Common Misconceptions about Herd-type Behavior in Emergency Evacuations of Pedestrian Crowds

The authors critically scrutinize the existing body of theoretical and empirical evidence on the concept of “herd behavior” during emergency escapes of humans in crowds. The authors argue that many of the theories and assumptions borrowed from zoology or financial markets are not particularly transferrable to emergency evacuations context, and therefore could mislead the modeling. The authors discuss particular characteristics of this problem that makes it unique and different from the movement decisions of animal flocks or the decisions of financial agents. The arguments also suggest the inadequacy of the “followers/non-followers” dichotomy as an overly simplistic classification. People usually face conflicting information during emergencies between which they make ((possibly imperfect but) rational) trade-offs in order to make decisions. The influence of others’ actions is merely one contributing factor but not the entire picture and does not necessarily arise from the so-called “panic” state. Differentiating between various types of evacuees’ decisions, the authors also argue on the irrelevancy of the herd concept to the momentary (i.e. operational-level) decisions of pedestrians, reflected in the “attraction force” concept in some social-force-based applications. Moreover, the authors provide empirical evidence based on two datasets of hypothetical choices that strongly suggest the necessity (but not sufficiency) of certain levels of uncertainty in evacuation environment in order for herd-type behavior to occur. Overall, the work emphasizes on the necessity of studying this unique decision problem on its own merits based on dedicated experimentations rather than overgeneralizations from unrelated contexts, and that the assumption of imitative behavior in all situations of emergency escapes as a default seems to be overrated. In the conclusion, crowd evacuation is more complex than simple herding. The authors also enumerate a range of context-specific factors that may trigger or increase the possibility of displaying herding tendencies through which the authors suggest clear and specific directions for further research on this topic.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AHB45 Standing Committee on Traffic Flow Theory and Characteristics.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Haghani, Milad
  • Sarvi, Majid
  • Rajabifard, Abbas
• Conference:
  • Transportation Research Board 96th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2017-1-8 to 2017-1-12
• Date: 2017

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 21p
• Monograph Title: TRB 96th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Behavior; Crowds; Decision making; Evacuation; Pedestrians
• Subject Areas: Pedestrians and Bicyclists; Safety and Human Factors; Security and Emergencies;

Filing Info

• Accession Number: 01630052
• Record Type: Publication
• Report/Paper Numbers: 17-01822
• Files: TRIS, TRB, ATRI
• Created Date: Mar 27 2017 9:29AM