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Wednesday, 27 September, 2000, 18:06 GMT 19:06 UK
Equation predicts crowd panic
Pop concert PA
People in crowds follow a herding instinct
A new computer model that predicts how panicking crowds behave could lead to the design of safer stadiums, public buildings and transport systems.

Scientists in Germany and Hungary developed the program to explain how people move when pushed together during a fire or another emergency.

They claim it could be used to test the ability of corridors and exits to cope with emergencies.

The researchers say their new, more realistic approach is based on calculating the ways individuals react in a crowd rather than assuming people move as an unthinking mass.

The method relies on an enormous number of individual calculations, something that has only been possible recently with the increase in computer power.

Herd instinct

Psychologists have shown that people act in certain ways in crowds.

Under normal conditions, when they go through a doorway for example, individuals tend to move steadily and avoid collisions.

But when panic strikes, a particular form of "herding" behaviour sets in.

As people try to move faster, jams build up, and may eventually cause pressures capable of bending steel barriers or pushing down brick walls.

Because people tend to follow others, alternative exits are often ignored, sometimes with tragic consequences.

The researchers used these observations to develop an escape panic computer model, taking into account a mixture of social, psychological and physical forces influencing the behaviour of crowds.

Crowd survival

The program was used to investigate how crowds behave in various situations, such as 90 people trying to escape a smoky room.

In this scenario, individuals speed up and block an exit they would pass through safely at normal walking speed.

"This effect is particularly tragic in the presence of fires, where fleeing people can reduce their own chances of survival," said the researchers, reporting their findings in the journal Nature.

Columns placed asymmetrically in front of the exits to prevent build-up might ease this, they said.

They also found that widening a corridor may actually slow down movement because people try to overtake, then have to squeeze back into the queue when it narrows again, creating a jam.

The authors, based at the Collegium Budapest-Institute for Advanced Study, Hungary and Dresden University of Technology, Germany, believe the information could be used to work out low-risk designs for the width of corridors, the number and position of doors and the size of communal areas.

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06 Apr 99 | Sci/Tech
Mathematics of the crowd
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