Fix those Traffic Lights to Reduce Congestion (And Emissions)


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 Unlike other countries, which have adopted adapted signal-timing systems, most cities in the U.S. continue to use outdated, ineffective centralized timers.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

Tags: Traffic

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