Why Traffic Jams Happen for No Apparent Reason

We all know it, traffic jams that seem to happen for no apparent reason is one of the biggest source of frustration for drivers. I can definitely relate to that. Fortunately, dear fellow drivers, our frustration now has an explanation! The phenomenon has recently been re-created for the first time on a test-track by a team of Japanese researchers. Check out the following video report from NewScientist for all the details

Researchers from several Japanese universities managed the feat by putting 22 vehicles on a 230-metre single-lane circuit (see video).

They asked drivers to cruise steadily at 30 kilometres per hour, and at first the traffic moved freely. But small fluctuations soon appeared in distances between cars, breaking down the free flow, until finally a cluster of several vehicles was forced to stop completely for a moment.

That cluster spread backwards through the traffic like a shockwave. Every time a vehicle at the front of the cluster was able to escape at up to 40 km/h, another vehicle joined the back of the jam.

The shockwave jam travelled backwards through the ring of vehicles at roughly 20 km/h, which is the same as the speed of the shockwave jams observed on roads in real life, says lead researcher Yuki Sugiyama, a physicist in the department of complex systems at Nagoya University.

[Via NewScientist]

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6 Responses to Why Traffic Jams Happen for No Apparent Reason

  1. Ok, so they were able to re-produce it, but the video was too short, and it didn’t say their hypothesis for WHY it was happening or perhaps..I don’t know..a SOLUTION???

    It is “comforting” to know they were able to reproduce the phenomenon in a “test conditions” setting…but is there more to this research piece? Perhaps a longer article or video?

    (I commute the 91 freeway in Southern California and am subjected to this “shockwave traffic jam” on a daily basis…would like to know more :P)

  2. I’ve known this for YEARS. I don’t see how this is news or required a test to confirm it. Just drive down any major highway in rush hour and pay attention. Want to cause a BIG traffic jam? Park a police cruiser on the side of the road, and as everyone tries to slow down from 7 – 10 over the limit to the limit itself, it causes complete chaos.

    J.Ja

  3. Ok, so they were able to re-produce it, but the video was too short, and it didn't say their hypothesis for WHY it was happening or perhaps..I don't know..a SOLUTION???

    It is "comforting" to know they were able to reproduce the phenomenon in a "test conditions" setting…but is there more to this research piece? Perhaps a longer article or video?

    (I commute the 91 freeway in Southern California and am subjected to this "shockwave traffic jam" on a daily basis…would like to know more :P)

  4. I've known this for YEARS. I don't see how this is news or required a test to confirm it. Just drive down any major highway in rush hour and pay attention. Want to cause a BIG traffic jam? Park a police cruiser on the side of the road, and as everyone tries to slow down from 7 – 10 over the limit to the limit itself, it causes complete chaos.

    J.Ja

  5. This was studied by Berkeley students in the ’80s. Using Bay Bridge data it was found that traffic maintains a memory of incidents for hours after clearing.

    Maybe these scientists should have done some research on prior studies before wasting time and money to reinvent the wheel.

  6. This was studied by Berkeley students in the '80s. Using Bay Bridge data it was found that traffic maintains a memory of incidents for hours after clearing.

    Maybe these scientists should have done some research on prior studies before wasting time and money to reinvent the wheel.

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