Influence of the Slope and Delay on Passenger Evacuation from a Fire Along a Railway Tunnel with Natural Ventilation

Passenger safety is one of the main goals of railway tunnels design, being the evacuation of a burning train one of the worst scenarios, where any delay to start the evacuation is crucial for passenger's survival. Previous research works have separately studied the evacuation of railway tunnels due to fires and the effect of tunnel slope on gas and smoke spread, but none of them has addressed both factors together. In this work, we developed a quantitative approach to assess the time delay to start the evacuation, depending on the tunnel slope. The methodology is based on statistical analysis of simulation results. The proposed model, based on linear multiple regression with an R-square value close to 90%, explains the number of fatalities as a function of the time delay to start the evacuation and the tunnel slope. The statistical model used in this study predicts more than one fatality for each second of delay in starting the evacuation. Moreover, tenable conditions for safe evacuation in case of fire cannot be easily guaranteed in inclined tunnels with more than 1 km length and natural ventilation.