Model-Based Approaches for Railway Safety, Reliability and Security

In order to master the increasing complexity of modern railway control systems, novel model-based approaches are needed to allow engineers evaluate such systems against strict system-level dependability requirements. In this talk, driven by railway case-studies, we provide an overview of model-based approaches which have been succesfully adopted to ensure system safety, reliability and security. It is a matter of fact that dependability assurance requires holistic assessment both at the software and at the hardware levels. At the software level, models have proven useful to support both static and dynamic functional analyses in order to discover systematic faults in the code. At the hardware level, compositional multi-formalism modeling approaches well suited the evaluation of system safety and reliability against random faults. The use of models allows engineers to improve both the effectiveness and the efficiency of system verification. Views of the Unified Modeling Language can be adopted to perform informal or semi-formal analyses, while Stochastic Petri Nets, (Repairable) Fault Trees, Continuous Time Markov Chains and Bayesian Networks can be employed to perform formal and quantitative analyses. Furthermore, analytical risk and vulnerability models have also been experimented for security assessment with respect to intentional threats and natural hazards. Due to the wide range of possible applications, a promising research trend is devoted to the study of the challenging theoretical and technological issues related to the multi-paradigm dependability modeling using appropriate frameworks.