To hear Kartik Patel talk, one would never guess Los Angeles is famous for traffic jams. Patel, a civil engineer, has spent the past 11 of his 32 years managing traffic here. He takes pride in the flow. Traffic here is the most carefully orchestrated in the US. The central computer system, known affectionately by its operators as ATSAC, reads information from thousands of motion detectors and cameras hidden along city streets and then times the stoplights accordingly. Engineers fiddle with the controls to speed limousines down Sunset Boulevard, for the Academy Awards, or to ease traffic around Dodger Stadium. About 15 years ago, a City Council member grumbled about paying for the system, so engineers shut it down. Gridlock developed immediately. ‘‘No one times (the lights) better than we do, and no one moves as efficiently as we do,’’ Patel says proudly. ‘‘All this is happening, and most people don’t even know it’s happening. That’s the beauty of it.’’ The system has grown exponentially since it began as a demonstration project connecting 118 Los Angeles stoplights during the 1984 Olympics. Now ATSAC controls 3,200 of the 4,200 signalled intersections in the city. City officials plan to connect them all within three years. Video cameras mounted on buildings or perched on 45-foot poles beam images back to the ATSAC headquarters. Dark loops embedded in city streets read the speed of cars travelling over them and feed information to the central computer. When speeds are low, the computer automatically lengthens the green-light time and shortens the red.Street sensors also read information off transponders—black disks resembling ice hockey pucks—attached to city buses and ambulances. The computer tracks bus spacing and will change the lights to speed them along. Engineers can also program stoplights to maximise the number of green lights for drivers travelling at certain speeds. Patel brings up a graph showing the number of greens a driver travelling 40 mph will hit on one main drag in northern Los Angeles.But wait a minute—40 mph? Isn’t the speed limit there 35? ‘‘Yeah, well, some are set at the speed limit,’’ Patel says a bit sheepishly. ‘‘I try to set them five miles above because that’s what people drive.’’ Other cities have pieces of the system, but none combines all the capabilities of ATSAC. On a recent Saturday morning, 70,000 people arrived for a 5K run for breast cancer research in central Los Angeles. We watched the cars line up on one street and get directed by police away from another. This required hands-on management, both on the street and back at City Hall. Behind Patel, Christabelle Alacar, 26, sat facing an inner ring of computers. She looks about 15. Are all traffic engineers guiding drivers this young? Alacar laughed. ‘‘If you learn it right out of school, you can pick it up faster,’’ she said. Alacar listens on a walkie-talkie to the chatter of city employees who can be seen on the video screens moving cones. About every 10 minutes they radio to her. ‘‘Let’s favour Normandie at Jefferson,’’ one says. ‘‘Roger,’’ Alacar responds. Click, click, click. The light at Normandie Avenue and Jefferson Boulevard stays green longer for north-south traffic than for east-west. (Sonya Geis)
