Dial "T" for Traffic

UC Berkeley students participate in the Mobile Century cell phone testing. Photo credit: Abby Cohn UC Berkeley students participate in the Mobile Century cell phone testing. (Photo by Abby Cohn.)Berkeley graduate student Kenneth Armijo was stuck in bumper-to-bumper congestion for hours on the Nimitz Freeway. Conditions couldn’t have been better for testing a new technology intended to give motorists real-time traffic information and help avoiding commuting snarls.

“It was a long day of driving, that’s for sure,” said Armijo, a 26-year-old mechanical engineering student who hit the road in a unique experiment exploring the use of GPS-equipped cell phones as traffic monitors. Nearly 150 UC Berkeley students, including many from the College of Engineering, were behind-the-wheel participants in last month’s “Mobile Century” test.

Navigating a fleet of 100 cars carrying the special mobile phones, the student drivers traveled up and down a 10-mile stretch of the busy East Bay interstate for more than seven hours. Supported by a grant from the California Department of Transportation, the road test was part of a joint project by UC Berkeley’s California Center for Innovative Transportation and the Nokia Research Center.

Speed and location readings were transmitted from the cell phones every three seconds. The information was sent to servers and displayed over the Internet. The result was a computerized map bristling with tiny flags for each car and its velocity, creating a detailed picture of actual traffic conditions.

“We can reconstruct the flow of cars, their speeds and congestion,” said Alexandre Bayen, a UC Berkeley assistant professor of civil and environmental engineering. Mobile phones of the future could alert motorists to traffic jams, and help them select alternate routes, delay a car trip or switch to public transportation, Bayen said.

That would signal a major improvement over current tracking systems, which rely on an expensive network of roadway sensors, radar and cameras, and are mostly limited to metropolitan areas. GPS-equipped phones already are being manufactured and are expected to become standard in the near future. Because cell phones are ubiquitous, “there’s no infrastructure cost,” said Dan Work, a CEE doctoral student involved in the project.

Shortly after the cars were deployed on the freeway, the monitoring system proved it was indeed working. At an outdoor command center in Union City, a display screen showed that northbound vehicles were slowing dramatically. “We captured a five-car accident,” Bayen said. “We captured it live time.”

Along with testing the accuracy and efficiency of the technology, the experiment addressed privacy concerns. Researchers said they protected the identity of cell phone users with such safeguards as stripping identifying data from the phone transmissions and using advanced encryption techniques. Owners of GPS-enabled phones ultimately would have the option of turning the GPS off.

Looking ahead, researchers hope to conduct a longer term experiment involving at least 1,000 vehicles.

In addition to a $250 stipend, last month’s test gave students a chance to participate in cutting-edge research and exposure to a significant public policy issue of privacy.

The project had special significance for Armijo, who is studying vehicular fuel cells. “We can come up with new alternative sources of energy,” he said. “But in the end, when these cars are sitting in gridlock traffic, they’re using energy, whether renewable or not.” Monitoring traffic with cell phones is “really going to be useful to a lot of people.”