Full-scale experimental study and formular movement modelling for firefighting routes via vertical shafts in natural-ventilated tunnels

When a tunnel is in fire, occupants could be trapped in a dangerous environment due to the rapid deterioration of fire development, and their self-evacuation suffers huge challenges on account of their unfamiliarity to tunnels. Hence, efficient and effective firefighting and rescue are in urgent needs. During firefighting, one of the spiniest issues is that the fire brigade may meet trouble to arrive at the fire source. They have to deal with the congestion condition and pass through those cars piling in the tunnel, which wastes huge time. Aiming at this, the present study provided an alternative approach for the firefighters to get access to the fire source for those natural-ventilated tunnels equipped with vertical shafts. The study explored three firefighting routes from the ground to the fire source in the tunnel for firefighters. The time and speed of the three routes along with the use of facilities, firefighters’ communication and feeling are presented and analyzed respectively. It indicates that firefighting and rescue via vertical shafts could be applied as a feasible and optimized way for natural-ventilated tunnels. Moreover, five formulars of firefighting movement are proposed and compared, and the logistic model performed the best. According to the logistic movement model, the estimated time showed a decrease of 56.2 % (without smoke) and 59.8 % (with smoke) compared to traditional routes when the minimum distance from the fire to the nearest exit is 2000 m. The study provides field experimental data on vertical firefighting in tunnels and those data are expected to build and calibrate refined models for firefighters in the future study.