Unlocking the mysteries of the random traffic jam

Posted by freedomforall 11 years, 3 months ago to Technology
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Have you ever seen a 2-mile long traffic jam on the opposite side of the highway and thought, “Gee, I didn’t see an accident back there, I wonder what happened?”

Or maybe you are cruising along at 60 mph and suddenly you slow to a stop. You then sit stationary for 30 seconds and just as quickly you are back to cruising at 60. What happened?

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  • Posted by Robbie53024 11 years, 3 months ago in reply to this comment.
    Or, the idiot who moves from one lane to another with too little room, causing the driver of the car following to brake, and then the cascade begins. I have used a mathematical simulator to show that if as few as 2% of drivers change lanes - at any speed - that all arrive at a slower rate than if all stayed in their initial lane.
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  • Posted by Non_mooching_artist 11 years, 3 months ago
    I call it the "RBT", or Random Braking Technique. When a stupid person, usually in the left lane, just hits the brakes for some random reason, slowing things down just enough so the people behind must now tap the brakes... This leads to traffic for no good reason.... And causes my head to explode...
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  • Posted by $ allosaur 11 years, 3 months ago
    Now I can say "jamiton" when this happens in the Birmingham area, especially on I-65 which runs north and south through the west side of the main city. The suddenly slowed down line of traffic will just speed back up after a few minutes for no visible rhyme or reason.
    By the way, I-65 passes through an intersection with I-20/59 that TV and radio reporters have long called "malfunction junction." Years apart, I've seen two cars spin out there in the rain and crash against a guard rail. There a tractor-trailer truck changing lanes ran me off the road and I just barely stopped before a parking lane ended with a concrete barrier.
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  • Posted by JanelleFila 11 years, 3 months ago
    I got stuck in traffic last night, completely stopped as I tried to merge on the freeway. I thought for sure there was a nasty accident. About a mile ahead the construction dropped the highway from two lanes to one lane. As soon as I passed the merge into one lane, everything sped back up. I've never understood why that backs traffic up so badly. I personally think it is because people ignore the signs and wait to the very last minute to merge out of a closing lane.
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  • Posted by $ Snezzy 11 years, 3 months ago
    Anyone who has studied fluid mechanics has pondered over whether the equations for motion of particles in fluid flow might also apply to highways.

    A related phenomenon is the understanding among police that the very last car in a bunch of cars can be seen driving faster than the first car. How can this be possible? Well, the last car is the recipient of the slowing-down and speeding-up that occurs in the middle of the bunch. So at some point he may be going quite a bit faster, to catch up with the rest of them. Also, as the very last one, he's easier to pull over and ticket.
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  • Posted by edweaver 11 years, 3 months ago
    Yup and it usually turned out to be something that people were rubber necking at. It is frustrating when you have somewhere to be.
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