Are we doomed to sit in urban gridlock forever? If you go by our fast-growing auto fleet, it looks that way. Both people and cars are moving to the city—it’s anticipated that 70 percent of the world’s population will be urban by 2050, and everyone wants cars.

America alone has a quarter of the world’s cars on the road, 244 million. In 2011, the world topped one billion cars on the road for the first time. And that was only 24 years after we hit 500 million (1986) and 41 years after 250 million (1970). Eek, the cars are gaining on us.

Some places, like Shanghai, are addressing this by limiting the number of new car registrations. License plates there are worth more than $9,000 now, and fortunately there is no corruption or favoritism shown in the awarding of those plates….But there are other ideas worth considering, too. How about synchronizing the traffic lights?

Los Angeles has just completed the massive task of getting its 4,500 signals (across 469 square miles) to work in concert. The idea is that the lights work together, drivers will have smooth sailing. According to the New York Times, the Automated Traffic Surveillance and Control system took 30 years to build and cost $400 million.

Magnetic sensors in the roadbed are connected to a central computer, and traffic engineers studying screens can use that data to trip the lights at optimal times to avoid snarls. It used to take 20 minutes to drive five miles in LA; with synchronization that falls to 17.2 minutes (and the average speed of 15 mph is now 17.3 mph). The goal is 20 percent better traffic flow, and the city says it’s 16 percent faster now.

The LA system is probably the most comprehensive today, but it’s not the only one. In Pittsburgh, three foundations have worked with Carnegie Mellon University to create coordinated lights for the busy East Liberty part of the city. They’re claiming 40 percent reductions in vehicle wait times, 26 percent cuts in travel time, and 21 percent drops in emissions from idling cars. The best improvements were at mid-day, with 32 percent improvements in travel time, and a 52 percent reduction in the number of stops. The next step is expanding the pilot program, the city said last year.

“The idea is to optimize the movement of traffic through each intersection, and the results have been startling,” said Allen Biehler, executive director of Carnegie Mellon’s University Transportation Center.

They're also synchronizing lights in other cities, including Long Beach, California and the hugely jammed Washington, D.C. It's happening in Tulsa, Oklahoma, too, as this video attests:

Pittsburgh, by the way, also has the 6.8-mile Martin Luther King Jr. East Busway with 10 stations, and the West Busway (above). It’s not citywide, either, but it’s a cool idea. If buses, or light rail for that matter, is stuck in traffic it’s no better than driving. But dedicated busways, with their own corridors, can stick to arranged schedules—and get you there on time.

Obviously, there’s great opportunity for computers and software to unsnarl traffic. One place that’s happening is in Florida’s Miami-Dade County, where the city is working with IBM to reduce congestion and improve transit operation. At the simplest level, commuters can get access to traffic information, train and bus delays, stuff like that. Traffic engineers can get insight into historic patterns of congestion, too. But there are more advanced applications. Carmen Suarez, who’s in IT with Miami-Dade, told me that one way this is happening is a series of smartphone-accessed rewards for people who take the train downtown for, say, sports events.

“While you’re at the game and you’re hungry, your phone will say which restaurants in the area are participating, and what they’re offering,” Suarez said. “It might be free appetizers or two-for-one drinks. The coupons will be on the phone, and you can text the restaurant and tell them to hold your table.”

Traffic in Miami can be pretty awful, especially around Miami Beach. Those Miami Vice guys would be stuck in gridlock most of the time now. Miami-Dade County Mayor Carlos Giminez told me, “This is a quality-of-life issue, helping people have more time to spend with their kids. What we want to do is make it easier to use public transit, so people will know when the next train or bus is coming. We want applications that will have a return on investment, that will use our scarce tax dollars to the fullest extent possible. We want things that will knock people’s socks off.”

One possibility, Giminez said, would be apps that tell drivers how to find open parking spaces. The private Streetline app does exactly that, with sensors embedded in parking spaces. Again, LA is the lucky city to be the first wired. (There are 10,000 Streetline sensors in place there already.) Here's the video view from Miami and IBM:

Philly can get pretty snarled, too, and Dr. Daniel Lee, a University of Pennsylvania professor and a director of the federally funded UTC (run with Carnegie Mellon), told me that synchronized lights, also called adaptive signaling, can measure the number of people waiting in light at a red light and “make the green happen more quickly.”

Another thing UTC is working on in Philadelphia, Lee said, is monitoring bike lane effectiveness with cameras and cellphones, and making it safer for left-turning city buses to detect distracted cellphone-accessing pedestrians and, well, not hit them.

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

To cut L.A. traffic woes, city installs synchronized traffic lights
synchronized traffic lights in LA