The Counterintuitive Science of Traffic Jams

Tom Vanderbilt, author of Traffic, gave a 23-minute talk on the counterintuitive science of congestion at the Boing Boing: Ingenuity conference in San Francisco last month. Turns out a lot of the problems we ascribe to poor roads or other drivers are really our own fault. You can watch the video below:


Brad Plumer, at Washington Post, summarizes the talk:

— Self-driving cars steered by robots could do a lot to reduce traffic jams.That’s because the human inability to maintain a steady, constant speed on the road is responsible for a lot of congestion. Japanese physicists discovered this when they had people try to drive around in steady speeds on a circular road. Jams materialized out of nowhere. People braked erratically and started responding uncertainly to people ahead of them.

— Cars tend to drive closer to bicyclists who are wearing helmets. That comes from Ian Walker, who set up a bicycle with sensors and drove around the city. Vehicles tend to crowd closer to him when he was wearing a helmet than when he wasn’t. That’s not necessarily surprising, but it’s a reminder of all the weird unconscious tics we adopt while driving and making on-the-fly assumptions.

— There are all sorts of fun patterns in who honks their car horns. In what sounds like a exciting job, researchers sat at intersections and refused to move when the light turned green to see who honked at them. Men honk more quickly than women. People with expensive cars also honk more rapidly — although people in convertibles are less likely to honk.

— There are also fun patterns on driver courtesy. Older drivers are more likely to stop for others. Drivers are more likely to be courteous when the other car has extra passengers inside. People also are more likely to violate traffic rules the closer they are to home — a “familiarity effect.”

—  There are all sorts of optical illusions that can trick human drivers. Fog makes objects seem like they’re moving slower than they really are. And experiments show that humans are really bad at judging the speed of an oncoming train at a crossing until it’s nearly arrived. Another point in favor of self-driving cars, perhaps.

—  Congestion often looks tantalizingly easy to clear up — in theory. One study that tracked drivers in Boston during rush hour found that if you could remove just 1 percent of people on the road (say, to mass transit), you could achieve a whopping 18 percent improvement in traffic flow. But  for whatever reason, cities haven’t figured out how to do that just yet.

I can’t wait for self-driving cars.

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