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Inside L.A.'s Automated Traffic System
See how Los Angeles' new system operates and why it means more green lights for drivers in one of the nation's most congested cities.
The city's transportation office is based inside 100 Main Street, the sleek new headquarters of the Caltrans regional office. (Photos by David Kidd)
The transportation department can monitor all city traffic from its operations center, located in the basement of a city hall annex.
The Automated Traffic Surveillance and Control system, or ATSAC, measures congestion at every traffic signal in the city.
The backbone of ATSAC is a series of thousands of magnetic sensors located just beneath the surface of the road.
Every traffic signal is accompanied by a metal locker containing the electronics that dictate its signal pattern. A city program allows local artists to decorate some of them.
Because of ATSAC, traffic signals operate more efficiently, which means more green lights for Angelenos.
Some buses are equipped with transponders that ensure they'll get an extended green light if they're running behind schedule.
Edward Yu, a senior traffic engineer with the city's Department of Transportation, oversees the operations of ATSAC.
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