Abstract: In order to explore formation mechanism of emergencies along line caused by external environment of high-speed rail, and all risk factors that cause emergencies along line was studied, based on Tropos risk framework, a social technology system model for emergencies along high-speed rail was constructed. Apply risk analysis theory, risk points through mining of actors was identified, and formation mechanism of emergencies along high-speed rail was analysed.List of potential safety hazards along high-speed rail was extracted, and practical and feasible prevention and control measures were put forward. The research results show that sources of emergencies along high-speed rail line mainly include natural environment, people, construction units, surrounding objects and animals, illegal behavior of pedestrians on the road and other risk factors such as illegal construction by construction unit are important sources of emergencies along high-speed rail. In addition to natural environment and surrounding objects that directly affect safety of high-speed rail operations, and there is coupling effect between the two on high-speed railway.

Key words: along high-speed rail line, external environment, Tropos risk framework, social technology system model, risk identification