Statistical analysis and fire scale study of traffic tunnel fire accidents at home and abroad

To systematically characterize differences in the causes and consequence profiles of fire incidents among different types of transport tunnels, a database comprising 520 road-tunnel, 112 railway-tunnel, and 114 metro-tunnel fire incidents in China and other countries was compiled and statistically analyzed, and corresponding prevention and response measures were proposed. In addition, recommended design fire sizes for the three tunnel types were determined based on statistical data on transport-tunnel fires. The results showed that vehicle self-ignition was the leading cause of road-tunnel fires (64.4%), followed by rear-end collisions (23.5%). Rear-end collisions resulted in the largest total number of casualties, whereas arson and explosion incidents occurred infrequently but caused the highest average number of casualties per incident. Railway-tunnel fires were mainly caused by electrical failures (21.4%), mechanical failures (14.3%), train collisions (14.3%), and derailments or overturning accidents (17.0%), and their consequences were more severe than those of road-tunnel fires. Mechanical causes resulted in the largest number of fatalities (575 fatalities, averaging 35.9 per incident), whereas electrical failures resulted in the largest number of injuries (1,318 injuries, averaging 54.9 per incident). Metro-tunnel fires were mainly caused by electrical failures (43.9%), rear-end collisions (14.9%), and arson (18.4%). Among these causes, arson resulted in the most severe consequences, averaging 15 fatalities and 66 injuries per incident. Based on the statistical analysis, a design fire size of 30 MW is recommended for road tunnels, while design fire sizes of 20 MW and 15 MW are recommended for a single railway and metro carriage, respectively.