Computer Puts L.A. Traffic Signals in Sync

Pushing a computer key in a traffic control center deep under City Hall, Los Angeles Mayor Tom Bradley on Wednesday officially switched on a $9.6-million synchronized traffic signal system designed to ease congestion on downtown streets.

The brief ceremonies added 212 signaled intersections to the Automated Traffic Surveillance and Control System, one of the most sophisticated, high-tech traffic management systems in the nation. Traffic sensors embedded in the streets monitor auto and truck movements and, through computer links, automatically regulate the signals to smooth traffic flows.

Originally designed by the city’s transportation engineers to prevent gridlock on the streets surrounding the Coliseum during the 1984 Los Angeles Summer Olympic Games, the system is being expanded and will include Hollywood, the west San Fernando Valley and other areas of the city. By 1991, it will cover 1,600 intersections. Full development, encompassing all 3,800 of the city’s signaled intersections, should be completed before the middle of the decade at a cost of $180 million, officials said.

The system--called AT-SAC--will automatically monitor the flow of the 400,000 vehicles that go in and out of the downtown area daily. When congestion begins to build, the central computer will begin adjusting the timing on intersection lights, leaving the green on longer where traffic flows are the heaviest.

Computer display screens in the command center give traffic controllers a visual display of the signal locations, with various colored lights and symbols warning when trouble is building. When the system is completed, video cameras also will give these operators a picture of what is happening. When a signal malfunctions or an intersection is jammed by a stall or an accident, emergency response crews will be dispatched.

An evaluation of the system around the Coliseum during the Olympics revealed the streets handled 15% more traffic without jamming up, said S.E. Rowe, city Transportation Department chief. “We expect the same downtown,” he said. The system will be operational only during weekdays and during special weekend events.

Work already is under way on additions to the system in Westwood and soon will begin at the west end of the Ventura Freeway to ease congestion during reconstruction of that freeway, Rowe said.