Connection between reliability and signalling-safety in railway technology

It is shown that signalling safety is a subterm of reliability. This connection is not generally known, although railway signalling engineers have been pioneers in this field. It is pointed out that the main tools for implementation of signalling safety are fail-safe techniques, and it can be shown that most of the methods used for fail-safe validations are the same as these in reliability techniques. All systems or equipment must be validated and certified regarding correct fail-safe behavior. As an important condition for the validation work, clear terminology is urged by the author because of comparability of the certificates