On the Validation of an Interlocking System by Model-Checking

Railway interlocking systems still represent a challenge for formal verification by model checking: the high number of complex interlocking rules that guarantee the safe movements of independent trains in a large station makes the verification of such systems typically incur state space explosion problems. In this paper we describe a study aimed to define a verification process based on commercial modelling and verification tools, for industrially produced interlocking systems, that exploits an appropriate mix of environment abstraction, slicing and CEGAR-like techniques, driven by the low-level knowledge of the interlocking product under verification, in order to support the final validation phase of the implemented products.