Locomotive Crash Energy Management Train-To-Train Impact Test Results
Authors: Llana Patricia , Stringfellow Richard , Jacobsen Karina 
Published: June 2024

Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Data, and Innovation (RD&I). Two crash energy management (CEM) components that can be integrated into the end structure of a locomotive have been developed: a push-back coupler (PBC) and a deformable anti-climber (DAC). These components are designed to work in unison to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of another vehicle, can be devastating and compromise the occupied space. These CEM components are specifically designed to mitigate the effects of a collision and to prevent override of one of the lead vehicles onto the other. They are designed to improve the crashworthiness of equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment.

In prior research, designs for the two CEM components for retrofit onto the forward end of a locomotive, a DAC and a PBC, were developed, fabricated, and tested. The tests were successful in demonstrating the effectiveness of the two CEM components. In a follow-on program, the two CEM components were integrated into the end structure of a conventional locomotive to demonstrate, through a series of full-scale vehicle collision tests, that these components work together to mitigate the effects of a collision and prevent override. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in coupling, vehicle-to-vehicle, and train-to-train tests.

In the first series of tests, both conventional and CEM coupling tests were conducted. The conventional coupling tests were conducted to establish the speed at which coupling does not cause damage to either of the colliding vehicles. The CEM coupling tests evaluated the performance of the PBC at collision speeds ranging from 2 mph to 9 mph. This test series allowed a performance comparison of a conventional locomotive with a CEM-equipped locomotive during coupling, as well as confirmation that the PBC triggers at a speed well above typical coupling speeds and at the designed force level.

The second series of tests comprised two vehicle-to-vehicle collision tests. In Vehicle-to-Vehicle Test #1 (V2VT1), a CEM locomotive impacted a standing conventional locomotive. In Vehicle-to-Vehicle Test #2 (V2VT2), a CEM locomotive impacted a standing consist led by an M1 cab car with trailing freight cars. The vehicle-to-vehicle tests were successful in demonstrating the effectiveness of the components of the CEM system working together as an integrated system to absorb impact energy and to prevent override in two different vehicle-to-vehicle collision scenarios. The computer simulations predicted the behavior of the equipment in both collision scenarios with high fidelity.

This paper describes the results of the final test in the test program, the Train-to-Train Test (T2TT). In this test, a CEM locomotive-led consist impacted a standing conventional locomotive-led consist. The primary objective of the test was to demonstrate the effectiveness of the CEM system in a consist, including managing load path, and inhibiting override and lateral buckling. Preparation for this test involved extensive computer simulations, repair of the CEM systems used in previous impact tests, and coordination of numerous research engineers, instrumentation engineers, and test engineers. The target impact speed was 21 mph. The actual speed of the test was 24.3 mph. The CEM system worked exactly as designed, successfully absorbing energy, keeping the vehicles in-line and the impact ends engaged, with no derailment and no signs of override. All test objectives were met, and test results compared favorably with pre-test analysis predictions as well as with post-test analyses run at the actual test speed. Equipment damage is described, and test results are provided and evaluated.