Microscopic events under high-density condition in uni-directional pedestrian flow experiment

In order to investigate the pedestrian behaviors under high-density condition, we organize one experiment with 278 pedestrians, and the global density as high as 9 ped/(m̂2) is reached. The experiment is filmed by one unmanned aerial vehicle (UAV). In the experimental video, we find many interesting microscopic events. They can be categorized into two types: the interactions with the boundaries (Type A) and the absentmindedness (Type B). Among them, ”the staffs arrange the stools” (Event A1) and ”the pedestrians play with mobile phones” (Event B1) can be measured and evaluated. We find the time series data of Event A1 and B1 have strong relationship with the evolution of pedestrian flow. The results in hyper-congested state and that in over-congested state are qualitatively different, and the critical density is about 8 ped/(m̂2). At the same time, the averaged results of both Event A1 and B1 qualitatively change at about 6 ped/(m̂2), which is the critical density between over-congested state and congested state. Why different pedestrian flow data have different maximum densities also can be explained by this critical value. Therefore, the bridge between pedestrian dynamics and individual pedestrian's behaviors is built in this study.