Fuzzy fault tree analysis of railway traffic safety

The safety analysis of railway traffic system is presented in this paper. Fuzzy fault tree technique has been adopted in safety analysis. The main traffic accidents-top events of fault trees-have been analyzed down to the level of human errors and hardware failures. In the fuzzy fault-tree model, the possibility of failure, i.e. a fuzzy set defined in probability space, is proposed to replace the probability of failures. The maximum possibility of railway traffic system failure is determined from the possibility of failure of each unit within the system according to the extension principle. An example is given to illustrate the method.