Experimental study of the influence of proactive avoidance and emergency degree on bidirectional pedestrian flow

With the increase in emergency incidents, research on pedestrian dynamics has received widespread attention. Bidirectional pedestrian flow has been identified as a major factor in numerous global disasters over the past few decades. Conflicts can arise between individuals moving in opposite directions. Additionally, under different emergency conditions, evacuation behavior can vary significantly. This study primarily examines the impact of proactive avoidance and urgency on bidirectional pedestrian flow.

Experiments were conducted by establishing an outdoor experimental setup and recruiting participants. A controlled variable method was used to design 17 experimental trials to investigate the movement of bidirectional pedestrian flow under different levels of urgency and the presence of proactive avoidance behavior. Variations in urgency and proactive avoidance were implemented through a monetary reward and penalty mechanism. Pixel coordinates were first recorded using the Tracker software and then converted into real-world coordinates using direct linear transformation. The analysis focused on the evacuation speed, evacuation time, movement trajectories of the evacuees, maximum offset during the evacuation process, and behavior exhibited throughout the evacuation. Moreover, variance analysis was conducted to assess the stability of the experimental conditions and the validity of the experiments. Finally, a questionnaire was administered to collect some basic parameters of the participants, such as height, weight, and age. Furthermore, information on whether the participants experienced feelings of anxiety during the experiment and their perspectives on whether the provision of additional rewards influenced their sense of urgency was obtained.

Common phenomena observed during the evacuation process included overtaking, following, and side-by-side behavior. An innovative behavior termed boundary flow acceleration was identified, where individuals moving against the flow exhibited significantly higher walking speeds when adhering to the wall compared with those not using the wall for support. Notably, groups of individuals moving against the flow spontaneously formed lanes when faced with a larger number of pedestrians moving in the opposite direction, which enhanced their ability to navigate through the crowd. In emergencies, the evacuation speed of individuals with disabilities was slower than that of normal pedestrians. Therefore, individuals with disabilities need more attention during emergencies. In nonemergency situations, the average evacuation speed of individuals moving against the flow was 1.26 m/s, which increased to 1.49 m/s when proactive avoidance behavior was present. In emergencies, the average speed of individuals moving against the flow increased to 2.04 m/s. When no individuals were moving against the flow, the evacuation speed was 1.77 m/s in nonemergency situations and 3.50 m/s in emergencies. The questionnaire results indicated that approximately 82.9% of the participants experienced anxiety during the evacuation process, and 91.4% of the participants believed that providing additional rewards could enhance the urgency of the experiment. This finding validated the effectiveness of the monetary reward mechanism in simulating emergency conditions.

The results indicated that proactive avoidance behavior effectively reduced pedestrian conflicts. Moreover, the behavior improved the evacuation efficiency of individuals moving against the flow by 24.60% and increased the evacuation speed by 19.87%. Furthermore, the phenomenon of stratification became more pronounced with the introduction of proactive avoidance behavior. Compared with nonemergency situations, the evacuation speed of the larger crowd significantly increased compared with that of the smaller crowd during emergencies. These findings can provide valuable insights for managing bidirectional pedestrian flow in emergencies and offer relevant support for modeling research in this area.