Effect of Passenger Physical Characteristics in the Uptake of Combustion Products during a Railway Tunnel Evacuation Due to a Fire Accident

The current study examines how different types of passengers (elders, travelers with luggage, travelers without luggage, and mixed population) affect the evacuation process in railway tunnels after a fire accident based on Fractional Effective Dose (FED) index values. A 20 MW diesel pool fire in an immobilized train located inside a straight, rectangular railroad tunnel that is ventilated by a longitudinal jet fan ventilation system is the scenario under consideration. Two fire scenarios were examined, one with and one without ventilation, combined with four evacuation scenarios. The numerical simulation of the fire and the evacuation process is conducted with the Fire Dynamics Simulator and Evacuation code (FDS + Evac) which is a Large Eddy Simulator (LES) for low-Mach thermally driven flows. The results (evacuation times, walking speeds, and mean and max FED values) are compared for each passenger type. It is found that during the evacuation from a railway tunnel fire accident, the most affected population are the elderly because of their lower movement speed, and travelers with luggage because of their increased dimensions. It is also shown that a non-homogenous population has increased uptake of combustion products and longer evacuation times than a homogenous population with similar geometrical characteristics.

Automated summary

This study investigates the impact of different passenger types (elders, travelers with luggage, travelers without luggage, and mixed population) on the evacuation process in railway tunnels after a fire accident using Fractional Effective Dose (FED) index values. The scenario considered is a 20 MW diesel pool fire inside a straight, rectangular railroad tunnel with a longitudinal jet fan ventilation system. Two fire scenarios (with and without ventilation) and four evacuation scenarios were examined. Numerical simulations of the fire and evacuation process were conducted using the Fire Dynamics Simulator and Evacuation code (FDS + Evac), a Large Eddy Simulator (LES) for low-Mach thermally driven flows. The results (evacuation times, walking speeds, and mean and max FED values) were compared for each passenger type. It was found that the elderly are the most affected during evacuation from a railway tunnel fire accident due to their slower movement speed, and travelers with luggage are also significantly affected due to their increased dimensions. Additionally, a non-homogenous population experiences higher uptake of combustion products and longer evacuation times compared to a homogenous population with similar geometrical characteristics.