Last month, the city of Los Angeles achieved a major milestone: every one of its nearly 4,400 signalized intersections is now monitored and synchronized for more efficient traffic flow. L.A. is the first city in the world to do so, and the Automated Traffic Surveillance and Control System (ATSAC), which coordinates the effort, runs from inside a former bomb shelter four stories under City Hall East.
ATSAC's headquarters is a calm, quiet nerve center where a team of traffic engineers monitors more than a dozen screens showing live video feeds and animated graphics for every signalized intersection in the city. Engineer Edward Yu, who oversees ATSAC, says gathering traffic data from the roads requires three things, the first of which lies beneath the pavement.
"Loop detectors are the magnetic induction loops embedded in the ground. They're really the eyes that we use to see the traffic," Yu says. "As cars drive over them, they give us data about the speed, volume, and how long the cars have been sitting there."
The second component is cameras. Engineer Eric Zambon says there are more than 400 of them across the city - cameras that have pan, tilt and zoom capabilities mounted on 20 to 30-foot poles.
"Some of our cameras are mounted on high-rises, so that we can see multiple intersections and multiple directions," Zambon says. "We can get 15 or 20 traffic signals out of one camera."
Based on data from the loop detectors, a proprietary algorithm developed by ATSAC determines demand on a given intersection. Then, based on time of day or scheduled events like a Lakers game or the Academy Awards, it can modify a signal's timing in order to move traffic along.
Yu says it's all a balancing act. "We look at every intersection as a challenge, and we try to get it moving as efficiently as possible," he explains.
But has anyone noticed? Philippe Canton runs Dicarlo, a small wood-fired pizzeria at the point where Hillhurst, Sunset and Hollywood Boulevard converge. It's one of L.A.'s craziest intersections: major thoroughfares, each with their own left and right-turn arrows, pedestrian crossings and intricately orchestrated signal cycles that move traffic through a maze of 16 different lanes. Canton does his own deliveries -- sometimes up to 40 of them a day. Has he noticed traffic moving more smoothly?
"Two days ago I was going along Sunset, and for the first time, the traffic lights seemed to be synchronized," Canton says, "I thought it was just a coincidence, but apparently it's not."
But this is L.A. What happens if there's a water main break or a police chase? Engineer Quan Tranh says ATSAC's third component is human responsiveness.
"If we know a particular leg is closed off, we try to divert the traffic from there and use signal timing to change the pattern to re-route the traffic around the area."
Signal synchronization in the city began 30 years ago, in an attempt to improve the flow of cars on the streets in time for the 1984 Summer Olympics. What's different today is that so many more factors are in play: light rail crossings, bicycle lanes, school zones, even equestrians who cross traffic in certain parts of the city. In Jewish neighborhoods on Saturdays, for example, pedestrians who need a WALK light don't have to push a button.
"We recognize that during the Sabbath, they're unable to touch anything mechanical," explains Yu. This system moves them safely across the intersection without having to go against their faith.
A system this complex and adaptive is gently undermining the city's reputation for terrible traffic. Still, Yu says, there's always something to improve.
"The city's always growing, it's always developing. We're looking at ways to improve our existing system, upgrading our system, expanding it, using our data to give more motorists information. It'll be a matter of time before we develop the next big thing."
ATSAC recently licensed its specialized software to the California communities of Gilroy and Long Beach, and hopes to sell it to Washington, D.C., as well. If traffic can be tamed in the City of Angels, it can probably happen almost anywhere.