Practical Experience Report: Implementation, verification and validation of a safe and secure communication protocol for the railway domain

Different communication protocols are currently being used for the railway domain. However, most of these protocols rely on many interlacing mechanisms and safety codes which raise their complexity. Therefore, companies operating in the railway domain, guided by the Italian railway network manager, devised the Protocollo Vitale Standard, a light network protocol that stems from the Euroradio and RBC-RBC (Radio Block Centre) protocols. In this paper we report our practical experience in the implementation of the Protocollo Vitale Standard in compliance with a CENELEC SIL4 safety target. The implementation of this protocol required assembling a V&V&S plan to specify all the V&V activities that need to be carried out before, during and after the implementation of the protocol. Moreover, coding styles, standards and code quality metrics are defined, and cross-checked at various stages of the implementation. To complete our work, we conducted tests and performance analyses on the source code, while currently we are devising an adequate safety case aiming at a future certification.