Reliability evaluation of the Chinese Train Control System Level 3 using a fuzzy approach

The Chinese Train Control System Level 3 (CTCS-3) has been developed to ensure the safe and efficient operation of high-speed railway networks in China. Failure of the CTCS-3 may result in serious accidents, causing damage to assets and risking the safety of passengers. In this paper, the reliability evaluation of the CTCS-3, comprising an onboard and trackside subsystem, is conducted using the fault tree analysis where the basic events are divided into known failure rate basic events and unknown failure rate basic events. The probabilities of the occurrence of the known basic events are obtained from field data, while those of the unknown failure rate basic events are estimated by expert judgment. The fuzzy set theory is then adopted to deal with the imprecise expert judgment. Considering a specific operational scenario, to accomplish one mission, the failure probability of the CTCS-3 is calculated. Importance analysis is carried out not only to identify the critical basic events but also to provide suggestions on the improvement of preventive maintenance. Sensitivity analysis shows that hardware factors have the most significant effect on the reliability of the CTCS-3