When traffic on a highway reaches a certain density and the average distance between cars falls below a certain threshold, then a random perturbation such as one car hitting its brakes (to avoid a squirrel, say) or even just slowing down a bit, causes the car behind (which is too close) to hit its brakes even harder, and the car behind THAT to... and a wave of cars slowing travels backward through the traffic, sometimes bringing the traffic to a complete standstill. Does that help? There is no external cause, it is just the internal nature of the system.
Posted by: Abbas Raza | Mar 9, 2008 5:06:58 PM
This reminds me of the book "Sync" by Steven Strogatz. Individual units, all autonomous, seemingly going about their own business, and then a small input to the system knocks the whole thing into sync. I seem to remember he even talks about traffic in the book...fun stuff.
Posted by: Cyrus Hall | Mar 9, 2008 8:37:28 PM
Here’s a link to the press-release about the study :
which pinpointed the highly elusive and enigmatic real reason behind jamming :
“ The real origin of traffic jams often has nothing to do with obvious obstructions such as accidents or construction work but is simply the result of there being too many cars on the road. “
Another piece of evidence that carpooling or finding alternate modes of transportation (taking the bus!) is better for the rest of us. However, we're not naturally altruistic, especially when it concerns perfect strangers, so unless it gets REALLY BAD, many people (ahem, here in Seattle) will continue to drive their own cars. Alone.
Posted by: ecp | Mar 10, 2008 5:19:30 PM
Interesting but doesn't the fact that it's a closed loop make the results too specialized to be applied to open road traffic? I realize that in the absolute sense "open" is a relative term, but still, normal traffic is several orders of magnitude more open than the closed track that this experiment used.
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Comments
Thanks, I never knew those slow-ups on the freeways actually had a name. Interesting to watch, still can't see the cause as yet.
Posted by: rhbee | Mar 9, 2008 2:32:39 PM
rhbee,
When traffic on a highway reaches a certain density and the average distance between cars falls below a certain threshold, then a random perturbation such as one car hitting its brakes (to avoid a squirrel, say) or even just slowing down a bit, causes the car behind (which is too close) to hit its brakes even harder, and the car behind THAT to... and a wave of cars slowing travels backward through the traffic, sometimes bringing the traffic to a complete standstill. Does that help? There is no external cause, it is just the internal nature of the system.
Posted by: Abbas Raza | Mar 9, 2008 5:06:58 PM
This reminds me of the book "Sync" by Steven Strogatz. Individual units, all autonomous, seemingly going about their own business, and then a small input to the system knocks the whole thing into sync. I seem to remember he even talks about traffic in the book...fun stuff.
Posted by: Cyrus Hall | Mar 9, 2008 8:37:28 PM
Here’s a link to the press-release about the study :
http://tinyurl.com/2r2s93
which pinpointed the highly elusive and enigmatic real reason behind jamming :
“ The real origin of traffic jams often has nothing to do with obvious obstructions such as accidents or construction work but is simply the result of there being too many cars on the road. “
Posted by: Martin g | Mar 10, 2008 4:35:13 PM
Another piece of evidence that carpooling or finding alternate modes of transportation (taking the bus!) is better for the rest of us. However, we're not naturally altruistic, especially when it concerns perfect strangers, so unless it gets REALLY BAD, many people (ahem, here in Seattle) will continue to drive their own cars. Alone.
Posted by: ecp | Mar 10, 2008 5:19:30 PM
Interesting but doesn't the fact that it's a closed loop make the results too specialized to be applied to open road traffic? I realize that in the absolute sense "open" is a relative term, but still, normal traffic is several orders of magnitude more open than the closed track that this experiment used.
Posted by: Pete Chapman | Mar 11, 2008 4:17:43 AM
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