Anyone who lives in a major city knows that traffic is one of those niggling, persistent annoyances. A new study has identified a potential cause: you’re not keeping the right distance from the car behind you. Which sounds like it can’t be your problem since you can’t control the guy that’s staying uncomfortably close to your bumper. True. But mathematical models show that if every car on the road kept the same distance between the car in front of and behind it, traffic would move seamlessly and potentially even twice as fast.
Of course, it’s not that simple, though. Traffic is a great example of emergent property, a philosophical term used to describe the phenomenon of many small things compiling to create something bigger. With traffic, it’s the many individuals cars together forming a complex traffic mess.
That’s because humans bring a lot of variables to the mix. A driver is usually — and rightly — most focussed on the car she’s following, but if she brakes hard the car behind her will have to brake a little harder. If she gets close to another car the density in that one area will cause a slowdown. Mathematical models have shown that at a certain density there are enough variables brought by human reaction time and individual driving habits to cause a traffic jam.
Interestingly, this is a human problem. Ants don’t experience traffic jams; they move as quickly in small groups as they do en masse. Bats are the same. They fly in large groups, each one tracking the bats around him with echolocation. They play follow the leader, even if that leader is in the back of a pack, in an impressive display of group coordination.