Crews set bulb-tee bridge girders over Difficult Run for the new westbound Route 7 bridge.
(Shirley Contracting photo)
People living in McLean, Va., and nearby communities are in an enviable situation. These upscale neighborhoods contain million-dollar homes, thriving job centers and the blue-ribbon schools of Fairfax County. But the residents also face some agonizing commutes along Route 7 in northern Virginia.
This busy thoroughfare is part of a corridor that runs from Leesburg to Tyson's Corner, a bustling center of shopping and jobs. Along the way, Route 7 connects communities in two counties to fire stations, a mega church, seven other churches, a mosque, schools, government contractors and nearly unlimited shopping and restaurant destinations.
In 2019, Virginia Department of Transportation (VDOT) began construction on a 7-mi. stretch of Route 7 to add an additional lane in each direction. The job is expected to be completed no later than July 31, 2024. The cost will be $314 million with Shirley Contracting as the lead contractor.
The task is a daunting one as Route 7 touches 36 homeowners associations. Cooperation has been the operative word as VDOT has held numerous public information, HOA and community meetings to gather local input.
Drivers experience severe bottlenecks during morning and evening commutes on this road, which has been a headache for travelers for some time. VDOT planners are looking to fix this corridor for travelers today and for the future. The road currently carries 52,000 vehicles per day with predictions for an increase to 86,000 by 2040.
Adding lanes to Route 7 is just one part of the complex project that will relieve congestion, improve safety and provide increased mobility for cyclists and pedestrians. In addition, project planners are coordinating with Washington Gas, which is making a $200 million upgrade to lines in the area.
Transportation Upgrades
The Route 7 project will touch the local communities in numerous ways beyond the expansion of the corridor from four lanes to six lanes. The list of improvements made by Shirley Contracting and subcontractors include:
- Building 14 mi. of continuous shared-use paths along eastbound and westbound Route 7;
- Adding a pedestrian underpass at Colvin Run Mill Park for enhanced park access;
- Lengthening left- and right-turn lanes from Route 7 to many side streets along the corridor and eliminating some median crossings for safety;
- Shifting Route 7 lanes away from Colvin Run Mill and enlarging a culvert under Carpers Farm Way;
- Replacing the existing Lewinsville Road intersection with a displaced left-turn intersection at McLean Bible Church;
- Widening Forestville Drive and Towlston Road to add southbound left- and right-turn lanes;
- Raising the Difficult Run bridges above flood elevation;
- Adding more than 7 mi. of noise walls with architectural treatment; and
- Adding a third left-turn lane from westbound Route 7 to southbound Baron Cameron Avenue, as well as a free-flow ramp from northbound Baron Cameron Avenue to eastbound Route 7.
Arif Rahman is VDOT's Design-Build Project Manager for the Route 7 Corridor Improvements Project.
"The Route 7 project is large and complex, but we decided to try to get it all done at once, rather than have to come back again soon with more disruptions," he said. "From the beginning of the job, we worked closely with people from the nearby neighborhoods so they could advise us about their interests and concerns. Then, we did our best to cooperate to see how we could address those concerns in the project."
Of course, the construction team had to maintain traffic on this busy thoroughfare during the many upgrades. The work has required more than 50 traffic shifts to accommodate the paving and construction. The work has required multiple crews working on various parts of the project at the same time.
The new lanes are 21.5 in. thick, with 6 in. of cement-stabilized subgrade, 6 in. of cement-treated aggregate and 9.5 in. of asphalt. Superior Paving of Gainesville produced the 306,000 tons of asphalt required for the project. The work also used 310,000 sq. yds. of soil cement and 230,000 tons of stone.
As with many of its projects, VDOT has allowed 32 to 35 percent of recycled asphalt pavements in the mix. The department has found through studies and observation that this amount of recycling saves costs, saves the environment and still provides quality pavements.
Challenges
The complexity of the project provided planners and construction teams with numerous challenges.
"We needed to sequence our construction so that we would not impact sensitive wetlands near a bridge area," said Rahman. "We also have done our best to make minimum impact to properties in the 36 homeowners associations we worked closely with. We worked carefully along easements that were outside of our construction zone. In some areas, we built sound walls on top of the retaining walls. In all, we built 7.2 miles of sounds walls to minimize the sound impact of traffic to the surrounding communities."
Other challenges included working around cemeteries and historic properties, including Colvin Run Mill Park. Built around 1811, the mill is the only operational 19th-century water-powered mill in the Washington, D.C., metropolitan area.
The project team constructed retention ponds to handle runoff and relocated the Colvin Run stream.
"When the team constructed the third lane on Route 7, we needed to relocate a 20-foot-wide stream," said Rahman. "We brought in about 40,000 square feet of concrete blocks to form a new straight channel for the stream."
This design minimized impacts to adjacent wetlands and park property while providing protection against future erosion of the stream banks.
Project designers incorporated an innovative intersection design of a "displaced left turn lane" at Lewinsville Road to help eliminate this chokepoint on the busy corridor. Intersections can be troublesome when vehicles, pedestrians and cyclists all intersect. A displaced left turn is a way to get more cars through a space than a conventional intersection would allow and to do it with fewer conflict points. This can increase the capacity of the intersection by as much as 70 percent. Signal coordination throughout the corridor also is enhanced. Raised islands also are utilized to channel the traffic and aid pedestrians crossing the traffic.
"We used the displaced left-turn concept in one other location in Virginia," said Rahman. "This is the second time it has been used in the state, and it looks like it will be very effective."
Shirley Contracting and its team used skid steers, excavators, dozers, pavers, rollers and cranes on the project. On several occasions, the construction team used innovative applications of Universal Total Stations (UTS) survey systems for the GPS guides. This has been found to help in increasingly exact applications of earth, rock and pavements.
In any project of this size and complexity, planners need to manage right-of-way land acquisitions.
"This area has a dense population, but we were still able to reduce easement impacts to adjacent parcels by 7.4 acres," said Rahman. "In my 20 years with VDOT, this is the most challenging and interesting project I have ever been a part of."
"We see the money NVTA has invested in the Route 7/Tysons corridor as well-spent, especially when it gets people home to their families faster," said Martin E. Nohe, former chairman of the Northern Virginia Transportation Authority, and Prince William County's former Coles district supervisor at the project's groundbreaking in 2019. "As our region's population and employment continues to grow, these types of improvements that provide alternate modes of travel for motorists, cyclists and pedestrians alike are critical to improving safety and reducing congestion." CEG
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