Design of a Safety Protocol in Railway Signaling Systems

The railway signaling system is a safety related system composed of several sub-systems which have to exchange information with each other. As the communication system may be subjected to intentional or unintentional external attacks, the application of specific safety techniques is necessary. In this paper, a safety protocol is designed. Compared with the general TCP/IP protocol, a safety layer, on which several safety measures are applied to defense against the possible threats or attacks, is inserted between the top application layer and the lower transmission layer. The result illustrates that the designed protocol conforms to the international standard EN50129, and can switch the system to a fail-safe state when an unexpected failure or error occurs.