The development of safety cases for mass transit signalling and control projects-Jubilee Line case study

This paper outlines the strategy adopted by Westinghouse Signals Ltd., for producing the System Safety Case submissions required to support the Jubilee Line Signalling System. The format and structure of the Safety Case interfaces directly with the railway system level documents produced by the Client in support of the Safety Case for Transport Systems required by legislation. The strategy for implementing the System Safety Case is based on National and International Standards, e.g. CENELEC ENV 50129, IEC 1508. In order to implement this strategy, the Westinghouse Signals Ltd. Jubilee Line System Assurance Team is separate from the Design Team. This ensures that the system design does not become 'unmanageable' in terms of successful completion of the Safety Case, and also enables provision of guidance to be given to the management, design and implementation in order to achieve a demonstrably safe, reliable and maintainable system.