Hybrid causal methodology in quantitative risk assessment for the on-board ATP of high speed railway

This paper presents a quantitative risk assessment method based on the use of hybrid causal logic in the socio-technical system, the influence in the technological aspects is analyzed as well as in the operational aspects. Different modeling techniques and analyzing methods are applied in this paper aiming at different angles in the socio-technical system. Event tree and fault tree are used to identify the deterministic causal paths between components, the non-deterministic causal relationships (especially focusing on the impact of human factors and organization) are determined with Bayesian network (BN) (combining with evidence theory) and ω method. This paper has two objectives: One is that the hybrid causal framework for high-speed railway on-board automatic train protection (ATP) equipment is presented to assess risks quantitatively. The other is that the influence of non-deterministic factors (human factors and organization) in ATP equipment is analyzed combining with BNs, ω method and evidence theory.