To Fight Gridlock, Los Angeles Synchronizes Every Red Light
Los Angeles has synchronized all of its 4,500 traffic lights in an attempt to keep vehicles moving.
By Ian Lovett
The New York Times
April 1, 2013
LOS ANGELES — To combat its infamous traffic, Los Angeles has built subways and light rail lines. It has widened highways and added car pool, toll and bus-only lanes. But the roads have remained stubbornly clogged, creating a drag on commerce and the quality of life that has persisted here for generations.
Now, in the latest ambitious and costly assault on gridlock, Los Angeles has synchronized every one of its 4,500 traffic signals across 469 square miles — the first major metropolis in the world to do so, officials said — raising the almost fantastical prospect, in theory, of driving Western Avenue from the Hollywood Hills to the San Pedro waterfront without stopping once.
But with the number of cars on the road here continuing to rise (and almost seven million commuters already on the road each day during the rush in the metro area), even the system’s boosters admit that it may not be enough to prevent gridlock from growing worse.
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Built up over 30 years at a cost of $400 million and completed only several weeks ago, the Automated Traffic Surveillance and Control system, as it is officially known, offers Los Angeles one of the world’s most comprehensive systems for mitigating traffic.
The system uses magnetic sensors in the road that measure the flow of traffic, hundreds of cameras and a centralized computer system that makes constant adjustments to keep cars moving as smoothly as possible. The city’s Transportation Department says the average speed of traffic across the city is 16 percent faster under the system, with delays at major intersections down 12 percent.
Without synchronization, it takes an average of 20 minutes to drive five miles on Los Angeles streets; with synchronization, it has fallen to 17.2 minutes, the city says. And the average speed on the city’s streets is now 17.3 miles per hour, up from 15 m.p.h. without synchronized lights.
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James E. Moore II, a professor of civil and environmental engineering at the University of Southern California, said it was “the first U.S. deployment” of such a sophisticated system. But in the long term, he said, any traffic synchronization system — no matter how technologically advanced or comprehensive — is unlikely to keep gridlock at bay.
“If we reduce average travel time in Los Angeles by 20 percent, then we will see more people traveling,” Professor Moore said. “It’s money well spent, but part of the benefit is not speed, but throughput.”
The city started the traffic system in preparation for the 1984 Olympics at a handful of intersections surrounding the Los Angeles Memorial Coliseum, where crowds flocked to watch Carl Lewis and Evelyn Ashford.
Other cities have chased to keep up, adopting centralized control of at least some traffic signals. But Los Angeles has remained at the forefront, with a system that is not only more widespread, but also faster and more autonomous than most others.
Now, the magnetic sensors in the road at every intersection send real-time updates about the traffic flow through fiber-optic cables to a bunker beneath downtown Los Angeles, where Edward Yu runs the network. The computer system, which runs software the city itself developed, analyzes the data and automatically makes second-by-second adjustments, adapting to changing conditions and using a trove of past data to predict where traffic could snarl, all without human involvement.
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