Firefighters’ behavior via vertical shafts in natural-ventilated tunnels

Abstract

Tunnel load traffic flows day and night, and is highly susceptible to catching tunnel fires. When a tunnel is on fire, occupants are endangered by the rapid deterioration of the tunnel environment during burning, and their self-evacuation is limited by their unfamiliarity with tunnels. Therefore, efficient and effective firefighting and rescue methods are urgently required to guarantee the safety of occupants during tunnel fires. During firefighting, one of the most important issues is that a fire brigade may encounter difficulties identifying the fire source. They have to deal with congestion and navigate cars piling into the tunnel, which wastes significant time. Therefore, this study provides an alternative approach for firefighters to access fire sources in naturally ventilated tunnels equipped with vertical shafts. This study explored three routes for firefighters from the ground to a fire source in a tunnel. The duration and speed of taking the three routes, along with the use of facilities, firefighters’ communication, and emotions, were presented and analyzed. This indicates that firefighting and rescue via vertical shafts is a feasible and optimized method for naturally ventilated tunnels because the estimated duration decreased by 56.2% (without smoke) and 60.0% (with smoke) compared to traditional routes when the minimum distance from the fire to the nearest exit is 2000 m. In addition, the study provides field experimental data on vertical firefighting in tunnels, which are expected to be used to build and calibrate models for firefighters in future studies.