An experimental study on the critical state of herd behavior in decision-making of the crowd evacuation

The research of crowd evacuation plays the predominant role of guaranteeing the controllability of the stampede disaster and decreasing accidents casualties. Herd behavior is one of the characteristic crowd evacuation behaviors, which has the definite influence on evacuees' decision-making and evacuation efficiency. In this paper, the crowd evacuation observation experiments were conducted to investigate herd behavior by considered 16 working conditions, including change the number of participants, alter urgency levels and set barrier. The participant allotment and crowd movement time on different sides and exits are obtained. The judgment area and crowd density are proposed to understand the herd behavior and choices of decision maker. The critical states of herd behavior in direction and exit choices are confirmed according to the video observation and data analysis. The results indicate that herd behavior moderately leads to the different distribution and movement time of the experimental crowd. Decision maker does not present herd behavior when crowd density is relatively high or low. When crowd density in direction choice judgment area is within the range of [1/12, 1/6] (person/m(2)), and the crowd density in exit choice judgment area is within the range of [1/27, 2/27] (person/m(2)), decision maker basically triggers herd behavior. This study provides insight into the critical state of herd behavior which deepens the understanding of crowd evacuation and contributes to the reference of the crowd accident management. (C) 2022 Elsevier B.V. All rights reserved.