To simulate pedestrian evacuation processes on a metro station platform in a case of fire, a specific evacuation model is proposed, using an integrated cellular automata (CA) approach, in which the impacts from exits, other evacuees, and fire and smoke are included to measure the probability of the evacuee getting to each neighboring cell. The evacuation is firstly identified as a two-stage process including the motion on the platform and on the treads. Then the evacuation space is drawn to be a three-dimensional grid space, in which the cell size is defined by the stair structure and human body size. Based on that, this study proposes two CA models to simulate the evacuees’ movement and the smoke diffusion separately. Moreover, to describe the evacuation process in detail, the evacuation model is modified in three ways. First, transition rules in the evacuees’ movement model are embedded by social force theory to measure the impacts from the environment. Second, the smoke diffusion process is modified by considering the smoke control measures on the metro platform. Third, impact from smoke is quantified by the proportion of smoke in the centroid cell of evacuees. Finally, results from simulation experiments show that this model is able to recognize the arching and stagnation phenomenon at the foot of staircases, and the relations between the evacuation time and the crowd density for different parameters are also analyzed. The proposed method of simulating the pedestrian evacuation process can be useful in providing guiding principles for the software design of evacuation in metro systems.
Three-Dimensional Evacuation Model with Applicability Based on the Theory of Cellular Automata
