The FTA based safety analysis method for urban transit signal system

As an effective means of solution to traffic congestion, the modern urban transit has attracted worldwide attention. The signal control system, the core parts of the urban transit, is a typical safety critical system which ensures the safe operation and improves the transport efficiency. Therefore, the safety of the system must be analyzed during the development, production, and evaluation processes. Due to the system itself, operating environment, staff operation and other factors, the different failure modes which impact the system reliability and safety will occur during operating of the signal system. According to the system functionalities and system structures, the failure reasons can be analyzed layer by layer to improve the system design and performance. This paper suggests a safety analyze method for the signal system on the basis of the technical features using fault tree methods, and gives the proposals to improve system design.