A DIVERGING diamond interchange in Northern Virginia earned a project of the year award recently.
The project was honored by the Design-Build Institute of America, which also picked the project for a pair of other national awards in 2018.
The interchange is in the Haymarket area of Prince William County at Interstate 66 and U.S. 15. It opened in late 2017, and is the first diverging diamond interchange in Northern Virginia.
Who cares, right, it’s in Northern Virginia?
Well, it’s not the project’s location, but the design that matters.
The $149.4 million interchange project is being constructed along with the widening of Courthouse Road.
The original plans didn’t include a diverging diamond interchange. The new design emerged after funds were shifted from the project, which forced the Virginia Department of Transportation to adjust.
The result was the uncommon interchange concept.
The interchange design runs counter to instinct by crisscrossing traffic to the opposite side of the road through the intersection before traffic returns to the right side, or exits. Stoplights manage traffic flow, which is separated by medians and islands.
When the new design came about, the interchanges were still relatively unknown. So questions arose.
VDOT officials said the interchanges were proven and had a “smaller footprint” than the originally planned split diamond interchange. Officials also said the diverging diamond interchange manages traffic flow better, which will be key on Courthouse Road because it seems assured traffic will continue to increase there.
Diverging diamond interchanges originated in France in the 1970s, eventually immigrating to the U.S. in 2009, when the first one was built in Missouri, according to VDOT.
The first diverging diamond interchange in Virginia opened in 2014 in Louisa County’s Zion Crossroads, at Interstate 64 and U.S. 15.
That interchange seems to work just fine. And now we know the interchange in Prince William has a seal of approval.
Stafford’s diverging diamond interchange is expected to open for business by July 2020.
More closures of River Road in Stafford are on tap this week for work on the Belmont–Ferry Farm Trail. Work on an underground pipe closed the road several days last week.
The second closure, near the Pratt Park entrance, is slated for Tuesday through Thursday, from 9:30 a.m. to 3 p.m., according to an update from the county.
Pratt Park will still be accessible for traffic coming from U.S. 1. Those leaving Chatham Manor will be able to get to the Route 3 intersection.