The railway interlocking system (RIS) is one of the crucial parts of the railway transit safety. In the French railway domain, the computer-controlled relay-based interlocking systems are the dominant practice. Their complex sequences and consequent actions make it difficult to formally validate their safety properties. For such a system, detailed verification and validation of its specifications should be done at the end of the design phase. In practice, each station or yard in a railway line has its own interlocking system, which respects the same national standard but has a different facility formation. In order to effectively accomplish the validation tasks and reduce the error probability, this paper introduces a modelling pattern of the French railway interlocking system, which is a parameterized model respects the French national rules. It is a general reusable solution to this kind of problem and can be used in many different given contexts.