"Smart highway" initiatives may not take cars off the roads, but they will make traffic flow more efficient, according to an April 26 Associated Press report. One such federally funded program tracks traffic congestion using Global Positioning System devices in cars. This project, funded by a $1.3 million grant from state and federal highway officials and headed by Rensselaer Polytechnic Institute's Center for Infrastructure and Transportation Studies, focuses on information collected from commuters on weekday mornings. In February, 200 volunteers who commute daily were loaned a GPS unit and a handheld computer linked to a central server. Drivetime information is sent each minute from each vehicle to a server, where it forms a picture of traffic flow around a 40-mile radius. Speed is computed by tracking progress between virtual checkpoints. The handheld computers send updates. Each handheld displays a map and also suggests alternative routes via a synthesized voice. Drivers act as highway probes, receiving continual feedback from the in-car computer. Project head George List says 10 to 15 percent of drivers in a given area would need to participate to make the system effective. The devices bought separately cost about $1,000. The system would be cheaper than investing in a series of pole-mounted cameras or road sensors, according to the AP report. GPS is one of several technologies being studied by transportation officials and private companies looking to update traffic systems, the AP report said. AirSage, an Atlanta-based company, has developed a system that uses cell phones as anonymous "traffic probes." Its first customer will be the Virginia Department of Transportation, which will use it in Norfolk this summer, said company president and chief executive officer Cy Smith. Neil Schuster, president of the not-for-profit Intelligent Transportation Society of America, said the auto industry is looking closely at federally dedicated spectrum space that could host a wireless network for moving cars.