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Innovative design aims to alleviate traffic congestion in Haymarket

VDOT expects work to begin in a couple of weeks to reconstruct the conventional crossing of on and off ramps with an innovative design -- a diverging diamond interchange. (Courtesy VDOT)

WASHINGTON — When it comes to traffic jams, the Capital Beltway, Interstate 66 and Interstate 395 get a lot of the attention, but there are traffic headaches all around the Washington region, even in the growing Prince William County town of Haymarket, Virginia.

Congestion builds each morning and evening at the intersection of I-66 and U.S. 15, but transportation planners promise that help is on the way.

The Virginia Department of Transportation expects work to begin in a couple of weeks to reconstruct the conventional crossing of on and off ramps with an innovative design — a diverging diamond interchange.

“A diverging diamond does a couple of things: It helps allow more left-hand turns onto the interstate freely without opposing traffic; it reduces the number of conflict points where vehicles could collide with one another,” says Christiana Briganti-Dunn, design/build project manager with VDOT.

Sharp population growth along U.S. 15 in the past decade has produced daily traffic jams as streams of motorists line up for left turns onto I-66. It’s time-consuming, and left-turning vehicles at intersections with heavy traffic raise the risk of crashes.

“I’ve seen more accidents trying to turn left to get on 66 to go eastbound than you can shake a stick at,” says Robert Hall, a resident of Haymarket who turned out at a Wednesday night public meeting in which VDOT planners explained the project.

“The benefit of a DDI, or diverging diamond, is that those vehicles will all be either merging or diverging but generally are following in the same paths, next to one another, so they’re not actually crossing each other’s paths,” Briganti-Dunn says.

A second bridge will be built to carry U.S. 15 over I-66 along with two crossover sections. The current bridge will be reconstructed to create the diverging diamond.

The project — the third diverging diamond interchange in Virginia — is expected to be completed in 2017.

Maryland’s first diverging diamond interchange, which opened three years ago, is at Md. 295 and Arundel Mills Boulevard in Anne Arundel County.

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