Ants show that emergency exits can work better when they’re obstructed
1–10 of 18 posts
Re: Ants show that emergency exits can work better when they’re obstructed
#2That's interesting. I once took a sociology class about the behaviour of panicking crowds and we covered exactly this phenomenon, that is, if you put a pillar in front of the emergency exit (without completely blocking it, of course), panicking people can get out faster. It seems counterintuitive but it's been shown numerous times.
Re: Ants show that emergency exits can work better when they’re obstructed
#3Simulate the scenario with water in a pool with a tiny pipe opening at the bottom if the pool leading down. The water will shoot out with a high velocity this means the pressure in the pipe will be higher than pressure in the pool. If you apply this analogy to people and exits, it means that the people directly in the exit hallway( the pipe ) will experience a high change in speed, and since people aren't fluid, friction, thus making their escape more difficult.
Re: Ants show that emergency exits can work better when they’re obstructed
#4That's interesting. I once took a sociology class about the behaviour of panicking crowds and we covered exactly this phenomenon, that is, if you put a pillar in front of the emergency exit (without completely blocking it, of course), panicking people can get out faster. It seems counterintuitive but it's been shown numerous times.
It basically reduces deadlock chance.
When you have one exit and it's blocked due to many people attempting to fit at once, the entire queue is congested.
That barrier turns one exit into two exits (even if it's backed by only one real exit). If one is congested, people can still flow through the other one, and vice versa.
This explains why the evacuation rate is roughly twice faster.
If the barrier is designed to even more virtual exits, it'll be even faster.
And there's an even faster way, that requires no architectural changes, but people will have to be trained in it so well, that they'd follow it even in panic.
And this would be some heuristic which orders people in an unambiguous way, so only one person is attempting to exit at a given moment.
I don't know, left to right order, split in rows, people holding hands... Some creative solution is required to decide what that heuristic would be.
Queues have no congestion, so they'll represent the fastest possible rate of evacuation through a single exit.
Re: Ants show that emergency exits can work better when they’re obstructed
#5Simulate the scenario with water in a pool with a tiny pipe opening at the bottom if the pool leading down. The water will shoot out with a high velocity this means the pressure in the pipe will be higher than pressure in the pool. If you apply this analogy to people and exits, it means that the people directly in the exit hallway( the pipe ) will experience a high change in speed, and since people aren't fluid, fric…
The pressure in the pipe is the same as the pressure in the pool. Additionally, the meter^3/minute is the same in the pool in the pipe, but the with the pipe, the meter^2 is much smaller. So, to keep the same rate of fluid, the meter/minute (speed) has to be much higher.
Re: Ants show that emergency exits can work better when they’re obstructed
#6I remember watching once a TV show (perhaps in the old days of Discovery Channel) about experiments with obstacles put in front of elevators, so people wouldn't clutter in front of it and IIRC they have found the same thing back then. I wish I had magic skills to find a video of that show.
Re: Ants show that emergency exits can work better when they’re obstructed
#7That's interesting. I once took a sociology class about the behaviour of panicking crowds and we covered exactly this phenomenon, that is, if you put a pillar in front of the emergency exit (without completely blocking it, of course), panicking people can get out faster. It seems counterintuitive but it's been shown numerous times.
It basically reduces deadlock chance. When you have one exit and it's blocked due to many people attempting to fit at once, the entire queue is congested. That barrier turns one exit into two exits (even if it's backed by only one real exit). If one is congested, people can still flow through the other one, and vice versa. This explains why the evacuation rate is roughly twice faster. If the barrier is designed to ev…
"And this would be some heuristic which orders people in an unambiguous way, so only one person is attempting to exit at a given moment."
Given how badly people behave at four-way stop signs (where there's an unambiguous ordering algorithm that most drivers seem to ignore), I don't think there's much hope for a heuristic ordering working well for panicked crowds at emergency exits.
Re: Ants show that emergency exits can work better when they’re obstructed
#8Great post! I gained useful insights from this. Thanks!
Re: Ants show that emergency exits can work better when they’re obstructed
#9That's interesting. I once took a sociology class about the behaviour of panicking crowds and we covered exactly this phenomenon, that is, if you put a pillar in front of the emergency exit (without completely blocking it, of course), panicking people can get out faster. It seems counterintuitive but it's been shown numerous times.
It basically reduces deadlock chance. When you have one exit and it's blocked due to many people attempting to fit at once, the entire queue is congested. That barrier turns one exit into two exits (even if it's backed by only one real exit). If one is congested, people can still flow through the other one, and vice versa. This explains why the evacuation rate is roughly twice faster. If the barrier is designed to ev…
That's not really a great description of what's happening. The group in-front of the exit is moving vary slowly and everyone needs to accelerate before the exit. By limiting things to two lines people are moving faster as they approach the point of maximum contention so they don't need to accelerate as much. On top of this you add delays as people content left right or center at the exit.
Re: Ants show that emergency exits can work better when they’re obstructed
#10Simulate the scenario with water in a pool with a tiny pipe opening at the bottom if the pool leading down. The water will shoot out with a high velocity this means the pressure in the pipe will be higher than pressure in the pool. If you apply this analogy to people and exits, it means that the people directly in the exit hallway( the pipe ) will experience a high change in speed, and since people aren't fluid, fric…
The pressure in the pipe is the same as the pressure in the pool. Additionally, the meter^3/minute is the same in the pool in the pipe, but the with the pipe, the meter^2 is much smaller. So, to keep the same rate of fluid, the meter/minute (speed) has to be much higher.
http://en.wikipedia.org/wiki/Bernoulli's_principle
Where velocity increases, pressure decreases.