Modelling System Reliability Aspects of ERTMS/ETCS by Fault Trees and Bayesian Networks

ERTMS/ETCS is a recent standard specification aimed at improving interoperability, performances and dependability of modern railways. An implementation of ERTMS/ETCS is a distributed heterogeneous system with strict availability requirements. On the basis of such requirements and of the hypothesised system reference architecture, we studied structural availability by instantiating models with realistic reliability parameters and performing a series of sensitivity analyses in order to highlight design trade-offs. By evaluating and integrating sub-models using a compositional approach we both obtained several interesting results and showed the effectiveness of a combined use of Fault Trees and Bayesian Networks in dealing with structural reliability analyses of train control systems.