworthiness by effectively managing load paths, absorbing collision energy, and preventing override. The successful demonstration of these components in a full train consist provides the FRA with critical data for evaluating alternative compliance standards for locomotive crashworthiness. Future actions include comparing these results with previous vehicle-to-vehicle tests and conducting further override studies to refine safety regulations.

Key finding

The Crash Energy Management system successfully prevented override and derailment while absorbing impact energy during a train-to-train collision at 24.3 mph, performing exactly as designed.

Methodology

on_road

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