From: Crowd disasters as systemic failures: analysis of the Love Parade disaster
Densities are below 2-3 persons per square meter.
Normal operation at low risk.
Regularly verify normal operation, watch out for perturbations. Make sure that the flow does not exceed the safe value of 82 persons per minute and meter.
People accumulate. Certain areas become progressively more crowded.
People slow down due to a bottleneck or stop for some reason.
Limit inflows to ensure that the expected extent of accumulation will not be exceeded. Gather information and determine the reasons for the accumulation. Prepare possible counter-measures. Move enough security to the respective area. Inform the responsible police and emergency units.
Jams of people are forming and growing.
Insufficient outflows may cause serious problems over time (such as high densities), particularly in constraint spaces.
Communicate with the crowd. Promptly take appropriate flow reduction measures such as re-directing people. (Keep in mind that stopping people causes a growing pressure in the crowd and impatience.) Move police and emergency units towards the crowded area(s) in case help will be needed.
Stop-and-go waves occur (this happens only in dense moving crowds). People are pushed.
The continuous flow has broken down. The outflow capacity is considerably reduced. The situation may escalate quickly.
Take suitable counter-measures. Pressure relief strategies (such as opening emergency routes and re-routing inflows) should be taken and people informed about them. Before, any obstacles (such as fences) in the way must be removed. A sufficient number of emergency units and police must be in the critical area and ready take over control in interaction with the crowd management.
People cannot move freely and are squeezed between others. People are pushed around.
A critical density has built up in the crowd. Injuries can easily happen.
Police should take over control in close consultation with the crowd management. Appropriate contingency plans must be applied. Evacuation is strongly advised. Communication with the crowd is crucial. Emergency forces must be in the most crowded areas, in order to provide first aid whenever needed.
People disrespect fences or try to get out of the area.
The situation is critical and likely to get out of control.
Communicate with the crowd and evacuate it. Provide help and first aid. Inform hospitals and additional emergency units about the possibility that the situation may get out of control.
Crowd turbulence occurs. People scream or shout for help.
Injuries and fatalities are likely. A crowd disaster can happen any time.
Calm down the crowd and guide it. Continue to evacuate people. Watch out for the areas with the highest densities and largest crowd movements, to ensure support and first aid. Additional emergency vehicles must be called to ensure sufficient manpower, and hospitals must be informed about likely (and potentially many) injuries.
People are falling to the ground. People raise arms into the air.
People are in big trouble. Many injuries are to be expected. A crowd disaster is (most likely) happening.
Immediate help and first aid are needed, probably for many people. Hospitals must be prepared to shift from routine to large-scale emergency operation.
People crawl over others.
A crowd disaster has probably happened.
Apply rules for a state of serious emergency.