Yahoo Autos Why Your City's Traffic Doctor Probably Can't Cure What Ails It
From the March 2016 issue
Steve Finton worked in storm-water treatment, then became the traffic-engineering manager for Torrance, California, one of the larger independently incorporated cities within greater Los Angeles. In general terms, Finton’s job is the same as before: Maximize flow through the pipes. If you live someplace of any significant size, there’s a Steve Finton on your payroll, no doubt also trying to push more load through the existing plumbing. I live about a mile from Finton’s office, and I’ve spent the past 11 years driving around Torrance wondering what witless car-hating commissar designed the traffic system. There seem to be no priority streets in our seaside grid, the commuters evoking quantum physics by racing from red light to red light in short bursts of quickly dissipated energy. Crenshaw Boulevard, a name synonymous with riots but a reality of modest commercial and residential tracts, limps from one red-hued thrombosis to the next until it finally reaches its southern terminus at a lovely little park overlooking the Catalina Channel—a park that is rarely visited because people expire of old age or brain explosion before reaching it.
Figuring that there were actual reasons it must be this way, I went to see Finton, a lanky bicycle enthusiast who nonetheless drives to work every day from neighboring Redondo Beach. He was sympathetic to my exasperation. “Everybody is a traffic engineer. We all drive the same roads; we all see the things that drive us crazy.” Facts hampering Finton’s efforts to make traffic move more smoothly: The Romans were long gone when L.A.’s city fathers decided to comb the ranchos into fine grids. There’s a good reason your body’s circulatory system is not a grid; it’s a recipe for flow constriction and blood clots. Sadly, nobody thought of traffic circles then (or, indeed, traffic).
Also, Finton, as with many local traffic engineers, doesn’t have full authority over his own grid. Three of the busiest thoroughfares in Torrance are state highways maintained by the state’s transportation agency. They cut right through the heart of the city, affecting the traffic flow on virtually every cross street. If Finton wants to change the signal timing of those streets, he has to jump into the gears of a whole separate bureaucracy.
This matters because traffic engineers start out with a basic time-versus-distance graph to plot signal timing. Finton drew a sample for me. On the vertical axis is time, on the horizontal axis, distance, with markers created by signaled intersections. In a perfect world, each “platoon,” or slug of cars released by a green light, should make an unimpeded 45-degree march across the chart, hitting each successive intersection just in time for the green. A signal’s cycle clock is divided into sectors. Thus, left-turners get so many seconds, cross traffic so many seconds, and so on. “All you want to do is clear the queue,” says Finton, meaning that nobody has to wait through two reds. Leftover green time, if any, goes to the busiest street. The clocks are constantly tweaked.
The problem, of course, is that the world is imperfect. The signals are not always evenly spaced, cross-street traffic is out of sync for some reason, the traffic is not evenly distributed, signal “sneakers” delay the platoon by shooting through under red, and pedestrian crosswalks can foul up the whole chart. Their use is unpredictable, and the national standard of four feet per second for pedestrians has dropped to 3.5 feet, acknowledging age and disabilities.
Then there are the intersections with those state highways. If I turn left from my Torrance-controlled street onto a state highway, I go from one light sequence to another and am likely out of phase until I can form up with a platoon. Then there are the cellphone users who go comatose at the wheel. Cellphone delay is so pervasive that Finton and his colleagues have considered adjusting the underlying assumptions about traffic behavior.
Smarter signaling, which began in the mid-1990s with the first computerized signal controllers, can now adjust for variations in traffic flow by sensing cars on inductive pads cut into the asphalt and also by “seeing” them with cameras. But they have to be reprogrammed manually. The city is moving to a new controller that can be remotely reprogrammed from a command center. But like every publicly funded infrastructure project, progress is slow. Finton has been working for years on a project to fix an intersection logjam with additional turn lanes. Much of the $18 million cost will go to relocating utilities and acquiring the property needed to widen the street. With road projects, nothing is ever quick or cheap.
Torrance packs 356 miles of streets and 119 traffic signals into 21 square miles. Like the rest of overcrowded Southern California, it is a city with arterial hypertension. Head in hand, Finton looks at the map and mutters, “Yeah, Crenshaw is a mess.” As the doctor, all he can do is try to make the patient a little more comfortable until something better comes along.
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