Using GPS to Accelerate Highway Traffic
Using GPS data to estimate prevailing speeds and travel times, researchers have been able to obtain a picture of real-time traffic conditions. Current traffic monitoring systems mostly rely upon pavement-embedded sensors, roadside radar or cameras. The high cost of installing and maintaining such systems has restricted their coverage to only limited stretches of highway.
GPS systems, on the other hand, are becoming ubiquitous and are relatively cheap. The technology can pinpoint a car's location to within just a few feet and calculate its speed to within three miles per hour. Enlisting GPS-equipped mobile phones into traffic monitoring systems could help provide information on everything from multiple side-street routes in urban areas to hazardous driving conditions or accidents on vast stretches of rural roads, the researchers say.
"Even though the phones are capable of sending their position and speed every three seconds, an efficient traffic monitoring system should not need to transfer such a large amount of data, which would require enormous bandwidth," says Alexandre Bayen, a University of California, Berkeley, assistant professor of systems engineering and civil and environmental engineering. "Our challenge is to find the optimum subset of this data for effective traffic monitoring," Bayen observes. "The quantity and quality of data provided by GPS-equipped cell phones present an unprecedented enhancement to mobility tracking technology and traffic flow reconstruction mechanisms."
Yet such a system also raises questions about phone users' privacy. That's why the researchers, with the help of Rutgers University's Winlab, have built privacy protection into the system. "Mobile device users control the service--if an individual does not want his or her device to transmit position data, he or she can turn off the GPS feed," says Quinn Jacobson, a researcher with the Nokia Research Center. The system's data is immediately disassociated from individual phones and is combined with the general stream of traffic data. "Only anonymous aggregated data is ever created, transported or stored in this 'privacy-by-design' system," Jacobson notes. All data is further protected by encryption.
A commercial launch date hasn't yet been announced for the system. But when it does become available, its benefits could be substantial. In the U.S. alone, traffic congestion leads to 4.2 billion hours in extra travel time and an extra 2.9 billion gallons of fuel burned, for a total cost of $78 billion, according to a 2007 report from the Texas Transportation Institute. With the number of vehicles on the road increasing rapidly worldwide, a cost-effective method of travel planning could help drivers make smarter decisions about which routes to take.
