Techniques for improving the crashworthiness of existing designs of railway rolling stock

Abstract

The United Kingdom railways operate passenger carrying rolling stock of a great many different designs and ages. One type, designated as the Mark 1, was designed and built in the early 1950s with production continuing well into the 1970s. This vehicle's basic design consists of a substantial underframe to which is attached, at either end, two four-wheel bogie sets. A relatively light body is then attached to this underframe. Since these vehicles were introduced in the UK, a number of serious overriding collisions have taken place. In the case of the Mark 1 vehicle an override occurs on impact when the underframe of one vehicle climbs over the other vehicle. The overriding underframe then continues to penetrate the vehicle's upper body with potentially serious consequences. The UK Railway Inspectorate fimded a series of research programmes to investigate the feasibility of carrying out inexpensive in-service modifications to improve crashworthiness. The research involved using dynamic FE modelling, laboratory testing and full scale crash tests to develop three concepts. These were a shear out coupler, a method for locking the underframe ends together in a crash, and a modification to the underframe to initiate energy absorbing folding.