Computer Chips In to Curb Congestion

Woodland Hills homemaker Allison Aries was hoping to see green traffic lights in front of her Thursday as she hurried along busy Ventura Boulevard on a shopping errand.

In the basement of Los Angeles City Hall, 26 miles away, traffic engineer Kang Hu was hoping to see the same thing.

Hu was sitting before a king-sized computer screen that showed a map of nine of the boulevard’s intersections in Woodland Hills. Green arrows appeared on the screen when traffic was flowing smoothly.

But when a minor traffic jam developed near Shoup Avenue, a bright, flashing-red light appeared on the map. Simultaneously, the computer adjusted the timing of traffic signals, and motorists temporarily gained a few extra seconds to pass through the intersection.

With her trip down the boulevard, motorist Aries was welcomed to the world of Automated Traffic Surveillance and Control--a $7.2-million project aimed at relieving congestion along San Fernando Valley’s busiest street.

Hu and other city Department of Transportation officials have switched on computer-controlled signals at nine of the 189 intersections to be modernized between now and February.

The system, the first of its type in the United States, has attracted traffic experts from as far away as Singapore and Saudi Arabia. The computer originally was used to speed traffic around the Coliseum during the 1984 Olympics, and traffic engineers estimate it has cut travel time in the area by 13%and increased average speed by 15%. The system was expanded to downtown Los Angeles last year.

The 10-mile-long Ventura Boulevard link is the most ambitious expansion of the system so far. “Our grand plan is to eventually computerize all 3,800 of the city’s signalized intersections,” said Hu, the city’s chief traffic-signal engineer.

The state is paying about 80%of the cost of the Ventura Boulevard project. Caltrans hopes the system will reduce congestion on the boulevard caused by the Ventura Freeway improvement projects now under way.

Traffic is monitored by magnetic loops placed in the pavement near each intersection. The loops are connected to a refrigerator-sized control box connected by fiber-optic telephone cable to the computer.

The computer detects traffic tie-ups when the magnetic loops indicate that cars are not moving when the signal lights change. In a particularly serious traffic jam, engineers watching the congestion on their computer screens can override the computer and operate signals manually.

Janoyan said engineers will be monitoring the system at night when Ventura Freeway lanes are shut down for construction and traffic is squeezed onto Ventura Boulevard.

If the network fails, each intersection control box has a mini-computer inside that will operate the signals on a preset pattern, said Verej Janoyan, a Northridge resident and head of the city traffic-control room.

The computerization effort began at the western edge of the city at Valley Circle Boulevard last month. Installers are working their way east, intersection by intersection, at a cost of about $50,000 per intersection, Hu said.

Construction workers reached Winnetka Avenue on Thursday. Technicians Jesse Ramirez and Keith Helgren worked to hook the fiber-optic cable to the control box as a nearby bank thermometer registered 109 degrees.

Officials say the electronic curb-side control boxes are equipped with interior fans that keep their microprocessors humming in temperatures up to 150 degrees.

When complete, traffic experts say, the new system may signal the end of an older one. Officials do not know whether the computerized signals can be used with special RTD bus traffic-signal override equipment that was installed at 50 Ventura Boulevard intersections two years ago.

The special bus devices, known as emitters, hold boulevard signals on green to let approaching RTD buses pass. Flashing infrared strobe lights mounted next to bus destination signs trigger switches that hold the green light an extra five or 10 seconds. The flashes are invisible to the eye.

Hu said the city plans to evaluate the effectiveness of the $880,000 bus system later this year. If they appear helpful and do not interfere with the new computer system, the emitters will be retained, he said.

Bus driver Ron Valdes said Thursday the computers probably will be more helpful to RTD drivers than the old system has been.

“I don’t think the emitters are that effective at all,” Valdes said. “They don’t seem to make any difference when you come up to a light.”

He said motorists seem to agree.

“When the word got out we were using these, cars would hang around us like fish. Now they don’t.”