Technology vs. Gridlock: city officials are upgrading systems that help provide quick traffic fixes.

L.A. traffic might seem hopeless but miracles do happen every day.

Like being able to use a left turn arrow in the middle of an intersection jammed with cars.

Or a choreographed series of green lights that keep traffic moving on Ventura Boulevard, one of L.A.'s most clogged byways.

Or video cameras that can quickly spot double-parked cars on major thoroughfares.

With little fanfare, Los Angeles has been at or near the forefront of technological advances -- from street sensors to satellite positioning data that keeps traffic moving, or as close to moving as is possible with more than 30 million vehicle trips on any given day.

"We can get improvements in traffic flow in the range of 20 percent to 30 percent, just as much as adding another lane would, but at much, much cheaper cost," said Bob Huddy, senior transportation planner with the Southern California Association of Governments. "For the first time, computer technology now allows us to monitor traffic in real time and make instantaneous adjustments."

Before the advent of "intelligent transportation systems," the typical street lane could accommodate about 500 cars per hour. Now, with a combination of computing power and telecommunications, a street lane can take up to 700 cars per hour, Huddy said.

In the world of traffic control, that can be the difference between moving and getting stuck in near-gridlock.

"It comes down to the ability to squeeze more traffic through in a limited space," said David Schrank, a researcher at the Texas Transportation Institute at Texas A&M University, which publishes an annual ranking of the nation's most congested cities. "If L.A. didn't use every tool in the book to do this, the delays would be double or in some cases even triple what you're seeing now."

Sensors are key

At its core, the technology revolves around those ubiquitous sensors embedded in thousands of streets and intersections that tell centralized computers how fast traffic is moving. Signals are sent from the computers to adjust the timing of traffic light cycles.

The sensors have their share of drawbacks, such as not being able to detect bicycles or pedestrians and requiring considerable maintenance. But when they work the results can be noticeably helpful.

Take, for example, left-turn signals.

For years, they were primarily used at a select few intersections and the turns could only be made on the green arrow. In recent times, the city has installed a series of "permissive" left turn signals, where there's a short arrow at the beginning of a cycle followed by a full green light that allows turning when there are gaps in oncoming traffic. The turn signal is activated only after a certain number of cars line up in the turn pocket.

The installation of these signals has been stepped up under Mayor James Hahn as part of a program to improve traffic flow at particularly busy intersections throughout the city. So far, 50 intersections have been upgraded, with another 25 in the works.

Left-turn signals involve a careful balancing act. When a turn signal is used, it takes away time for traffic to flow through the intersection, thus causing that traffic to back up (including when the left turn lane on the other side does not have an arrow). That's why these signals only operate when there are enough cars backed up in the turn pocket to trigger the sensor.

"If you didn't have it set up this way, you would have to lengthen the whole signal cycle beyond the desired 90 seconds, which causes long delays for the through traffic," said Verej Janoyan, senior transportation engineer with the L.A. city Department of Transportation and chief operator of the city's Automated Traffic Surveillance and Control center.

L.A. traffic engineers have also used the ATSAC system to synchronize traffic signals so that a car going down a major street at 30 miles per hour can hit a string of green lights. This saves the driver time and it also reduces traffic congestion along these major arterial routes.

Traffic synchronization 

The technology behind these metal-detecting sensors has been around for 50 years, but L.A. was the first city to make widespread use of it in preparation for the 1984 Olympics. That's when L.A. set up its ATSAC that now covers 75 percent of the city's 4,200 signalized intersections.

Over the past 20 years, assembling this system has cost about $200 million. Initially, all the funding was at taxpayer expense; increasingly, though, developers are footing the bill as part of mitigation measures for their projects.

Developers of the Staples Center and the Hollywood & Highland project contributed toward the ATSAC system, as has developer Rick Caruso for his Grove shopping center. (While Caruso has put the money aside, L.A. transit officials have yet to complete the ATSAC upgrades around the Grove, which has prompted complaints from Caruso.)

"L.A. has by far the largest amount of instrumentation in place of any metropolitan area," said Provin Vara, professor of electrical engineering and computer science at the University of California, Berkeley and a researcher at Berkeley's Partners in Advanced Transit and Highway center. "They have an extremely good team that uses these instruments to control their signal system."

Until 1996, signals could only run on preprogrammed cycles, controlled through traffic boxes at the intersection. But starting in 1996, ATSAC engineers developed the ability to use the mainframe computer at the ATSAC center to override the pre-programming and make nearly instantaneous changes in the signal cycle based on traffic conditions or an incident occurring at the intersection. That ability now applies to about one-fourth of the signals in the city and is being expanded as funding becomes available.

Roadbed sensors are being supplemented with digital video cameras that give traffic engineers at the ATSAC center far more data about what's happening on the streets. Cameras can reveal problems like double-parked cars or delivery trucks sticking out of alleyways. They can also see if a car is stalled in the middle of an intersection or if there is a collision.

"The sensor can tell you that you have a problem, that traffic is stuck somewhere. But with the camera, you can tell why you have the problem and then take steps to fix it," said Janoyan.

More cameras coming

Detecting incidents early on -- rather than waiting several minutes or even hours for someone on the scene to call -- can have a multiplier effect.

"If you take away one lane on a three-lane road, you don't just take away one-third capacity," Huddy said. "It's more like two-thirds capacity, since all those vehicles that would otherwise use that lane have to scramble to get into the next lane, screwing that one up, too. That's why so much emphasis has been put on getting these disruptions removed rapidly, with things like the freeway service patrol."

At present, roughly 200 of the 4,200 signalized intersections have cameras, but Janoyan said in the next few years cameras should be in place at most signalized intersections in the ATSAC system.

Road sensors and cameras are the most obvious examples of traffic-related technology, but there also are transponders on the new Rapid Buses using precise Global Positioning System data to determine when those buses should receive green signal priority.

The transponders mark the first time buses that have been integrated into the new traffic control technology. "We're now not just trying to move more vehicles quickly through city streets, we're also trying to carry more people," said James Okazaki, assistant general manager for the L.A. Department of Transportation.

In addition, message signs and radio traffic updates can be found near areas that host special events -- like the Staples Center -- or see huge volumes of traffic routinely, such as around Los Angeles International Airport.

"This is a strategy to tell people that there's congestion ahead; hopefully, they can try to find ways around those congestion points," said Okazaki.

But some say more can be done. The city of L.A., for example, does not make its congestion data available to traffic advisory networks that distribute those frequent freeway updates to radio and television stations.

"We have tried to establish a relationship with them (the L.A. Department of Transportation), but they have a policy that they don't want it to happen," said John Cox, president of Travel Advisory News Network in Diamond Bar.

Janoyan said the issue involves policy rather than technology.

"That particular company has a lot of advertising on its Web site," he said. "In that situation, an agreement must be crafted and approved by the City Council that ensures that there are no ads connected with the data that the city might disagree with."

Non-tech efforts

Of course, there's a host of traffic control measures that involves little or no technology. These fall into two camps: street improvements and persuading people to use alternative modes of transport.

Given how street widening is so costly, it's more common to see restriping, where lanes are narrowed to accommodate an extra lane. Traffic islands and speed bumps are also used to keep vehicles off of quiet neighborhood streets. And parking restrictions have become more common as a way to free up lanes during rush hour.

Most of these improvements have taken place around major developments and have been largely paid for by developers as mitigation.

The other strategy involves getting people out of their cars so that fewer vehicles dart about on city streets. Steps include requiring transit vouchers and vanpools, telecommuting and staggered work hours.

But getting people to abandon their vehicles in the car capital of the world is notoriously difficult. And widening roads or building new ones are even more difficult. Which is why most believe new technologies have to be a primary tool of traffic management.

"As long as most people work on a 9 to 5 schedule, there will be traffic congestion because so many people are trying to get to so many places at the same time," said Texas Transportation Institute's Schrank. "That leaves us with trying to find the best management techniques for the traffic we already have. And to do that, you need the full toolbox of technologies."

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Staff Reporter Michael Thuresson contributed to this article.