Crowd collapses and crushes

Crowd collapses and crowd crushes are catastrophic incidents that occur when a body of people becomes dangerously overcrowded. When numbers are up to about five people per square meter, the environment may feel cramped but manageable; when numbers reach between eight and ten people per square meter, individuals become pressed against each other and may be swept along against their will by the motion of the crowd. Under these conditions, the crowd may undergo a progressive collapse where the pressure pushes people off their feet, resulting in people being trampled or crushed by the weight of other people falling on top of them. At even higher densities, the pressure on each individual can cause them to be crushed or asphyxiated while still upright.

Such incidents are invariably the product of organizational failures, and most major crowd disasters could have been prevented by simple crowd management strategies. Such incidents can occur at large gatherings such as sporting, commercial, social, and religious events. The critical factor is crowd density rather than crowd size.

Crowd collapses and crushes are often reported incorrectly as human stampedes, which typically occur when a large group of people all try to get away from a perceived risk to life.

Background

One study has calculated that there were 232 deaths and over 65,000 injuries in the ten years between 1992 and 2002 as a result of such incidents, but crowd scientists believe that such casualties are both vastly under-reported and increasing in frequency. One estimate is that only one in ten crowd injuries occurring in doorbuster sales are reported, while many, if not most, injuries at rock concerts go unreported.