One of the neat things about traffic is how it can be analyzed in terms of some physics parameters. You get density waves that can propagate, and end up getting slowdowns that can persist long after the original cause is gone. Or, as this video shows, there doesn’t have to be a real cause, like an accident or scantily-clad jogger distracting the drivers. Just statistical fluctuation can be enough to send a shockwave through the traffic.
There’s a short article as well
(via Cognitive Daily)
UPDATE: more on this at Backreaction. Actual analysis.
The plot shows nicely how the perturbation – the zone of zero velocity (aka the jam) – travels at constant speed in the direction opposite to the traffic flow.
Cool video.
This is interesting Swans. A little over a year ago, I read about an electrical engineer who studied traffic in his free time and even did a few experiments on freeways with his friends. He found that something like somebody changing lanes abruptly or slowing down could cause “waves” that lasted for hours.
He concluded (and I agree with him) that better driver education would be more effective (and definitely cheaper) than changing road design.
For example, he found that the waves could be stopped if only a few drivers would maintain a slightly slower constant speed and keep distance between them and the car in front of them. Most drivers drive faster when the road is clear and then slam on the breaks when they approach a jam. This is the reason jams keep perpetuating.
I will try to find the link.