LOS ANGELES — To combat its infamous traffic, Los Angeles has built subways and light-rail lines. It has widened highways and added carpool, toll and bus-only lanes. But the roads have remained stubbornly clogged, creating a drag on commerce and the quality of life that has persisted here for generations.
Now, in the latest ambitious and costly assault on gridlock, Los Angeles has synchronized every one of its 4,500 traffic signals across 469 square miles — the first major metropolis in the world to do so, officials said — raising the almost fantastical prospect, in theory, of driving Western Avenue from the Hollywood Hills to the San Pedro waterfront without stopping once.
But with the number of cars on the road here continuing to rise (and almost 7 million commuters already on the road each day at rush hour in the metro area), even the system’s boosters admit that it may not be enough to prevent gridlock from growing worse.
The average time commuters waste in traffic has climbed since 2008, according to the Texas A&M Transportation Institute’s annual urban mobility report from 2012; the latest improvements may ultimately do little more than slow congestion, rather than reverse it.
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Built up over 30 years at a cost of $400 million and completed only several weeks ago, the Automated Traffic Surveillance and Control system, as it is officially known, offers Los Angeles one of the world’s most comprehensive systems for mitigating traffic.
The system uses magnetic sensors in the road that measure the flow of traffic, hundreds of cameras and a centralized computer system that makes constant adjustments to keep cars moving as smoothly as possible. The city’s Transportation Department says the average speed of traffic across the city is 16 percent faster under the system, with delays at major intersections down 12 percent.
Without sy.chronization, it takes an average of 20 minutes to drive five miles on Los Angeles streets; with synchronization, it has fallen to 17.2 minutes, the city says. And the average speed on the city’s streets is now 17.3 mph, up from 15 mph without synchronized lights.
Mayor Antonio Villaraigosa, who pledged to complete the system in his 2005 campaign, now presents it as a significant accomplishment as his two terms come to an end in June. He argued that the system would also cut carbon emissions by reducing the number of times cars stop and start.
“I am proud that we are the first big city in the world to synchronize all of our traffic signals,” Villaraigosa said in an email. “By synchronizing our traffic signals, we spend less time waiting, less time polluting.”
James E. Moore II, a professor of civil and environmental engineering at the University of Southern California, said it was “the first U.S. deployment” of such a sophisticated system.
But in the long term, Moore said, any traffic-synchronization system — no matter how technologically advanced or comprehensive — is unlikely to keep gridlock at bay.
“If we reduce average travel time in Los Angeles by 20 percent, then we will see more people traveling,” Moore said. “It’s money well spent, but part of the benefit is not speed.”
Seattle Department of Transportation (SDOT) synchronized many of its signals in the mid-2000s, and major crossings are linked to a control room on the 38th floor of downtown’s Seattle Municipal Tower. But the network is less extensive than Los Angeles’.
Second and Fourth Avenues are commonly timed to give drivers a succession of green lights. But the lights are predominantly of fixed duration. In Seattle the lengths are calibrated to allow time for crowds of pedestrians to cross, and it’s common for walkers and turning drivers to hinder each other.
At Mercer Street, which was just rebuilt as a two-way boulevard, SDOT intends to install a new adaptive signal system this year that will read the numbers of incoming cars, and adjust the length of green and red lights in real time, said signal operations manager Brian Kemper.
Studies will be done this year to look at adaptive signal improvements citywide, Seattle Mayor Mike McGinn announced in March.
Other cities have chased to keep up with Los Angeles. The Southern California metropolis has remained at the forefront, with a system that is not only more widespread but also faster and more autonomous than most others.
The magnetic sensors in the road at every intersection send real-time updates about the traffic flow through fiber-optic cables to a bunker beneath downtown Los Angeles, where Edward Yu runs the network. The computer system, which runs software the city itself developed, analyzes the data and automatically makes second-by-second adjustments, adapting to changing conditions and using a trove of past data to predict where traffic could snarl, all without human involvement.
Long Beach and Gilroy, Calif., have already adopted the Los Angeles software, and Washington — the only city in the country that had worse traffic congestion than Los Angeles last year, according to the Texas A&M report — has considered buying it as well, Yu said.
“One intersection affects the entire network, so our system is very dynamic, constantly responding to demands of traffic,” Yu said. “But it takes a lot of infrastructure to do what we do. Other cities have similar operations. Ours is just very comprehensive.”
In concert with toll and carpool lanes, as well as other initiatives like changeable signs warning of road closings, traffic-light synchronization saves $1.3 billion in fuel and time per year, according to David Schrank, co-author of the Texas A&M report.
When buses are running behind schedule, the network automatically extends green lights in bus-only lanes. (When buses are running on time, they have to endure red lights along with everyone else.) When roads are closed for special events, like the Oscars or a presidential visit, light patterns direct cars to other streets, though that does not always solve the problem. President Obama’s visit here in August 2010, for example, forced the closing of a major thoroughfare, unleashing gridlock on the entire west side of the city.
The magnetic sensors pick up most bicycles as well. Pedestrians are tougher to record, but they are also accounted for. Walk lights are extended automatically in some cases — outside Staples Center after Lakers games, or in Jewish neighborhoods on Saturdays — even if no one pushes the walk button.
Still, many residents have not yet noticed the city’s efforts to ease gridlock. Moore said that to really reduce road congestion, cities must start charging commuters to drive on the busiest corridors and freeways, which, controversially, began recently on one freeway in the area.
“Traffic really just defines your possibilities at any given time,” said Jeremy Fuller, 29, a graduate student at the University of California, Los Angeles, who was born and raised here. “I think it’s gotten worse since I was a kid. As the city continues to grow in population, and the infrastructure doesn’t grow, it’s just always going to get worse.”
Seattle Time transportation reporter Mike Lindblom contributed to this report.