The Impacts Of Exit Conditions On Pedestrian Evacuation

Over the past few decades,lots of crowd accident happened all over the world.Door egress patterns have been considered as an important element in architecture design and crowd safety management under emergency situations.In some crowd gathering spaces like railway station,subway station,shopping mall,cinema and sports stadium,pedestrians usually move faster and push each other when evacuating from a chamber through an exit under emergency situations.These competitive collective crowd behaviors could potentially cause turbulence,resulting in crowd accident such as stampede.Such exit points are often considered as bottlenecks that impede the outflow of crowd.Therefore,in emergency cases,it is significant to enhance evacuation efficiency and safety when disasters happen in those public facilities.This paper studies crowd evacuation efficiency under different exit conditions by a series of experiments.Two variables were controlled in this series of experiments,i.e.exit position and obstacle placement.Fourteen experiments scenarios were established according to different exit position and obstacle.The entire process of this series of experiments was recorded by HD cameras.Then,trajectories were extracted by Tracker and transformed to physical coordinates.Based on the trajectories,both microscopic and macroscopic properties could be calculated.In this study,macroscopic properties of crowd movement behavior(i.e.density,flow and velocity)provided an insight on some phenomena and global outcome.Analysis of microscopic properties such as headway,instantaneous speed and conflict points can provide an insight on the possible causes for those crowd phenomena.Particularly,microscopic approach can take into account the local interactions to capture additional delays which are important during emergency situations.These local interactions finally lead to the global outcome or collective behavior which can be best studied with macroscopic properties.Based on these microscopic and macroscopic properties,different exit conditions were evaluate by two aspects,i.e.evacuation efficiency and safety.In this series of experiments,corner exits are better than middle exit.Placing a suitable obstacle in a correct position can improve evacuation efficiency and safety.Corner exit with suitable obstacle is the best one in this series of experiments.This study can provide rational suggestions for architecture and crowd safety management.The data obtained from these experiments are valuable resources to calibrate and validate the mathematical models intended to simulate the crowd egress behavior.