A catastrophic high-speed train crash caused by a small-scale debris flow in China

Abstract

On June 4, 2022, a D-series high-speed train was struck by a small-scale debris flow composed of landfill-based source materials in Guizhou, China. The accident caused two railway carriages to derail, killing the driver, and injuring 12 people; the remaining 132 passengers were evacuated. Based on the investigation, the debris flow was related to uncompacted waste soil produced during expressway construction above the railway. On the day of the accident, the region experienced a short period of heavy rainfall, which led to soil saturation and shear strength reduction. The unstable landfill provided the source materials for the debris flow. Impact analysis between moving trains and hazards such as debris flows is a useful tool to mitigate the propagation of adverse consequences. Few studies quantify the train impact probability from a real-time evaluation perspective. The effect of the application of an early warning system on the impact results has also been rarely studied. To better understand the debris flow event, and provide corresponding suggestions for improving the warning system based on the proposed impact probability, this study explored the basic characteristics of the debris flow based on multisource information and analyzed the initiation mechanisms: landsliding. A quantitative method considering timetable information for assessing the real-time impact probability between a moving train and runout materials along the track was developed. Analysis of the implementation of an early warning system showed that the impact probability between a moving train and on-track deposited materials was reduced given a shorter warning interval. A warning interval of 46 s and a working time between 8:00 and 20:00 could be reasonably suggested for early warning system applications in this case. The developed approach and relevant suggestions could facilitate the improvement in future early warning systems along railway lines.