TRAFFIC jams are a fact of life for many car drivers. Every morning millions of drivers around the world sit motionless in their vehicles for long periods of time as they try to get to work, and then repeat the experience on their journeys home in the evening. The same thing often happens when they are driving to the coast for the weekend or to the airport to go on their holidays. They blame other drivers, increasing volumes of traffic and, inevitably, roadworks. So what has any of this got to do with physics?
Well, consider every car as an "elementary particle" that is constrained to move along a one-dimensional trajectory. This particle must also obey certain conditions: for example it must try to get from A to B and it must not collide with other particles! Could the collective behaviour of this complex system be responsible for traffic jams and the various other features associated with traffic flow? Does this behaviour have anything in common with the phenomena of self-organization and pattern formation that have been discovered in recent years? Indeed, should traffic phenomena be considered as part of statistical or nonlinear physics?
In the August issue of Physics World magazine, Boris Kerner of DaimlerChrysler AG in Germany writes about the physics of traffic.