DON鈥橳 panic! Experiments with humans and sheep show that when a group has to move through a narrow opening, they take longer if each individual tries to move quickly.
The so-called 鈥渇aster is slower鈥� effect has been cited as a factor in tragedies such as the 1989 Hillsborough Stadium disaster in the UK and the 2003 Station nightclub fire in the US. But until now it hadn鈥檛 been fully tested.
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Iker Zuriguel and colleagues at the University of Navarra, Spain, put 95 volunteers in a room and asked them to evacuate in three different ways: avoiding all physical contact, allowing soft contact, and allowing gentle pushing. More competition meant a slower escape, they found.
鈥淧eople get stuck in the door,鈥� says Zuriguel. 鈥淭his can be dangerous.鈥�
Next they recruited a flock of hungry sheep. 鈥淪heep are useful,鈥� says Zuriguel. 鈥淭hey are used to pushing each other just for food.鈥� Sheep move more quickly in warmer temperatures, so the researchers compared their speed moving through a doorway on warm and cool days. As expected, individual sheep moved more quickly when it was warm, but the group as a whole was slower to get through the door.
A third experiment showed the same effect with glass beads (Physical Review E, ).
Previous experiments did not allow people to push each other, says Zuriguel, so simulations based on them and used in emergency planning might be unrealistic. The research could help design better emergency exits.
This article appeared in print under the headline 鈥淪heep and humans show shoving makes evacuation slower鈥�
Image: Philip Wallick/Corbis
