Crash course
Page 3

...It turns out that if everyone were the same, traffic would be more chaotic — all drivers would see that their lane is closing and try to merge out of it at the same time, for instance. So naive models get more congested quicker because drivers all act alike, and because they all act dull.

There are other realities beyond driver personality that a good model can grapple with. University of Leed’s DRACULA traffic model features some of the same individual driving differences as DynaMIT, and also lets drivers plan their own route to the destination. The simulated drivers learn, remembering results from one trip to the next, and experiment to find better routes. H. Michael Zhang at University of California Davis has a model in which every driver behaves the same, but the identical automatons will drive differently depending on whether the surrounding traffic is accelerating, coasting, or braking. Basically, Zhang's simulated drivers can get nervous, or impatient. So the importance of human frailty is a key for his model, too.

Such models can do more than just satisfy scientific curiosity about why traffic behaves as it does – they can help planners design roads, and maybe help workers plan their commutes. In the summer of 2004, a team from University of Duisburg-Essen put their traffic model to work, creating a predictive map of metropolitan Cologne. The model highlights congested areas up to an hour in advance. It's on the web, and more than a hundred thousand people look at it each day to find out what their drive to or from work will be like. This may be what the future looks like, in more ways than one.

So will Boston ever have traffic forecasts, instead of these traffic “nowcasts” that only tell us what has already gone wrong? That’s up to the city and state traffic authorities who run the traffic monitoring and operations center in South Boston. Testing of DynaMIT in Irvine and Los Angeles is under way, and the results may give Boston’s traffic managers enough confidence to start forecasting your morning drive.

For now, DynaMIT, with its “behavioral realism,” shows that we should be grateful that we’re all different. Although the rudenesses or pokey behaviors will continue to annoy us, we can take...