The Pedestrian Always Rings Twice

Photo by Virginia Lee HunterBOB BLACKMER MEETS ME IN THE HALLWAY OF THE C. Erwin Piper Technical Center on Ramirez Street, at the crumbling edge of downtown Los Angeles. The center is the massive concrete building of the city's Department of Transportation warehouse, as well as various other technical departments. The LAPD Air Services Division dispatches helicopters from the roof. If you remember the movie Blue Thunder, you know the place. Up the street is the new "marble castle" of the MTA, across the street a HazMat cleanup site.

"Welcome to our organized chaos," says Blackmer, a trim man with tidy gray hair in a button-down shirt who has graciously agreed to give me a tour of Los Angeles' Automated Traffic Surveillance and Control system, or ATSAC. His official title is senior signal systems adviser for the city's Department of Transportation, but a better title would be "traffic guru." (He is, after all, president of the Traffic Signal Association.) After 34 years of service, Blackmer plans to retire this year, at 56. But he's worried -- not because he doesn't have another job; like so many municipal employees, he already has two business cards. Blackmer's worried because traffic management is his baby. He wants to know who's going to keep it together.

"There are a lot of talented people here, but not from the old school, not people who know the system from the inside out," Blackmer says, holding a mobile radio in each hand as we walk down the linoleum corridor to the preparation shop, where the traffic-signal-controller street cabinets are tested and prepared for deployment. The street cabinets contain input devices for detectors buried in the street, and detectors for the pedestrian-crosswalk pushbuttons. They also house the output devices that control the street lights -- green, yellow, red -- and a conflict monitor that puts signals into flashing mode in emergencies. A history in the department is important, because part of Bob's job is to ensure that utility carriers don't cut ATSAC's fiber cables when they dig up the street. "There are only five of us who know where everything is buried," he says. "We get together each morning, over coffee, and review the Underground Service Alert tickets."

LOS ANGELES BEGAN BUILDING ITS ADVANCED traffic-management system in 1983 by laying cable and connecting the intersections surrounding the Coliseum in anticipation of the 1984 Olympic Games. With a B.S. in electrical engineering from Cal State Northridge and 34 years' experience working with PacBell and with L.A.'s departments of Water & Power and Transportation, Blackmer quickly became a key player. He remembers speaking with Mayor Tom Bradley about the traffic system. "Bob," the mayor asked, "is this going to work? No bullshit." The system did work. It has since grown dramatically with the installation of a state-of-the-art control center and a 50-mile circular network -- a 24-strand fiber optic OC 3 SONET ring.

The city has 6,400 miles of surface streets and 40,000 intersections. There are 4,300 intersections with traffic lights; 2,600 of those are on the ATSAC system through a series of 20 networked "hubs." Blackmer and I drive in a borrowed department car to a nearby hub on North Virgil Avenue, near its intersection with West Temple Street. When we pull to the curb, we are in front of Fire Station No. 6. Blackmer picked this location to set up the ATSAC multiplexing and networking equipment. "I like firemen," Blackmer says. "They have a better attitude than the police." As if on cue, a firefighter dressed in blues lights the barbecue next to Blackmer's outdoor equipment shelter, preparing to grill a chicken. "Maybe it came from a neighbor," Blackmer offers, recalling how chickens raised at the shack next door have sometimes wandered into the station house.

When there is a fire and Station No. 6 is responding, a firefighter hits a button inside the station house, and all the traffic lights in the four surrounding intersections to the south adjust to give the firefighters the right-of-way. Blackmer leads me down to the intersection and directs my attention up to a towering steel pole. On top is a camera watching the intersection. Carved into the asphalt street -- across all lanes, in each direction -- are round circles. Each circle contains three turns of wire that create inductive loops. When a car (or even a bicycle) goes over the unseen circle, the magnetic field is affected and the ATSAC central computer knows the volume of cars going by, the average speed of the traffic and the "occupancy" or wait time of the cars on the edge of the intersection.

The traffic signals at each participating intersection in Los Angeles have a "background cycle," meaning they have a set time lag between green lights. The typical cycle is 60 seconds. ATSAC implements, monitors and can manually override the background cycle in those 2,600 intersections depending on "progression" or traffic flow. At the busiest intersection in the city, Veteran Avenue and Wilshire Boulevard, with 8,000 cars passing in a typical noontime hour, that cycle needs regular adjustment. A wide intersection such as Glendale Boulevard and Alvarado Street, which has multiple "phases," or directions of traffic, and a busy pedestrian crosswalk, can have a background cycle as long as 210 seconds.