201811 – Shead – Safety and Reliability in Signalling Systems

Major projects today request high performance criteria for Reliability, Availability, Maintainability and Safety of Signalling Systems often referring to be compliant with Standard EN 50126/9. Considering that, it would be an extensive task to condense the standard into this paper, which will concentrate on the Safety aspects and the Reliability of Signalling systems. Safety in itself we can expand in a number of ways take for instance the title of RAMS, this is frequently extended to RAMSS, which includes the aspect of Security and these security features will be discussed. Reliability on the other hand goes hand in hand with Availability but namely addresses the issue of probability.