From Fruin "Cause and Preventions of Crowd Disasters"
Compressive asphyxia has occurred from people being stacked up vertically, one on top of the other, or horizontal pushing and leaning forces. In the Ibrox Park soccer stadium incident, police reported that the pile of bodies was 3 m (10 feet) high. At this height, people on the bottom would experience chest pressures of 3600-4000 N (800-900 lbs.), assuming half the weight of those above was concentrated in the upper body area.
Horizontal forces sufficient to cause compressive asphyxia would be more dynamic as people push off against each other to obtain breathing space. In the Cincinnati rock concert incident, a line of bodies was found approximately 9 m (30 ft) from a wall near the entrance. This indicates that crowd pressures probably came from both directions as rear ranks pressed forward and front ranks pushed off the wall.
Experiments to determine concentrated forces on guardrails due to leaning and pushing have shown that force of 30% to 75% of participant weight can occur. In a US National Bureau of Standards study of guardrails, three persons exerted a leaning force of 792 N (178 lbs.) and 609 N (137 lbs.) pushing. In a similar Australian Building Technology Centre study, three persons in a combined leaning an pushing posture developed a force of 1370 N (306 lbs.). This study showed that under a simulated "panic", 5 persons were capable of developing a force of 3430 N (766 lbs.).
Pressure Suit Research Project
The suit (left) measures the pressure, temperature of the subject. Using telemetry we can monitor the crowd state and pressure on the test subjects and barrier system. Coupling this with video analysis we are calibrating the above progressive crowd collapse and shockwave modelling tool.
This research is sponsored by Mojo and Roskilde.
Above - Roskilde 2011 - Orange Stage. Below - 4 of the 6 pressure suits used in this years survey/analysis.
Below - using the calibration grids to assess the pressure differential through the crowd.
Below - fluorescent hats identifying the students
Below - telemetry system monitoring the pressure and temperature of the suits
Below - telemetry system monitoring the pressure and temperature of the suits
Monitoring and modelling pressure in crowds is a complex process involving sensor equipment on the barriers and within the crowds using the pressure suits developed at Bucks New University
Above - crowd modelling tool (3D interactive agent model with force and impact variables).
Below - simulation of a progressive crowd collapse. The modelling tools allows us to simulate and understand the complex dynamics of shockwaves in crowds.