Giving Drivers Enough Data To Avoid The Worst Traffic Jams.(The Technologist)

Byline: Jesse Ellison

DRIVERS IN ATLANTA, GEORGIA, spend an average of 60 hours a year stuck in traffic on their way to and from work. During these delays, they waste 40 gallons of gas per person and spew tons of carbon into the atmosphere. With Atlanta sprawling larger all the time, engineers at the Georgia Department of Transportation began wracking their brains for a solution. Better informed drivers, they reasoned, would be able to avoid traffic snags. The problem was finding an inexpensive way of keeping track of how many cars are on the road at any given moment, and where.

Making traffic flow more efficiently isn't just a problem for car-obsessed America: cities all over the world have struggled with it. Most high-tech solutions usually involve putting myriad cameras and sensors on the highways and back streets, which makes them expensive. Georgia, for instance, had already expanded the traffic monitoring system it created for the 1996 Olympics to about 225 kilometers of roadway. Underground fiber optic cables linked together 1,400 traffic monitoring cameras, and electronic signs directed drivers around traffic tie-ups. But the system costs $1 million per mile to build, and it needed constant repairs as vehicles struck equipment, storms took down cameras, and workers dug up cables.

To keep track of cars without having to build a lot of new infrastructure, Georgia's engineers turned to a transmitting device that already exists on almost every car on the road. It's called the cell phone.

As long as a mobile phone is turned on, it continuously sends signals to local cellular towers so that the telephone company -- in this case, Sprint/Nextel -- knows where to route your calls. The phone company provides this information, raw, to AirSage, a traffic-monitoring firm in Atlanta, which lays the information over a digital map. Commuters log onto a Web site to see real-time travel speed and congestion information gathered anonymously from thousands of drivers, or they can get automated e-mails or text messages about traffic conditions along a particular route.

When the city officially incorporated the cell-phone information into its traffic Web site in July, the number of kilometers covered jumped to 764. Getting ...