An Accident Casual Model for Railway Based on Operational Scenario Cognition Conflict

Traditionally, accident or incident analysis are focusing on the cause-consequence chain methods, like Fault Tree or Event Tree, which are hard to find root cause of accidents. To solve this problem, some system safety analysis methods come out, like Accimap, FRAM and CAST based on STAMP. However, they are good at solving safety management issues, functional failure analysis or causal scenarios analysis, and can be used to capture safety requirements and help system designers to deep understand safety requirements. But the true logic of accident or incident do not analyzed, which is related to human or equipment cannot conceive the right status of train operational status on time. If so, it's easy to ensure safety by train stop. The objective of this paper is to present the mismatch or inconsistency among human cognition, equipment execution and train operation of railway train control system. Also, railway accident is a kind of expression of operational scenario conflict. Singapore metro accident is analyzed as case study.