Dynamics of crowd disasters: An empirical study

Many observations in the dynamics of pedestrian crowds, including variousself-organization phenomena, have been successfully described by simplemany-particle models. For ethical reasons, however, there is a serious lack ofexperimental data regarding crowd panic. Therefore, we have analyzed videorecordings of the crowd disaster in Mina/Makkah during the Hajj in 1426H onJanuary 12, 2006. They reveal two subsequent, sudden transitions from laminarto stop-and-go and ``turbulent'' flows, which question many previous simulationmodels. While the transition from laminar to stop-and-go flows supports arecent model of bottleneck flows [D. Helbing et al., Phys. Rev. Lett. 97,168001 (2006)], the subsequent transition to turbulent flow is not yet wellunderstood. It is responsible for sudden eruptions of pressure releasecomparable to earthquakes, which cause sudden displacements and the falling andtrampling of people. The insights of this study into the reasons for criticalcrowd conditions are important for the organization of safer mass events. Inparticularly, they allow one to understand where and when crowd accidents tendto occur. They have also led to organizational changes, which have ensured asafe Hajj in 1427H