Our basic approach for crashworthiness assessment had three steps. The first step was to characterize the crash response of individual rail cars. For the North American train systems, we developed a detailed finite element model of a passenger car based on simplified assembly drawings. We characterized the crushing response of the car by simulating 30 and 60 mph collisions of the car with a 50 ton rigid but moveable mass. An example of the detailed model for a 60 mph collision with is shown in Figure 1. The response of the train car and the internal structural frame for this 60 mph collision are shown in Movie 1 and Movie 2 respectively. From these calculations we determined the collision response mechanisms for the train car and developed force-crush and force-energy curves.

The second step was to characterize train collision dynamics. We developed simpler finite element models of train cars that had crush characteristics similar to those calculated with the detailed model. We then calculated a range of train collision scenarios and determined the loss of occupied volume in crush zones and the acceleration histories in each of the train cars. These calculated acceleration histories for the train cars define the interior crash environments experienced by the passengers. An example of a very simple collision dynamics simulation for a three car consis impacting a 50 ton mass at 60 mph is shown in Movie 3. A similar simulation of the lateral buckling response for the derailment of freight train is shown in Movie 4.

The third step was to calculate the occupant response. We developed a finite element model of the occupant based on the structures and technology developed for anthropomorphic crash dummies used in automotive crash safety assessment. An interior model for the train car was developed from seat assembly drawings and force deflection measurements on the seat back. Occupant survivability was then assessed for secondary impacts resulting from the crash acceleration histories obtained from the collision dynamics calculations. A simulation of a 15 mph occupant secondary impact response is shown in Figure 2. An animation of the occupant secondary impact response is shown in Movie 5.

Figure 1 Train Car Crashworthiness Generic Passenger Car Impacting a 50 ton Mass at 60 mph.

Figure 2 Occupant Response Secondary Occupant Impact 15 mph Relative Velocity.

Movie 1 Train Car Crashworthiness: 60 mph into a 50 Ton Mass JPEG Quicktime Video (819 Kb)

Movie 2 Train Car Crashworthiness: Structural Frame Response JPEG Quicktime Video (936 Kb)

Movie 3 Train Set Crashworthiness: Simple 3-Car Train Model JPEG Quicktime Video (1.0 Mb)

Movie 4 Train Derailment Kinematics: Train Lateral Buckling JPEG Quicktime Video (1.1 Mb)

Movie 5 Train Occupant Safety: 15 mph Secondary Impact JPEG Quicktime Video (995 Kb)

J. W. Simons and S.W. Kirkpatrick, "High-Speed Rail Collision Safety: Crashworthiness and Accident Survivability,", Poulter Laboratory Technical Report 001-96, (June 1996)