Abstract
Railway signalling systems, which guarantee the safety of train operation, have been developed from the lessons learned from accidents. In the case of railways, the stoppage of trains is, in general, the safest when malfunction of relevant systems or any other difficulty happens, and this is a specific feature of railway signalling systems as well as the rationale for their fail-safe technologies. The safety of computerised railway signalling systems was realised by diagnostic functions and safety-fixed outputs on the basis of fail-safe concepts in 1980s. This paper discusses the safety technologies of railway signalling systems and their relation to functional safety, which applies to safety-related computer control systems.
