SIGNAL+DRAHT | Issue 12/2003
The Relationship between the CENELEC Railway Signalling Standards and Other Safety Standards
Although there are many different international, European, Japanese and US safety standards, these standards coincide in many general aspects and concepts. However, there are several differences in detail, e.g. while the TFM, THR and MTTHE concepts are very similar with respect to setting safety targets, the verification process for assuring that the targets are met, differs. The most important differences are:
- The SIL concept is not common in the US railway industry.
- Rather than using quantitative analyses and absolute targets, in Japan qualitative analyses including hazard analysis are emphasised for safety evaluation, and quantitative analyses perform a confirming role.
- The attitude to and application of standards. They are sometimes treated as guidelines and sometimes as mandatory regulations.
- Terminology