A real-time model of railway interlocking system based on UML extension mechanism

Railway interlocking system (RIS), a very important part of the railway signaling system (RSS), greatly achieves the intelligent control of the train route process, and improves the efficiency and reliability of the route management Modeling with UML contributes to the connection between rail experts and related system developers. However, the standard UML can´t meet real-time requirements of RIS which is typically safety-critical, due to its lack of precise definitions of time. Therefore, a complete and reliable modeling method with time constraints to RIS becomes urgent. The UML extension mechanism based modeling method with time constraints (UemBMMwtc) is introduced in this paper to model the terminals in decentralized railway interlocking system (DRIS) by statecharts, by which to conquers the lack of the time factor in standard UML and greatly improves the credibility and usability of DRIS.