Light rain falls as traffic travels northbound on interstate 395 in Arlington, Va. (Matt McClain/The Washington Post)

T he expansion of Virginia’s extensive system of high­-occupancy toll (HOT) lanes is shifting to Interstate 395.

Construction is set to take off before the end of the year along an eight-mile stretch of Interstate 395, where today’s high-occupancy vehicle (HOV) lanes are being converted into toll lanes. The $480 million project will deliver the next major milestone in the state’s vision to create a network of more than 90 miles of HOT lanes in Northern Virginia by 2022.

About 45 miles of express lanes have opened on Interstates 495 and 95 within the past five years, and the state is set to open another 10 miles of HOT lanes on Interstate 66 next month.

“The goal is to move more people,” Virginia Deputy Transportation Secretary Nick Donohue said at a recent meeting about the Dec. 4 launch of the I-66 toll lanes.

By growing its network of toll lanes, officials say, the state will increase the capacity of its transportation network and give drivers more options. Solo drivers, for example, who cannot currently use the HOV lanes will be able to — if they are willing to pay. Having more people in the HOT lanes will help relieve congestion in the general lanes, officials say.

The benefit, officials say, is a quicker, more reliable trip than they could get using the interstate’s regular lanes. Drivers who carpool will be able to continue to travel free in the HOT lanes.

All HOT lane users will need a toll transponder. A portion of the revenue will help fund highway improvements and additional transit options.

The I-395 corridor spans 14 miles from the I-95/I-495 interchange and ends at New York Avenue NW in the District. The project covers only the Northern Virginia portion, which includes four northbound and four southbound general-purpose lanes, as well as two reversible HOV lanes in the middle.

Under the I-395 plan, those two reversible HOV lanes will be converted to three reversible HOT lanes without significantly affecting the overall width of the interstate. The HOV lanes operate in the northbound direction in the morning and southbound in the afternoon and night. HOV restrictions are in effect during the peak commute hours.

The lanes will change to a 24-hour toll system when the project is completed, officials say, creating an incentive for drivers who want to travel free to carpool.

Drivers in the area should expect to see construction activity pick up in the next few weeks as crews begin installing new sound walls. On-the-shoulder work will begin next year. The project also includes enhancements at the Eads Street interchange near the Pentagon to improve traffic flow.

Slated to open in fall 2019, the I-395 Express Lanes will essentially amount to an extension of the 95 Express Lanes. Those lanes stretch for 31 miles from Edsall Road in Alexandria to Garrisonville Road in Stafford County. The project will push the HOT lanes to the District line, from Turkey Cock Run near Edsall Road to the vicinity of Eads Street in Arlington.

Transurban, the company that operates the 95 and 495 HOT lanes, is overseeing construction and operation of the 395 lanes, under a contract with the state.

Replacing the HOV system on I-395 has been the state’s vision for more than a decade, but the plans were derailed for years, in part because of opposition from Arlington County.

Arlington came on board with the project in December 2015, but the county’s concerns have lingered. Some have questioned the state’s decision to use a third-party concessionaire to build and operate the toll lanes, and have urged the Virginia Department of Transportation (VDOT) to partner with the District to extend the express lanes across the Potomac River and improve transit, pedestrian and bicycle accessibility on the 14th Street Bridge.

Arlington officials say that the county will closely monitor any traffic impacts and construction noise. They also disagree over how much toll revenue will actually go to fund transit projects as promised.

State transportation officials anticipate $15 million in annual dedicated funding for transit. In a county document, Arlington officials said they found the “proposed annual transit allocation of $15 million to be insufficient to expand transit and other travel options in the corridor that will result in a meaningful impact on cost-effective non-auto travel in the corridor.” The county has asked Virginia to guarantee that a portion of any excess revenue received from the tolls will be used to fund additional transit projects.

The lanes will connect with the 31-mile network of reversible lanes on I-95 and with the 14 miles of HOT lanes on the Capital Beltway to the west. Nearby will be 10 miles of rush-hour, peak-direction toll lanes on I-66.

On I-66 outside the Beltway, construction is set to begin next year on a $2.3 billion expansion that will add toll lanes by 2022. That project spans 22.5 miles from the Beltway to University Boulevard in Gainesville, in Prince William County. On the southern end of the 95 Express Lanes, plans are to extend another 10 miles to Fredericksburg, also by 2022.

“If you are a commuter in Northern Virginia, every day is a challenge to find the best route to get to and from work,” VDOT Commissioner Charles Kilpatrick said. “We have done a number of capacity projects, but the realities are we have to continue to try to find ways of moving more people.”

Expanding the HOT lane system can be “a game-changer” for regional mobility, he said. The state estimates that the projects will help reduce congestion, provide additional travel choices for solo drivers and improve travel reliability. As with the other HOT systems, the toll will vary to control congestion and maintain an average speed of at least 45 mph. There is no cap on the toll pricing; the toll will increase as congestion rises and decrease as it lessens.

Officials say that toll revenue will provide a reliable source of funding for transportation projects.

“Transportation improvements are incredibly expensive,” Kilpatrick said. “The revenue generated will be used to operate the facility and to make improvements in the corridor.”