A study on the arch mechanism of pedestrian evacuation and congestion alleviation strategies at building exits

The pedestrian flow capacity of building exits has always been a focus of research in evacuation field. This paper focuses on the congestion mechanism of pedestrian flow at exit bottlenecks through simulation and crowd experiments, and tries to propose strategies to alleviate evacuation congestion. Firstly, pedestrian flow evacuation experiments were conducted by setting up scenarios with exits in the middle and corners, and corresponding exit structure models were established using Massmotion software to analyze the congestion mechanisms of pedestrian flow at the exits through simulations coupled with the social force model. Secondly, the severity of congestion in the exit structure was quantified using the example of the middle exit. The width range of the pedestrian evacuation trajectory within 1 m before the exit was defined as the average chord length of the arch structure, and the area enclosed by the semicircular arch with this chord length was defined as the area with a relatively high instantaneous density of pedestrian flow. The results indicate that corner exits are more conducive to evacuation as they reduce the expected velocity of pedestrians near the center of congested areas. Both building width and the inflow rate of pedestrian flow, along with the number of pedestrians, demonstrate significant effects on the average chord length of the arch. The research results can be used to further supplement and improve the dynamic theory of pedestrian flow evacuation in buildings and provide a scientific reference for crowd congestion control at building exits.