Design and implementation of a safety-critical domain specific language for on-board train control

A safety-critical domain-specific language is presented, EXS (ETCS eXecutable Specification). The language is designed to facilitate the implementation of on-board signalling applications responsible for the safe movement of trains, more specifically according to the European Train Control System (ETCS). The implementation of this language on a safety critical platform is presented, and is illustrated with various examples of applications developed, tested, and deployed on a fleet of freight locomotives running on the Belgium network. Lessons learned are presented, and future possible developments are discussed.