The goal of the experiment was to prove that the GPS-enabled mobile phones could be used to monitor the real-time traffic information.

The students from the University of California drove one hundred cars, equipped with Nokia’s N95 phones, on a 10-mile stretch of highway near San Francisco. During the experiment, special software on the mobile devices periodically sent anonymous speed and location readings from the integrated GPS to servers.

The software is capable of dissociating that data from an individual device and combines it with the general stream of traffic data. The GPS feeds were then combined to create a real-time picture of traffic speeds and projected travel times.

Also, the privacy of the GPS users is protected, because the data is anonymous aand protected by banking-grade encryption.

"Mobile device users control the service. If an individual does not want their device to transmit position data they turn off the feed from their GPS," stated Quinn Jacobson, Research Leader at Nokia Research Center, Palo Alto.

Besides speed and location, GPS-equipped cell phones systems could help provide information on other situations, from multiple side-street routes in urban areas to hazardous driving conditions or accidents on vast stretches of rural roads, the researchers said.

The researchers believe that fewer than 5% of drivers need to contribute location data for the system to be effective on any particular highway.

For state transportation agencies such as The California Department of Transport (Caltrans), tapping into the vast network of mobile phones on the road could one day remove the need to invest in expensive infrastructure to obtain traffic information as well as greatly expanding the coverage of such services.

"There are cell phone-based systems out there that can collect data in a variety of ways, such as measuring signal strength from towers and triangulating positions, but this is the first demonstration of this scale using GPS-enabled mobile phones to provide traffic related data such as travel times, and with a deliberate focus on critical deployment factors such as bandwidth costs and personal privacy issues," said Thomas West, director of UC Berkeley's CCIT.

In the USA alone congestion causes 4.2 billion hours extra travel every year and the purchase of extra 2.9 billion gallons of fuel for a congestion cost of USD 78 billion.