Fix those Traffic Lights to Reduce Congestion (And Emissions)
by Jeremy Elton Jacquot, Los Angeles on 05.16.08
Image courtesy of grendelkhan via flickr
You know the feeling: You're sitting in front of a traffic light for what seems like an eternity -- yet there's no cross traffic. And, as luck would have it, the light immediately reverts back to red after only allowing barely a handful of cars in front of you to pass. Surely, you wonder, there must be a better way of doing this?
Well, it turns out that you'd be right -- and that tweaking just a few controls on those accursed traffic signals would be enough to significantly reduce road congestion and air pollution -- by up to 10% and 20%, respectively. Furthermore, it would help drivers conserve fuel and cut the number of accidents at intersections, as McClatchy's Fred Greve reports in his excellent piece.
According to the National Transportation Operations Coalition, roughly 75% of the country's 300,000 traffic signals need timing adjustments or replacements. A lack of skilled engineers, political resistance and bureaucratic ineptitude, however, are preventing the necessary reforms from being implemented at the national level.
Only at the state- or city-level -- in California, Florida, Washington, Minnesota, Maryland, Georgia and Texas -- are efforts underway to streamline intersections and revamp traffic management. Unlike other countries, which have adopted adapted signal-timing systems, most cities in the U.S. continue to use outdated, ineffective centralized timers. While the latter operate by set intervals, changing lights, say, every 10 minutes during a specific time slot, adapted signal-timing systems monitor traffic conditions and flexibly adjust to optimize the flow -- even in the case of an accident, poor weather or construction.
Yet, because they're expensive and difficult to program, the adapted signal-timing systems have made few inroads in traffic departments here. Local politicians are often unwilling to invest the necessary capital or time to push these new technologies through; as a result, over 95% of traffic signals in the U.S. are still timer-driven.
Thank goodness some more progressive-minded communities have been willing to take a stab at reform, often to great success:
Among the most resourceful is Portland, Ore., which installed carbon dioxide emissions monitors at intersections before it improved their flow. The lower pollution that the monitors recorded enabled Portland to claim pollution-reduction credits that it sold for $560,000 on the carbon offset market. The money helped pay for Portland's intersection improvements.Lakewood, Colo., another community that closely tracked before-and-after conditions, found that synchronizing lights at just 16 of its intersections delivered huge benefits. They included a daily savings of 635 hours in driving time, 172 gallons of gas and 758 pounds of pollution emissions, according to Denver's regional traffic authority.
Richard Plastino, Lakewood's director of public works, described the gains from improved intersections as "one of the few low-cost alternatives...to physical reconstruction of intersections and streets."
Then there's the real-life gain. Seattle, for example, retimed and synchronized more than 500 intersections between 1998 and 2002. The clearest result was a 20 percent drop in congestion on three of the city's major arteries.
As then-Seattle Mayor Paul Schell, the effort's leading proponent, argued at the time: "It's the one investment we can make in the near term that will make a difference in people's lives every day."
Los Angeles, anyone?
Via ::McClatchy News: There is something that can be done about the traffic (news website)
See also: ::Revisiting the Los Angeles Congestion Pricing Plan: Good Idea After All?, ::Bloomberg Congestion Fee a No-Go
My county just got $88,000 from the DOT to put these lights in, which is wonderful. Most of the traffic is on surface streets that get horribly backed up during rush hour because of stupid, stupid light cycles.
There's one pair of lights, less than 100 yards apart, that alternate red and green so that you sit for three minutes with no traffic crossing, pull forward 100 yards, and then sit for another 3 minutes. That is, unless you're the first car in line and floor it to squeak by in the yellow.
The Kansas City metro area currently has an initiative called Operation Greenlight:
http://www.marc.org/transportation/ogl/
I'm very pleased; it's not often I get to our report our city among the "more progressive-minded communities" in the nation, but I know they're doing what they can. :-)
I think you mean "adaptive", not "adapted" signal systems.
Great idea though. I live in Portland and it seems like really well-timed systems are hit-and-miss across the city. But where it works, it works well.
How about using the better traffic lights like they have in some other countries? I saw one in china that was 2 square lights LEDs. Not only were they cheaper to make because it was designed for LEDs in a marix, but the yellow light is missing! They turned off the border lights gradually making it more difficult to see the green light and the animation of this also acted in place of the yellow light..
As the article points out there is a shortage of qualified workers. I work for the Wisconsind DOT and though not specifically with signals, I do look at roadway improvements. At any rate, many cities have only a few engineers and a couple techs. These couple of engineers are responsible for far too much work. Even our department only has a handful of signal engineers and they are responsible for the most populated counties in the state. Typically when new developments are proposed, signals within half of a mile on the state highway network will be coordinated.
The other problem is funding. Though these systems are much less expensive than tearing up the road and expanding it, they are still not cheap. It should be noted though that these improvements actually indirectly pay for themselves when looking at time/gas saved to the public. That said, this improvement generally offers the most bang per dollar invested and I wish there was more emphasis given to signal timing and systems.
Amen!
We can save energy and reduce congestion not only by retiming current traffic lights, but also by:
- replacing certain medium-volume traffic signals with roundabouts
- fixing interstates to remove weaving and other energy-wasting elements
- experimenting with other nonstandard signals, such as replacing restricted-left turn signals with flashing yellow left turn signals in off-peak hours
How amazingly obvious is this? And not just obvious, but easy! Talk about low-hanging fruit...I've been saying this for years, but the obvious constraints of money and resources do not bode well for any infrastructure improvements in this country (which is why we need a Democrat in office). These kinds of broad-based efficiency solutions are indicative of the kind of thinking that should permeate all new design and engineering decisions.
An additional benefit would be to reduce stress levels--nobody likes just sitting and waiting at a red light!
When studying to become a civil engineer, I took a course on geometric highway design. One of the interesting points that was presented was that more than one study had shown that, if a highway capacity is increased by a given amount (i.e. 2 lanes to 3 lanes, or 50% increase), demand on that highway will increase by the same amount or more within one year. In other words, efforts to ease highway congestion can actually increase it since they make it more inviting for people to move further from their work places.
Traffic signals on city streets are a very different story, but I wonder if there could be similar issues.
Sorry Shay in KC I have to disagree.
Kansas City's "operation Green Light" is a joke. Kansas city's idea of traffic control is to force everyone to stop at every traffic signal. The intersections where the "adaptive" signals are in place are far worse than the old "sensor - timer" signals that they have replaced. I commute through town early every morning and am forced to stop at a average of 78% of the traffic signals, with about 40% of those having no cross traffic whatsoever. I honestly believe that Kansas City spent the money for the camera controlled signals just so they could eventually start mailing out traffic tickets like St. Louis. I long for the old "timed" control systems. Just give me corridor and tell me how fast to drive.