Application of UML sequence diagram in CTCS-3 onboard system hazard identification

With the development of Chinese high-speed railway system, the safety of CTCS-3 system is drawing more and more attention. Hazop is a useful method to conduct hazard identification for the CTCS-3 system. In this paper, a complete process of identify the potential hazard of CTCS-3 onboard system on the basis of UML sequence diagram is shown, which can find out the hazards through analysis of every information and behavior interaction between different components of the system by the experts on the hazop conference. So, the sequence diagram is kind of the most directly model to provide basis for the hazard identification. Possible severity estimation and actions to avoid the hazards should also be proposed on the conference.