Cell Phones Could Act As `Traffic Reporters'

New Technology Aims To Track Flow

January 31, 2000|By Sam Diaz, San Jose Mercury News.

Your blood may boil when you see a driver with one hand on the wheel and the other holding a cell phone, but a California company hopes to convert all those radio waves into a traffic monitoring system that may actually improve your commute.

San Ramon-based U.S. Wireless is using its "RadioCamera" technology to track the physical movement of cell phones in a given area, based on the radio signals that transmit the user's voice to nearby cellular towers.

Those signals bounce off buildings and other obstacles, creating a pattern of reflections unique to the caller's location--a "fingerprint-like identity" for each spot in the mobile phone company's calling area, said spokesman Paul Brunato. When a mobile phone places a call, the RadioCamera technology matches the pattern of reflections against a database of the area's sonic fingerprints to determine the caller's location.

As the phone travels from one location to the next, the technology can calculate its speed and direction by tracking the changing sonic fingerprints. When lots of phones are tracked, a picture emerges showing where traffic is flowing--or slowing.

"What the system is doing is collecting the radio frequency energy being transmitted by all wireless phone users traveling on a roadway," Brunato said. "By collecting and identifying the locations of traveling vehicles, we're able to estimate velocity and congestion."

For traffic reporters, the technology will raise a red flag when cell phone movement is altered.

"Imagine looking at a map that shows cellular traffic moving at 65 m.p.h. on [Interstate] 280. You know there's no traffic there," Brunato said. "If it's moving at 5 m.p.h., you know there's congestion. If it's stopped, you know there's an incident."

The company, which is testing the accuracy of its technology in dense areas such as downtown Oakland, is building a database of the different signal path patterns in 100 U.S. metropolitan areas and is adding RadioCamera units to existing cellular towers in those areas.

It has already entered agreements with departments of transportation in Maryland and Virginia, as well as Traffic Station, a Los Angeles-based Internet traffic reporting agency.

Wireless phone companies are considering technologies like RadioCamera because of a safety-related federal requirement. By October 2001, these companies must be able to tell public-safety officials the approximate location of mobile-phone users who dial 911--an easy assignment for wired phones, but quite a challenge for wireless ones.

But U.S. Wireless is just one of a number of companies with competing ways to locate cellular callers. Other proposals would use multiple cellular towers to calculate a caller's position, or put location-sensing technology into the phones themselves.

Brunato says the RadioCamera system doesn't recognize the phone user for traffic management purposes.

"It has no idea of whose phone it is or the number," he said. "Compare it to a helicopter flying overhead monitoring traffic. It can see all the cars and how fast they're moving but has no idea who is driving that car. It just sees the traffic."