September 23, 2003

Panicking mice find flaws in exit routes

Rodents hint at how people flee from a crowded room.

by Philip Ball
Nature News

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Panic-stricken mice are hinting at how people fleeing a confined space can hinder each other's escape. The animals could help to test computer models of crowd-control measures.

Caesar Saloma and colleagues at the University of the Philippines in Quezon City watched mice escape through doorways in a flooded chamber. Mice have a strong impulse to avoid water, so the researchers placed their rodents in a flooded cell with one or more exits onto a dry platform.

Faced with a narrow door, mice form a kind of queue and make a relatively orderly escape, they find. Wider doors cause the animals to block one another, making their getaway sporadic and inefficient1. Escape is also erratic when there are several doors, as crowds around one can obstruct the next.

Crowd panic is notorious for turning accidents into disasters - as happened, for example, on 15 April 1989 at Hillsborough football stadium in Sheffield, UK, when 96 people were crushed to death.

In the past few years, scientists have devised computer models to help architects and emergency services to simulate such situations2. For example, Michael Batty and colleagues at University College London used such models to propose routing and crowd-control measures for London's Notting Hill Carnival, in which up to a million people congregate in an urban area of just three square kilometres3.

But the models are difficult to test - there are, as Saloma's team puts it, "ethical and even legal concerns" involved in triggering alarm in a roomful of people. Mice, they argue, can stand in for human subjects without being harmed.

Like us, mice fleeing from life-threatening danger look for the exit and make for it, pushing others aside if necessary. What's more, like panicking humans, the animals tend to follow one another rather than assessing the best exit route.

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