If you’ve ever been caught in the crush of a crowd at a sports stadium you’ll have wondered if there is a faster way to get people out of an exit. Well, it turns out there is, and the simplicity of the method might surprise you.

A collaboration between an insect scientist and engineers has found that, remarkably, placing a post in front of and set back slightly from the exit is the answer. It seems counter–intuitive: surely putting a blockage near an egress would make things worse. But in fact the opposite is true: the post slows people down slightly, allowing a smoother and ultimately faster flow of the crowd through the exit.

TRANSCRIPT

Narration: It’s a nightmare situation. A panic is triggered in the crowd and people run. The exits quickly become blocked and victims are crushed by the enormous mob pressure.

Sporting grounds can be dangerous places when the panic’s on because of a riot or a fire…there are a lot of people and only narrow exits. So here’s the question: is there a faster way to get a crowd out of an exit - and therefore save lives? Researchers are studying crowd behaviour in an attempt to find an answer.

Graham Phillips: Now the first issue the scientists had to deal with is how do you actually study crowd behaviour? You could light a fire in the corner of the stadium here and see what people do but of course there’d be the odd ethical problem with that. And when you ask people to just pretend there is a fire it’s just too fake, so the researchers had to come up with a smarter way.

Narration: A computer simulation is one possibility. Engineers can mathematically model how people are likely to move in any congested situation.

Associate Professor Martin Burd: These computer models are based on equations that describe the movement of individuals: the speed with which they move, the speed of their intended movement, but also the way they interact with other individuals within the crowd.

Narration: Put a crowd in a stadium…build in an exit… then start a panic at the other end. Engineers simply watch the crush form.

But the trouble is, living creatures are more than theoretical idealisations.

Associate Professor Martin Burd: You never want to rely entirely on the mathematics before you scale it up and apply it in a human situation.

Narration: There are lots of details the models don’t include. They assume everyone in the crowd is equally able for example.

Nirajan Shiwakoti: Some people might be old, young, some might be children you’ve got to consider those factors.

We need to predict as much as possible how people behave in real conditions.

Narration: So zoologist Martin Burd joined forces with Engineer Nirajan Shiwakoti, to try something very different. Humans are not the only creatures who live in crowds.

Narration: There are insects that rub shoulders with the hordes on a daily basis, just as we do. They’re not people, but these real living creatures are more than equations at least. They do come with varying abilities and ages, for example.

Martin and Nirajan decided to study the common old Argentine ant.

Associate Professor Burd: They’re a social organism, so they naturally gather in crowds the way humans do. And so we can use them as a good test model in that way. Plus the convenience of using the them. They’re small, easy to keep, and we can find them anywhere: just dig them up in the gardens of the university grounds.

Narration: It’s just a matter of putting the ants in a sports stadium.

Graham: So basically this dish is simulating a stadium kind of situation.

Associate Professor Burd: Exactly. And we have a small exit. It’s just wide enough for one ant to get through. Two ants, not quite wide enough.

Graham: They’re sort of shoulder to shoulder trying to get through.

Narration: To simulate a fire, Martin will squirt in a smell the ants can’t stand – citronella.

Graham: OK. Lets cause a bit of panic and mayhem

Associate Professor Burd: Let’s do it.

Graham: Oh look at that! It has a pretty instant effect, they don’t like that stuff!

Associate Professor Burd: No, they don’t like it. I can see they’re running around panicking.You can see them coming out of the exit.

Graham: I mean it looks realistic. It looks like a crowd of people.

Associate Professor Burd: It’s a crowd of people.

Narration: Now here’s an interesting finding. The computer models predict, a faster way to get people out of an exit, is to put a post in their way.

Associate Professor Burd: Completely counter intuitive. It’s obscuring or obstructing the exit. But in fact it increases the total rate of flow out that exit.

Narration: Could this be true in a real life situation?

Martin decided to test the post theory on his ants.

Remarkably, these guys do now get out more quickly. And the explanation’s intriguing.

Associate Professor: A very typical situation in an enclosed area where people have to exit out a doorway or out some very small corridor, is that everyone rushes at hight speed towards the exit and forms a jam. And that jam typically takes the form of an arch. And an arch is a very stable configuration. Now eventually that arch can break up of course but if it slows people down by even a few seconds that can be the difference between survival or not.

Narration: The post helps prevent an arch of people forming.

Now, there needs to be more research before pillars can be recommended for all stadiums. But it may not be long before you see posts installed at a sports ground near you.

Story Contacts

Associate Professor Martin Burd  

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Nirajan Shiwakoti  

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