198911 – McDonald – “Westrace”: Second Generation Solid State Signalling

This paper traces the development of a modular Solid State Signalling System specifically developed for the Railway Industry. The movement from relays to electronic equivalents is reviewed as a basis for expounding some fundamental design principles. A short analysis of the role of safety is presented.

WESTRACE Vital Signalling Systems are overviewed in terms of equipment design and the application to typical railways. Finally, the paper considers the future potential for fail-safe electronics in the railway environment.