Uml-based Design and Formal Analysis of a Safety- Critical Railway Control Software Module

A new equipment of safety relevance has been developed to upgrade ageing relay-based railway interlocking systems in Hungary. In course of the design process formal methods have been used in the development of a module realising a well-separable function of the system. Namely, the UML-based design process was extended by model based analysis and validation. The first kind of analysis checked the completeness and consistency of the behavioural description of the module. In the subsequent phases, the functional design was enriched by modelling the potential faults and their effects. This kind of extension allowed the analysis of the error propagation and testability.