The scientific reason why there are traffic jams

In a twenty-three minute overview, Traffic author Tom Vanderbilt explains in layman’s terms some of the reasons why traffic jams occur, and how in some ways, we can easily prevent them. I mean, who would want to actually sit in traffic? It’s horrible, so hopefully just having this knowledge will help ease congestion.

In the talk that Tom gave, the underlying theme is the problem with traffic is us. That’s right, there is nobody else driving these cars other than us humans. We are the problem, and are to blame. I can come to terms with that, I think subconsciously we already knew that. But why?

As it turns out, a lot of traffic jams have to do with perception, and the human nature of being too darn kind. For example, there is the “zipper” merge technique, as explained by The Atlantic.

Road work often reduces two lanes of traffic down to one. In these situations, American drivers typically merge into the right lane as soon as possible and form one long line. The main reason they do this is because people think it’s bad behavior to stay in the left lane and merge late.

In fact, says Vanderbilt, traffic would be much better off if cars stayed in both lanes then merged at the very end, one by one, like a zipper. It’s safer (fewer lane changes), it reduces back-ups (often up to 40 percent), and it quenches road rage (still on the rise). The zipper merge is used in Germany but can’t overcome its bad reputation in the United States. A trial in Minnesota failed because drivers wouldn’t stay to the left. They were too nice.

A big reason for traffic is that too many cars are trying to occupy too little space on the road. But that’s not the only problem. A human inability to maintain a steady speed and following distance on the highway makes traffic a lot less smooth than it could be.

A few years back a group of Japanese physicists gathered drivers on a closed loop course and asked them to keep a certain speed and following distance. They couldn’t do it. After a while the system broke down, and a reverse shock wave rippled back through the whole line of cars. Vanderbilt thinks autonomous cars, like Google driverless cars, will help reduce this problem considerably.

Visibility, and how our brains interpret objects, also play a large role in contributing to traffic. Think of fog, rain, and other driving conditions that we may come across on the roads day to day. These situations play tricks on our brains, and our eyes. In the example Tom gives with fog, in a study done in Australia, two driving scenarios were given. One without fog, and one with fog. Both cars were going at the same rate of speed. However, in the foggy scenario, our brains were tricked into thinking we were going slowly, giving us a false sense of depth and visibility.

Tom also thinks that if more drivers move off the roads to mass-transit, that will also help solve the problem. Which I agree with, however, with rising costs of transit (parking costs and high ticket fees), more and more people are less likely to take mass-transit and just risk it on traffic jammed roads.