Stampede!

Scientists want to study stampedes at places like sports arenas and music concerts, so they can figure out how to prevent them. They can’t study actual human stampedes, so what can they do??They stampede mice instead. They’ve discovered that fewer, smaller exits actually enable more mice (and people) to escape.

Gaia Vince writes in New Scientist that experiments on how panicked mice escape from enclosed areas show that they behave in the same way computer models predict humans do. Disasters such as the May 2001 stampede at a football stadium in Ghana that killed more than 120 people, and the February 2003 Chicago nightclub stampede that killed 21 people, have made scientists try to develop models to predict how people will behave when trying to flee.

Caesar Saloma taped 60 mice escaping from a pool of water onto a dry platform, through doors of various widths, and found the mice made the most efficient escapes when their route was only large enough for a single mouse to squeeze through. This prevented them from trampling each other to death and could influence the design of emergency exits in buildings. He says, “Interestingly, we found that the most efficient escape was when the door size was only large enough for one mouse to squeeze through, as it promoted self-organized (lining up). However, as soon as the door width was increased, the mice stopped lining up and competed with each other, which slowed down the overall escape rate.”

He varied the distance between doors as well, and found that if escape doors were positioned too close together, the groups of mice that formed around the exits interfered with each other, slowing them down. “Our results are consistent with the computer models for humans,” Saloma says. “Hopefully our study will help architects design buildings and escape routes that induce people to (line up) and delay jamming. It is not enough to increase the size and number of doors, as it may have the opposite of the desired effect.”

It’s hard to keep something in, if it wants to get out. Learn about the evil uncovered in an ancient Egyptian tomb on this week’s Dreamland.

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