Effects of obstacle number and layout on evacuation of high-density crowd at exits

Building exits are critical bottlenecks during evacuation. In this study, the effects of obstacle number and placement near exits on pedestrian flow are studied. Evacuation experiments are conducted, and obstacle number and layout, as well as competitiveness level, are considered in different scenarios. Pedestrian trajectory data along with pressure measurements at the exit are analyzed to assess evacuation efficiency, collective movement patterns, and force distribution. The results indicate that the impact of obstacles depends on their number, placement, and the level of competitiveness. Under high-competition conditions, appropriately placed obstacles increase evacuation efficiency by up to 29.6 %, reduce collective lateral rushes by 49.9 %, and improve the global alignment parameter by 26 %. Pressure measurements further indicate that the forces exerted on the exit wall are reduced when obstacles are used at an appropriate position. Based on experimental and theoretical analysis, the mechanisms by which obstacles influence evacuation dynamics are elucidated. The study may provide empirical evidence for understanding crowd behavior and offer practical guidance for crowd management in high-density environments.