Los Gatos Weekly-Times

Photograph by George Sakkestad

Video cameras at the intersection of Los Gatos Boulevard and Blossom Hill Road are helping control the movement of traffic.

Cameras, computers keep drivers moving

By Jeff Kearns

Big Brother isn't watching. Rather, the new cameras mounted on traffic light arms above the intersection of Los Gatos Boulevard and Blossom Hill Road are a high-tech traffic control solution that will cut maintenance costs while increasing traffic flow through one of the busiest intersections in town.

The video cameras replace older wire-loop detectors buried in the asphalt, which were torn up when the boulevard was recently resurfaced. Wire loops--which detect cars by measuring subtle variations in an electromagnetic current--tend to become unreliable as time passes and require costly replacement every few years, according to Chris Gjerde, associate civil engineer in the town's Engineering Department.

The new cameras, which feed into a computer that changes the signals by sensing changes in the graphic image of the traffic, are expected to go without maintenance or replacement for at least 15 years.

A computer by the roadside constantly calibrates itself as the image of the street changes with weather or time of day, so that it can distinguish between changes in light and a group of cars, says Mike Juha of Odetics, the Orange County-based company that first brought "Intelligent Transportation Systems" to market earlier this year.

Los Gatos even got a special half-price introductory offer on the system, which cost $11,000. According to Juha, wire loops need to be replaced every four to six years, at an average cost of $20,000.

The computer, which Juha says is roughly as fast as a 133MHz Pentium chip, detects changes in the graphic pattern of the street below which it recognizes as traffic, and signals another computer to change the signals accordingly. That computer, in turn, is supervised by yet another computer which checks--30 times a second--to make sure that traffic signals don't conflict and, say, turn all lights green at once.

The cameras are set up to see further down the road and can change lights as a car approaches the intersection, alleviating pollution from standing cars. Eventually, the intersection will be coordinated with other intersections so that when the lights let a large group of traffic pass through, the next signal down the road will know it's on the way.

While it may sound like a complex solution, Gjerde says the cameras should save the town thousands of dollars in the coming years. "You can detect cars better with the video cameras, and with a big intersection with lots of lanes, it's more economical to put them up. It's just a good way to save money and make things work better."

The intersection of Los Gatos Boulevard and Lark Avenue will also get a camera system early next year, courtesy of Caltrans, which will also use the cameras to monitor traffic as part of the Silicon Valley Smart Corridor Project.

Because Los Gatos doesn't have many other intersections as busy as Los Gatos Boulevard and Blossom Hill Road, the town doesn't plan to install additional camera systems, at least until prices start to drop.

The Los Gatos Police Department has no plans to use the cameras for enforcement, but the system could later be integrated into a photographic enforcement system, such as those used at some intersections in San Francisco.

The cameras don't have the resolution necessary to read a license plate, but Juha says that the video cameras could be connected to trigger another set of high-speed film-based cameras that could catch scofflaws--who would later find a ticket in their mailbox, along with a souvenir snapshot.

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