Reliability methodology and theory for development of novel railway signalling systems

Driven by the high maintenance and repair cost, low operation efficiency and unsatisfactory safety level of the current railway systems, the autonomous perception and radio-based railway signalling systems are attracting world's attention. In development of these systems, a severe challenge is guaranteeing the software reliability. In this paper, a novel approach is proposed to analyze and formalize the requirements specification, which is the basis of software system. Specifically, firstly, in order to improve the accuracy of the translation from an original specification into a formal specification, dynamic state translation diagrams are extracted to express internal operation mechanisms and state changes. Followed by graphical UML models are created for a comprehensive and object-oriented analysis of the system structure. Thirdly, rigorous and explicit formal specification is established using VDM++. Lastly, system properties are validated by discharging the proof obligations of the formal specification. The satisfiability is validated by simulation and systematic testing.