Do Synchronized Traffic Lights Really Solve Congestion Woes?

Los Angeles recently became the first metropolis to use fully synchronized traffic lights. Yet LA still ranks as the worst city in the country for traffic. Why?

If you’ve ever driven in LA during rush hour, you know it can take an hour to travel 5 miles (and even at noon, it’s no cakewalk). The city is well known for its traffic problem and has tried a laundry list of solutions — widening highways, building rail lines and subways, even implementing carpool and toll lanes — to no avail.

Then they tried something really ambitious.

In April of this year, Los Angeles became the first major city in the world to synchronize all of its 4,500 traffic lights. This effort to reduce congestion, pollution, and wasted time took 30 years and cost $400 million. Transportation experts estimate that implementing this new system across the country could reduce traffic congestion by up to 10 percent and air pollution up to 20 percent. It would also theoretically reduce accidents at intersections, the amount of money spent at the pump, average drive times, and, of course, drivers’ frustration levels.

So what is this magical congestion reduction system?

Traditional timing system vs. synchronized traffic lights

Traffic lights are traditionally controlled by roadside or centralized timers that tell the lights what time schedule they should be on given peak and non-peak traffic congestion hours. For example, the timer might tell the light, “Use Timing Schedule A between 6 a.m. and 9 a.m., and then Timing Schedule B until 4 p.m.”

These timers are supposed to be updated and adjusted by the state every 2 years to keep up with recent traffic survey info. This is especially important for busier intersections that might experience increased congestion from new homes or businesses in the area.

But a 2007 report card from the National Transportation Operations Coalition gave traffic departments nationwide an “F” for data collection and traffic monitoring, both of which are crucial to well-timed traffic lights. In fact, an estimated 75 percent of the country’s 300,000 traffic lights require timing improvements.

This probably isn’t news to you. We’ve all found ourselves in a long line of cars waiting to turn left, only to find that the arrow turns yellow after 10 seconds. These delays happen because the timing of the lights does not reflect actual traffic conditions. And even if the lights were maintained regularly, the traditional system still can’t account for possible delays due to accidents, bad weather, or construction.

Cue the new system: synchronized traffic lights.

In LA, the Automated Traffic Surveillance and Control system, as it’s officially known, uses hundreds of cameras and magnetic sensors to measure traffic flow. A centralized computer system makes constant, real-time adjustments to keep traffic moving as quickly as possible. The magnetic sensors in the road also pick up most bicycles — pedestrians are more difficult but still accounted for. This is all without human intervention (except for the person monitoring the underground computer system).

Early estimates boast a 16 percent increase in traffic speed, as well as a 12 percent reduction in delays at major LA intersections. And yet, in the same month that the new system was implemented, LA again claimed the number one rating for worst traffic in the country according to INRIX, an industry leader in creating systems that analyze traffic data.

How is that possible after implementing one of the most comprehensive, modern traffic control systems in the world? Let us try to explain.

A long-term solution or a short-term fix?

Although many traffic experts agree that LA’s money was well spent on the synchronization, some are skeptical that the new system will reduce congestion in the long run. Statistics indicated an initial reduction in congestion … until people realized that the city’s roadways were less awful and a new population of previously avoidant motorists took to the roads.

It’s like loosening your belt after a particularly large meal — while it creates more room for your burgeoning belly, the space is quickly filled because you can finally relax (or eat dessert). The same thing is happening with LA traffic. By reducing average travel times, synchronized traffic lights allow more people to travel. The benefit may not necessarily be speedier traffic, but rather a greater number of cars passing through during the same amount of time. The level of congestion may stay the same simply because there are more cars on the road.

This is not to negate the positive effects synchronized traffic lights have had in LA. There are still fewer accidents at major intersections and fewer emissions from the average vehicle. In fact, some sources suggest that the reason LA still has so much congestion is because the city’s recent economic improvement allows more people to live and work there.

And with almost 7 million motorists on LA metro’s roadways during rush hour each day, even the system’s supporters fear it might not be enough to prevent gridlock.

Synchronized traffic lights: a verdict?

Though LA is the first major city to synchronize all of its traffic lights, the concept isn’t new and has been successful in several U.S. cities.

Portland, Oregon, for example, installed carbon dioxide emissions monitors at their intersections before working to improve traffic flow. The monitors recorded lower-than-average pollution levels and enabled the city to claim federal credits for pollution reduction. They then sold those credits for $560,000 on the carbon offset market and used the money to pay for Portland’s intersection improvements. Success!

For major commuter cities like LA, however, the benefits aren’t as immediately clear. With a sprawling urban landscape and a population far greater than most U.S. cities, it’s hard to compare the successes of Portland to LA’s less fruitful attempts.

So, do synchronized traffic lights work in the way they were intended? The answer’s a definitive sometimes. In LA’s case, it may mean heading back to the drawing board to get to the root of their traffic problems.

Do you think there’s a solution for LA? And do you think your hometown could benefit from synchronized traffic lights? Join the discussion in the comment section below.

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4 Responses to “Do Synchronized Traffic Lights Really Solve Congestion Woes?”

  1. b mclaughlin
    November 4, 2013 #

    Nice article Megan…really enjoyed it. I lived back east … Illinois, Ohio and Virginia…they all had syncronized traffic lights… LA is slow to the punch.

  2. Garrett Christnacht
    November 6, 2013 #

    While the underlying goal of traffic light syncronization is to make it through as many successive lights as possible, we know the reality. I would favor timing lights so that drivers never miss consecutive lights. Thwould apply at interchanges and shopping centers, where you might miss one light, but never both. Nothing is as irksome as missing several consecutive lights in a row!

  3. Brandon
    November 7, 2013 #

    Yes, there is a solution that LA (and all other major cities) could adopt to virtually guarantee there wouldn't be traffic jams:

    Let the market decide how best to allocate the scarce resources of space for cars on the road.

    Singapore has virtually eliminated traffic jams since it instituted real-time congestion pricing. Wanna drive to the city center during morning "rush hour"? That'll cost you $15. Wanna drive to the suburbs at 3 am? That's free (or maybe $1).

    I don't get why this country so proud of its "free-market economy" refuses to use the "free-market economy" to solve this extraordinarily costly problem (economic, social, psychological, and environmental).

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