Research On Vulnerability Of Urban Rail Transit Signaling System Based On Petri Net

Signaling system, as a central system to make sure the safe organization of rail trains, directly affects the many aspects including service level, transport efficiency and so on. With the intensive study on signaling system, the research method of urban rail traffic signaling system has been relatively mature. However, the most current studies focus on the assessment of risks, analysis of reliability and configuration in signaling system. Few scholars conduct research on vulnerability analysis and its evaluation in urban rail transit signaling system. Vulnerability is the intrinsic properties of a certain system, which is a fundamental reason resulting in faults or accidents. Vulnerability studies of signaling system will help urban railway enterprise know the accidents and malfunctions allsidedly from the view of essential safety. Vulnerability can solve practical problems from the perspective of intrinsic safety for promoting enterprise prevent and aware of accidents and malfunctions more comprehensively and deeply.Petri net, as a method of modeling and analysis signaling systems, has become one of the main modeling tool to study the signaling system because of its intuitive expression and rigorous mathematical logic. Therefore, the paper used objects oriented colored petri net to model urban rail transit signaling system and analyz its vulnerability, which was the foundation to propose a method of quantifying vulnerability.Firstly, the concept of vulnerability of signaling system was defined, according to the geographical distribution of the signaling system. Function model was selected to study the vulnerability of signaling system after compareing different evaluation methods. The main vulnerability factors of signaling system were identified using failure analysis technique.Secondly, the paper divided signaling system into four subsystems that Line Trackside subsystem, Train subsystem, Control Center subsystem and Train Depot subsystem based on the actual management mode and established Objects-oriented Colored Petri net of signaling system on the basis of Communication Based Train Control System as well as its data transmission. Moreover, we proposed calculation steps and route search algorithms of signaling system’s vulnerability according to the dynamic characteristics of Petri nets and the definition of vulnerability of signaling system.Finally, we calculated and analyzed the result of vulnerabilities of Line Trackside and Train subsystems in an example instance, which will contribute to management and design through quantitative analysis of vulnerability of urban rail transit signaling system with the result that a strong correlation exists between faults and vulnerability, have been reached the purpose of quantifying signaling systems’vulnerabilities.