Insulated rail joint enhancement: testing and analysis

Joints in railway track are vulnerable to failure, so most modern rail is welded. However, many signalling systems rely on sections of rail being electrically isolated from adjacent sections so insulated joints are necessary. At these joints several millimetres of insulation material, an “end post”, separates the ends of the rails. To support the rail two pieces of steel (known as fish-plates) are bolted on either side of the rail web. All steel components are separated from each other by insulation material. Conventional designs of rail joints are known to suffer from a range of failure modes: bolt failures, rail breaks, fish-plate failure, insulation degradation, and lipping (in which plastic flow in the rail ends bridges the gap between the rail ends). To assist in developing improved designs accelerated test procedures and sophisticated finite element models have been developed; this paper describes both. Results from physical testing and numerical modelling are presented and compared.