Identification of causal scenarios and application of leading indicators in the interconnection mode of urban rail transit based on STPA

Abstract

Pre-accident prevention is an important measure to ensure the safety of urban rail transit operation. The operation scenario of urban rail transit system is complicated, which requires the hybrid control of human (driver) and machine (train control system). In the interconnection mode, cross-line operation between two subway lines involves control interaction of different lines. The System-Theoretic Process Analysis (STPA) method searches the cause of the accident based on the extended accident causal model. It decomposes the causes of the accident into causal scenarios and proposes safety constraints. Based on casual scenarios and safety constraints, together with the safety assumptions of train operation, the leading indicators can be proposed. With Chongqing Metro Line 10 and the Loop line as an example, we analyzed the casual scenarios of the cross-line shunting process in the interconnected mode, and proposed leading indicators. The results can effectively observe and prevent risks. The indicators identified by the method in this paper can meet the requirements of “full period, all space and the whole process” of the operation unit, and makes up for the problem that the existing indicators cannot clearly indicate the risks.