In a jam

The goal of intelligent transportation systems is straightforward: Keep traffic moving.

Traffic jams, as everyone knows, tend to be self-propagating. The more cars that are stopped, the longer it takes to get traffic flowing again, which means more cars end up in the mess.

In the case of accidents, the rule of thumb is that every minute spent clearing one from the roadway leads to four to six minutes of delay for drivers. Weather, including ice or floods, also can bring traffic to a stop.

If, on the other hand, drivers know ahead of time about a slowdown in their path, they can find an alternate route. ITS makes it possible to gather traffic and weather data, analyze it and deliver it to drivers — via Web sites, electronic signs, dashboard displays, handheld computers or even telephones.

And it's not just passenger cars. States are working on applications for police and other public-safety agencies, maintenance crews and commercial trucking companies.

ITS also includes such applications as automated tollbooths, which enable drivers to attach the equivalent of a debit card to their car and have the toll deducted as they drive through. Again, it's a matter of keeping trafficon the go.