The major functionality of railway traffic control system is to ensure efficient and safe railway traffic. Contemporary technique, electronics and informatics in particular, allows for automation of more and more tasks in transportation processes. Irrespective of the manufacturing technology, railway traffic control systems have to meet specific safety requirements. Because of this, these systems belong to group of safety-critical systems, also called safety-related systems. Due to these requirements, development, building and verification processes of railway traffic control systems always end with the assessment of correctness of each process. It should be pointed out that these processes are compound and require high skills level for persons involved in it. Because of this, an environment for an expert system (ExSys Corvid) can be used to automation of these processes. Authors used ExSys Corvid environment to build the expert system for verification and validation of Level Crossing Protection System (LCPS). Research conducted by authors confirmed high usefulness of this technology and showed the need for the usage of it in other railway traffic control systems.