Wednesday, May 14, 2008

Increasing Fuel Efficiency through Synchronized Traffic Lights

The Texas Transportation Institute studies congestion in 85 urban cities across the U.S.

With all of the attention traffic congestion is receiving in Washington and other states, I'd be surprised if anyone disputes the Institute's latest report that congestion is increasing in both large and small urban areas.

What does increased congestion mean for the average commuter? In 2002, TTI estimated that increasing traffic congestion across America wasted fuel equal to 5.7 billion gallons - that's 75 gallons of gasoline per vehicle.

Byungkyu "Brian" Park, a University of Virginia researcher, announced that tweaking traffic lights to increase traffic efficiency can save fuel, reduces accidents and decreases harmful emissions into the atmosphere. Park’s computer model allows local governments to reset the timing of traffic lights so that cars and trucks flow through intersections more efficiently.

Unsynchronized traffic lights result in excessive engine idle time at intersections. According to, over 17% of your car’s gas is wasted by simply idling at traffic lights. One way to increase fuel efficiency in a town that does not synchronize traffic lights is to shut off your engine while waiting for the light to change.

When should you turn off your engine? Any time you are forced to sit idling for 10 seconds or more.

Traffic lights that are not synchronized result in lower fuel efficiency, increased automotive emissions and reduced worker productivity thanks to longer commute times.

Typically, traffic lights are operated on timers where each signal lasts for a certain amount of time regardless of whether there is approaching traffic or not. Other, more sophisticated traffic control systems use underground electronic sensor loops to detect waiting traffic. Sensors operate like metal detectors, so lighter vehicles like motorcycles, bicycles or other vehicles with low metal content often get missed by the sensors, forcing lighter vehicles and drivers to miss turn signals and green lights.

New technology allows lights to be controlled by computers so control devices can be coordinated with "real" traffic patterns.

Unsynchronized traffic light sensors, like those in Bellingham, slow traffic by detecting a lull and turn red just before cars arrive from the previous light. (I can think of dozens of examples in Bellingham).

Synchronized traffic lights can significantly improve traffic flow and relieves local and state government of the need to build new roads.

Some regions are turning off traffic lights when traffic is light. In this scenario, traffic in the main street may receive a flashing amber light to warn drivers that they are approaching an intersection. Traffic in secondary streets flash red. In Europe, many streets have yield and right of way signs to control traffic when signals are turned off.

Other strategies for saving fuel:

Don't race up to the stop light - allow your vehicle to coast to a stop slowly and accelerate evenly when the signal turns green.

Reduce braking - constant braking, cutting in and out of traffic and rapid acceleration burns more fuel.

Turn off the motor when you stop at a friends house, drop off a movie at the video store or stop to purchase coffee at your favorite coffee shop. (Drive through windows create excessive idle time).

Additional information on this topic can be found:

Lawmakers work to synchronize traffic lights:

Synchronization of traffic signals in Hawaii:

CA Proposition on Traffic Light Synchronization:

Texas Transportation Institute:

Other interesting topics for your consideration:

What's my vehicle's carbon footprint?

Longer Yellows reduce crashes:

Texas City caught manipulating yellow time for big $$ ticket profits:

Source documents for City manipulating yellow time for profits:

No comments:

Post a Comment