This really bugs me.

I get that if something is blocking lanes on a stretch of road that usually carries large volumes at a high rate of speed, a backup will develop because there will still be a high flow of cars slowing down at the end of the traffic backup even as the cars at the front are speeding away from the front. I even understand that during times of heavy volume the backup could stay miles long until a time of day when the volume is less at the back than the rate the cars speed away from the front.

What I don't understand is why the backup sticks around even if there is nothing to look at when you get to the front. This doesn't make any damned sense. Even though the blockage was towed to a wrecking yard, why is the commute screwed until the end of the rush?

Driving, Not Looking

Waves, my friends. Waves. Not only can Science explain; Science can also offer a solution! Killing the ghosts of traffic accidents takes a few drivers not acting like total hyenas when behind the wheel. Good luck with that.

If cars on a road were more like marbles falling down in a tube, we wouldn't have this problem. Pinch the tube and you cause a backup, with marbles piling up above where you're pinching. When you release the pinch, the marbles all start moving at once—returning more or less to the original maximal speed in unison. Cars can't do that—we're too frightened to scratch our paint by bumping into the car in front of us. Cars can only speed off when they can see clear roads ahead, at the very front of the jam. In the meantime, cars are still piling up at the end of the jam. So, after the source of the slowdown is long gone, this wave of slowed-down cars actually moves backward—the front is eaten off as the end rebuilds.

Usually we feel this as stop-and-go traffic. By racing ahead when there are teeny openings, only to slam on the brakes when the cars in front of you slow down, you are perpetuating the wave.

Want to end jams? Drive very evenly, no faster than the average speed of traffic. Focus on staying the same speed, slow enough that you never have to smash the brakes. This means you might have, at times, a huge gap in front of you. This gap will eat up the wave, by acting as a dampener. Just by yourself, you'll devour the traffic jam and make the average speed faster.

About a decade ago, electrical engineer William Beaty tried this on 520 at rush hour. It worked.

Evenly Yours,

Science

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