For about five of the project's 22.5 miles, the trail would be squeezed between the highway and the concrete wall that will serve as a buffer between traffic noise and adjacent neighborhoods.
"It is air pollution, it's noise, small particles that get kicked up from the highway," said Bruce Wright, a member of the Fairfax Alliance for Better Bicycling. "Imagine riding on this trail and there is really no place to go if you have a problem. You are right next to a very tall soundwall, and you are right next to a jersey barrier."
Neighbors, meanwhile, don't want the trail on their side of the wall. Officials with the Virginia Department of Transportation acknowledge the plan isn't ideal but say it's an option that addresses the corridor's right-of-way constraints and the opposition from neighbors who refuse to have the trail on their side of the wall.
"Everybody is not getting the ideal situation," said Susan Shaw, director of Mega Projects for VDOT. "It is a compromise. We are trying to have an approach that balances those impacts and benefits and get the best project that we can."
According to VDOT's timetable, construction could begin this fall. The trail, along with four high-occupancy toll lanes — two in each direction — could open in summer 2022.
The project, from University Boulevard in Gainesville to the Capital Beltway, also will include three general-purpose lanes in each direction, new and expanded transit service, including additional park-and-ride lots, and median space reserved for future rail expansion.
Last fall, Virginia awarded the contract for the project to I-66 Express Mobility Partners, a consortium of Cintra, Meridiam, Ferrovial Agroman U.S. and Allan Myers. The consortium will finance, design, build and operate the toll lanes. In exchange, it will set and collect the tolls for 50 years.
As part of the project, VDOT also is expected to open HOT lanes on I-66 inside the Beltway in December, a much simpler effort because it involves setting up the tolling system without widening the highway.
The planned changes are aimed at reducing congestion while expanding travel choices. The I-66 corridor experiences eight to 10 hours of congestion daily, including weekends, carrying roughly 200,000 vehicles on an average day. With HOT lanes, tolls will rise or fall based on the level of traffic to maintain a consistent speed of 55 mph. The long-term solution, officials say, is to make it a multimodal corridor, with more transit choices and the addition of biking infrastructure.
"We are not trying to move more cars, we are trying to move more people," Shaw said.
The trail is a critical part of that effort, officials and bike advocates say. It would connect neighborhoods along the corridor to transportation hubs and the region's growing trail network, linking to the Custis Trail, which runs parallel to I-66 from the Key Bridge to the Beltway, and to the Washington & Old Dominion trail, a 45-mile path that extends from the Shirlington area of Arlington and passes through Falls Church, Reston and Herndon, all the way to rural Purcellville, in Loudoun County.
In intermittent segments between the Beltway and Route 28, the trail will be separated by a jersey barrier and a chain-link fence. The shoulder lane will provide an extra buffer from traffic, officials say.
Near the Vienna Metro station, the trail will go around the rail station rather than closer to the highway because building it immediately adjacent to I-66 would require moving the station's bus bays, which would be costly and disruptive to public transit users. Other stretches of the trail will be built along public green spaces.
As the design is finalized, planners are working to find alternatives, including areas where the trail can be elevated, officials said. Public hearings on the proposed design will be held this fall.
Biking advocates say they are most concerned about the five miles where bikers and walkers will be in direct proximity to 10 lanes of traffic. They are pleading with the state, and its private partners, to move the trail to the neighborhoods' side of the sound wall so that it is easily accessible from adjacent neighborhoods.
Critics also are concerned about the state's intention to use the trail for utility easements, which will put vehicles on the path with pedestrians and cyclists.
"Northern Virginia people really expect better," said Katie Harris, trail coalition coordinator for the Washington Area Bicyclist Association. "VDOT needs to design a facility that is safe and accessible and convenient for those who travel by bike. These are constituents of theirs that need to have their needs met as well."
Advocates say they understand neighbors' worries about having strangers in their back yards. At community meetings, residents said they fear a trail will bring crime, such as break-ins, to their neighborhoods. But that hasn't been the experience elsewhere in the region, biking enthusiasts said. Howard Albers, 69, a retired federal worker who lives just a short bike ride from the corridor, said a few adjustments to the plan would go a long way.
"It is not the best that it could be," said Albers, an avid rider.
"It will feel like you are riding inside of a canyon — a tall wall on one side and concrete jersey barriers on the other. Lots of concrete," he said. "If they could make just a few changes to their plans, it would be a much better experience for everyone and will have long-term benefits."