Faster and safer evacuations induced by closed vestibules

Abstract

In this paper, we use the social force model, to optimize high-anxiety pedestrian evacuations. We explore two architectural layouts, the 1-door vestibule, and the 2-doors vestibule. The “vestibule” is defined as the room next to the exit door and it is characterized by two structural parameters: the vestibule width (d) and the vestibule door width (w). Specific values of d and w, can almost double the evacuation flow compared to the no-vestibule scenario. The key to this achievement is that the density (close to the exit door) can be controlled by d and w. Therefore, it is possible to tune these parameters to a density that maximizes the available space while preventing the formation of blocking clusters at the exit door (rho~2.5 p/m^2). As opposed to the optimal condition, low-density values (rho~ 1p/m^2) lead to suboptimal flow since there is unused space left; while higher density values (rho~4p/m^2) also lead to suboptimal flow due to the presence of blocking clusters. Moreover, we take into account the fact that high pressures can actually be reached at the exit, threatening the health of pedestrians. We studied the crowd pressure using the agents’ overlap as an indicative. The explored vestibules reduce the crowd pressure compared to the no-vestibule situation. In particular, we show that the 2-doors vestibule scenario performs better than the 1-door vestibule, because it reduces the overall local density (by enforcing the crowd to spread out more).