Sep 15, 2011 6:34 PM GMT
If cars broadcast their speeds to other vehicles, a simple in-car algorithm could help dissolve traffic jams as soon as they occur, say computer scientists. [..]
One interesting question is how best to dissolve jams once they form. Most traffic experts agree that the basic idea is to ensure that cars leave the jam more quickly than they arrive, so that the jam dissolves.
Now Hyun Keun Lee and Beom Jun Kim at the University of Seoul in South Korea have a come up with a simple idea to automate and improve this dissolving process. They define two types of drivers: optimistic and defensive. Defensive drivers leave more room to the vehicle ahead than required by safety. Optimistic drivers leave too little.
They then use a cellular automaton to model traffic flow in a way that reproduces most of the usual driving behaviours such as exceeding the speed limit, overreacting to road conditions by accelerating and braking to hard and so on.
But they also add an extra ingredient. All the vehicles in this model share their speed and position with their neighbours and this information filters downstream. That means downstream vehicles immediately become aware that the traffic ahead has come to a standstill.
When that happens, Lee and Kim's algorithm immediately switches all the downstream driving behaviour to defensive, so that vehicles exceed the safe distance between them. This slows the rate at which vehicles join the jam.
At the same time, vehicles leaving the jams are made to accelerate away quickly using automated cruise control. This increases the rate at which vehicles leave the jam.
The result is that the jam quickly dissolves.