Monday, July 05, 2004

Heisenberg on the Autobahn

We would all agree, I think, that what you know about a situation can change how you act in that situation. Can what you know about a situation change the situation itself? German research scientists have developed a next-generation, highly accurate model of traffic on the Autobahn, but it may become a victim of its own success.

This model differs from previous versions by attempting to model "realistic" driver behavior and "realistic" physical aspects of cars. Previous versions permitted "infinite deceleration," meaning they assumed that cars could stop instantly without slowing down first. The new model requires deceleration and acceleration, which allows them to better predict the bottlenecks that lead to jams. The program also models more precisely the behavior of real drivers, some of whom drive more aggressively and some more defensively.

Not too surprisingly, this effort to more closely match the structure of the model to the structure of the real world portrayed by the model has paid off with much more accurate predictions of trouble, up to an hour before the jam stops traffic. But where does Heisenberg step in?

The model's predictions show up on a website with a 90% accuracy rate for likely trouble up to an hour in advance. Smart drivers have started consulting the site before leaving home and changing their behavior in response, so many in fact, that the accuracy of the predictions has begun to slide. Modellers worry that once the data becomes available on cellphones, things will get even worse. They hope to address this Heisenbergian backlash by reducing the amount of information available, in hopes of diversifying drivers' adaptive strategies.

New Scientist

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