A modified cellular automaton model of pedestrian evacuation in a tunnel fire

Abstract

This paper presents evacuation simulations of occupants’ flow in a tunnel fire via a modified cellular automaton model and puts forward corresponding optimized evacuation strategies. A 2-D grid field represents the simulated tunnel and a 20 MW fire is placed in the middle of the tunnel. Fire, as the key factor is regarded both as a dynamic obstacle along with its development and a repelling force on each occupant. During occupants’ movement, game theory is taken into consideration when people intend to move to the same target simultaneously and they could either corporate or fight for the target. Seven exits layouts and the moving conflict preference of pedestrians during movement are investigated with three levels of crowd densities namely low, medium and high in conditions either with fire or without fire. The results show frequent conflict among occupants and single, overlaid exits will result in a longer evacuation and a declined evacuation efficiency. The decline is very sensitive to crowds’ density and the high crowd density performs a much worse evacuation efficiency. In addition, the fire aggravates the decline to a large extent in all conditions and it would lead to a larger possibility of injury for occupants during evacuation in a tunnel fire. Therefore, it is necessary to predict evacuation flow prudently with models considering fire rather than those without fire, which may result in an unrealistic optimistic result.