A Kind of Fail-Operational Realization Method Based on Active STPA

With the development of train control systems towards autonomous and unmanned direction, drivers no longer control trains. But safety and efficiency have always been a key concern of the railway industry. To balance safety and efficiency, the concept of “fail-operational” has been proposed. From the perspective of whether the train itself can continue to operate, based on the advantages of STPA method in risk identification, Active STPA is proposed to analyze and judge the “fail-operational” of the train. This paper selects a case of emergency braking failure caused by secondary slipping during the entry process of the Yanfang Line, and uses the Active STPA method for safety analysis. The results indicate that relevant constraints SC need to be supplemented: In the event of a malfunction, the interaction between the dispatch center and the site should be strengthened. Meanwhile, during the data collection process, through communication with on-site experts, it was indicated that during the current operation of the Yanfang Line, small-scale slip faults do not lead to direct emergency braking, presenting a “fail-operational” trend. It demonstrates the completeness as well as the depth of the active STPA approach to analysing accident cases.