Two full-scale impact tests were conducted to measure the crashworthiness performance of Crash Energy Management (CEM) passenger rail cars. On December 3, 2003 a single car impacted a fixed barrier at approximately 35 mph and on February 26, 2004, two-coupled passenger cars impacted a fixed barrier at approximately 29 mph. Coach cars retrofitted with CEM end structures, which are designed to crush in a controlled manner were used in the test. These test vehicles were instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of each car body in three dimensions, the deformation of specific structural components, and the force-crush characteristic of the CEM end structure.Collision dynamics models were developed to predict the gross motions of the test vehicle. Crush estimates as a function of test speed were used to guide test conditions. This paper describes the results of the CEM single-car and two-car tests and provides results of the structural test.The single-car test demonstrated that the CEM design successfully prevented intrusion into the occupied volume, under similar conditions as the conventional test. During both CEM tests, the leading passenger car crushed approximately three feet, preserving the occupant compartment. In the twocar test, energy dissipation was transferred to the coupled interface, with crush totaling two feet between the two CEM end structures. The pushback of the couplers kept the cars inline, limiting the vertical and lateral accelerations. In both the conventional tests there was intrusion into the occupant compartment. In the conventional two-car test sawtooth lateral buckling occurred at the coupled connection.Overall, the test results and model show close agreement of the gross motions. The measurements made from both tests demonstrate that the CEM design has improved crashworthiness performance over the conventional design.

On March 23, 2006, a full-scale test was conducted on a passenger rail train retrofitted with newly developed cab end and non-cab end crush zone designs. This test was conducted as part of a larger testing program to establish the degree of enhanced performance of alternative design strategies for passenger rail crashworthiness. The alternative design strategy is referred to as crash energy management (CEM), where the collision energy is absorbed in defined unoccupied locations throughout the train in a controlled progressive manner. By controlling the deformations at critical locations the CEM train is able to protect against two dangerous modes of deformation: override and large-scale lateral buckling.The CEM train impacted a standing locomotive-led train of equal mass at 31 mph on tangent track. The interactions at the colliding interface and between coupled interfaces performed as expected. Crush was pushed back to subsequent crush zones and the moving passenger train remained in-line and upright on the tracks with minimal vertical and lateral motions.The added complexity associated with this test over previous full-scale tests of the CEM design was the need to control the interactions at the colliding interface between the two very different engaging geometries. The cab end crush zone performed as intended because the locomotive coupler pushed underneath the cab car buffer beam, and the deformable anti-climber engaged the uneven geometry of the locomotive anti-climber and short hood. Space was preserved for the operator as the cab end crush zone collapsed.The coupled interfaces performed as predicted by the analysis and previous testing. The conventional interlocking anti-climbers engaged after the pushback couplers triggered and absorbed the prescribed amount of energy. Load was transferred through the integrated end frame, and progressive controlled collapsed was contained to the energy absorbers at the roof and floor level. The results of this full-scale test have clearly demonstrated the significant enhancement in safety for passengers and crew members involved in a push mode collision with a standing locomotive train.

On December 3, 2003, a single-car impact test was conducted to assess the crashworthiness performance of a modified passenger rail car. A coach car retrofitted with a Crash Energy Management (CEM) end structure impacted a fixed barrier at approximately 35 mph. This speed is just beyond the capabilities of current equipment to protect the occupants.The test vehicle was instrumented with accelerometers, string potentiometers, and strain gages to measure the gross motions of the car body in three dimensions, the deformation of specific structural components, and the force/crush characteristic of the impacted end of the vehicle.The CEM crush zone is characterized by three structural components: a pushback coupler, a sliding sill (triggering the primary energy absorbers), and roof absorbers. These structural mechanisms guide the impact load and consequent crush through the end structure in a prescribed sequence.Pre-test activities included quasi-static and dynamic component testing, development of finite element and collision dynamics models and quasi-static strength tests of the end frame. These tests helped verify the predicted structural deformation of each component, estimate a force-crush curve for the crush zone, predict the gross motions of the car body, and determine instrumentation and test conditions for the impact test.During the test, the passenger car sustained approximately three feet of crush. In contrast to the test of the conventional passenger equipment, the crush imparted on the CEM vehicle did not intrude into the passenger compartment. However, as anticipated the car experienced higher accelerations than the conventional passenger car.Overall, the test results for the gross motions of the car are in close agreement. The measurements made from both tests show that the CEM design has improved crashworthiness performance over the conventional design. A two-car test will be performed to study the coupled interaction of CEM vehicles as well as the occupant environment. The train-to-train test results are expected to show that the crush is passed sequentially down the interfaces of the cars, consequently preserving occupant volume.

Three recent accidents involving the release of hazardous material have focused attention on the structural integrity of railroad tank cars:

Accidents that lead to rupture of tank cars carrying hazardous materials can cause serious public safety hazards and substantial economic losses. The desirability of improved tank car designs that are better equipped to keep the commodity contained during impacts is clear. This paper describes a framework for developing strategies to maintain the structural integrity of tank cars during accidents.