The Madness of Crowds

Set your emotional dial, for a moment, to panic: Someone shouts “Fire!” in a crowded theater. Your hands tremble, your pulse a race, a cold sweat spreads across your back. You’re trapped with hundreds of others. What would you do to escape? Scientists and architects think they know. They have long had mathematical models that predict crowd behavior, but testing was always a problem, until now. In an article in the Proceedings of the National Academy of Sciences, researchers simulated a mass exodus by dropping mice into a tub of water. The models held up. The mice? Don’t ask. – Thomas Hayden

Herding 

• What happens: Disaster gives voice to your inner sheep; people follow a crowd to an open door even if other exits are clog-free.
• Cause: Most people head for the door they used to get in. The Rhode Island nightclub that burned years ago had four exits, but most of the bodies were found around the front door.

• How you’ll die: A fleeing crowd pushes as one; the resulting pressure is like a back-walk massage from a sumo wrestler. Ribs crack, organs squish, and the air squirts out of your lungs like ketchup from a foil packet.
• The fix: Scope out a couple of alternate escape routes before disaster strikes – why do you think the nice flight attendant shows you the exits on the airplane?

Image via Wikipedia

Pedestrian Arch Formation

• What happens: It’s the Three Stooges effect: The door is wide enough for only one, but everyone wants to be first. More stooges give you a semicircle of gridlock as everyone seeks the shortest straight-line vector to the exit.
• Cause: People are sticky – they wedge into the area in front of the doorway like a cork. The exit clogs, with intermittent bursts of escapees when force exceeds friction.
• How you’ll die: Trapped behind injured neighbors or a doofus who insists others go first, you’ll be jostled in place like a grain of sand in an hourglass.
• The fix: A column a few feet in front of the exit can help break up an arch, splitting the jam into smoothly flowing streams. Being first in line helps, too – lingering near the exits during a show isn’t just cool; it can save your life.

Disruptive Interference

• What happens: Two doors, two pedestrian arches – if they overlap, chaos ensues at the junction.
• Cause: Your eyes are on the exit, not the bodies in front of you.
• How you’ll die: In a fire, if the crushing doesn’t get you, toxic gases probably will. The poisonous-fume hit parade includes carbon monoxide and super-deadly phosgene. “One or two whiffs of phosgene and you’re down,” says one firefighter.
• The fix: Two doors are better than one, but arches can spread all the way across narrow rooms. Architects should put doors at opposite ends of the room. And if you’re in the scrum, try not to freak out. The exit throughput rate drops as the panic level climbs.

Wall Seeking

• What happens: Some of the herds peel-off on their own; they end up creeping along the edges of the room.
• Cause: Rugged individualists know that in the midst of a panic, the mob is the worst place to be. They also know that walls are inevitably interrupted by exits.
• How you’ll die: Scared and alone. If you miss the exit or go the wrong way along the perimeter, whatever you’re running from will get you. If too many individualists have the same plan, you’ll bump into them, slowing your escape.
• The fix: Better exit indicators – bright, flashing lights at exits and along floors; public address systems; and loud electric horns.