How some traffic jams happen

We’ve all been in situations where the traffic is moving along smoothly and suddenly there is a backup for no apparent reason. Computer simulations suggest that this can be caused simply by one driver slightly braking, causing the driver behind to brake and so on, thus causing something similar to a shock wave being propagated along the line of cars.

Via BoingBoing I came across an actual experimental test of this theory that was done by researchers at the University of Nagoya in Japan. The waves are clearly visible, though the traffic conditions are not as realistic as one might like.


  1. Brownian says

    This fellow theorises that increasing the distance between yourself and the driver ahead of you can mitigate this type of chain reaction. Given enough distance, you’re not likely to tap your breaks just because the person ahead of you does.

  2. RW Ahrens says

    In the DFW area in Texas, we used to call these “Flying Dutchmen”, because they just seem to come out of nowhere and disappear just as fast.

  3. says

    It’s all I can think about while sitting in traffic. I obsess about it. I’ve even thought about quitting my job and going to study physics full time just so I can research traffic, specifically this phenomenon.

    And, of course, find out which IDIOT is to blame. Since there must be somebody to blame. Obviously.

  4. BillyJoe says

    Oh yeah, increase the separation between the 30 cars on that circular track, I’d like to see that!

  5. aspidoscelis says

    That fellow is right. Even once such a traffic jam has started, all it takes is one big gap to end its propagation.

    These things are probably started by those jerks who tailgate…

  6. says

    My husband and I call this the traffic slinky. We ‘compete’ to leave enough distance so as to not have to brake in traffic. We might be a bit weird.

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