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Posted at 9:00 AM ET, 01/26/2011

Zigzag paint slows drivers at crossing

By Robert Thomson

Zig Zag markings.jpg

Workers painted zigzag lines in 2009 to slow drivers before this trail crossing. (Mike Salmon, VDOT)

Virginia transportation officials are pleased with the results of an experiment launched in 2009 to see whether drivers would slow for a trail crossing if they saw zigzagging white lines painted along the approach roads.

Safety engineers are always looking for ways to slow down traffic and protect walkers and bikers without endangering drivers. The question in this case was how to protect two points where the Washington & Old Dominion Trail crosses roadways in Loudoun County. Cars would be moving fast along Belmont Ridge Road and Sterling Boulevard.

The Virginia Department of Transportation looked at the situation and figured that simply posting signs that reduced the speed limit would not have the desired effect on traffic. Instead, they tried paint: Workers put zigzagging white lines down the middle of the lanes approaching the crossings. The idea was to create an eye-catching paint pattern that would alert drivers and slow them down.

Since the technique is unusual in the United States, this was a bit of a traffic science experiment as well as a traffic-calming technique. Virginia had to get permission from the U.S. Department of Transportation to set up the paint pattern, and the Virginia Transportation Research Council spent a year monitoring the results.

The study done by research scientist Lance E. Dougald found that the zigzags did heighten motorists' awareness and reduced their speeds. Drivers who responded to survey questions indicated that the new lines made them more likely to yield when they reached the trail crossing.

Most surprising to me was that the effect lasted.

"Before the study," Dougald said in a statement, "we thought the zigzag pavement markings would have an immediate impact on motorist awareness, but over time would lessen. It was interesting to see that the markings actually had a sustained positive impact on speed reduction even after the markings had been in place for one year.

"One possible explanation for this is that markings installed within the roadway, especially unique markings, are more visible than signage and are less likely to blend into the roadside environment."

Dougald's study recommended that VDOT continue maintain the pavement markings at the test locations while continuing to monitor the results for three years.The study also said VDOT should recommend to the Federal Highway Administration that zigzag pavement markings be included in the Manual on Uniform Traffic Control Devices for potential use nationwide.

See the full study in pdf format.

By Robert Thomson  | January 26, 2011; 9:00 AM ET
Categories:  Traffic Safety, Virginia  | Tags:  Dr. Gridlock, VDOT  
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Yet another reason why traffic in this area stinks. How about instead of finding more ways to slow down traffic, we find ways to separate drivers and pedestrians? A pedestrian bridge in each of these locations would make a lot more sense.

Posted by: gilmoredaniel | January 26, 2011 10:06 AM | Report abuse

gilmoredaniel, are you willing to pay more tax money to build a bridge? Those things are expensive (millions of dollars).

Dr. G., the Virginia Transportation Research Council has a new name. It is now the Virginia Center for Transportation Innovation and Research.

Posted by: thetan | January 26, 2011 12:06 PM | Report abuse

If VDOT starts painting these in lots of places, won't they just start to blend in as well?

Posted by: ah___ | January 26, 2011 12:28 PM | Report abuse

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