The Arlington County Board is one of the big reasons the 95 Express Lanes stop just north of the Capital Beltway rather than continuing up I-395 to the Potomac River. The board’s response to the original plan for the high-occupancy toll lanes was a lawsuit.

On Tuesday night, the 2016 version of the board voted 5-0 to give qualified support to the Virginia government’s plan to replace today’s High Occupancy Vehicle lanes in the middle of I-395 with HOT lanes, creating the northern extension of the HOT lanes.

What changed? The new plan, first presented by the Virginia Department of Transportation about one year ago, creates no new interchanges along the eight miles of the extension and has a limited effect on the existing ones. (The Eads Street interchange near the Pentagon will get some work to improve traffic flow, which it very much needs.) Another very important change in plan is to guarantee spending on programs that will let commuters leave their cars behind for trips in the I-395 corridor. Those programs haven’t been selected yet, but they’re likely to focus on carpooling, commuter bus trips and filling in gaps along biking and walking routes.

Both those factors are likely to lessen the traffic impact on county residents, but despite the board’s limited endorsement on Tuesday night, board members and community leaders along the I-395 corridor remain concerned and watchful.

Board member Jay Fisette, who introduced the supportive motion on the project, described the state of things:

“This is going to happen,” he said of the HOT lanes project. “It’s going to start construction next year.”

But his qualified support was based on the evolution of the plan: “When this proposal first came through, this was a very different project. This is a far better project.”

The process of developing the new project has been less confrontational and more cooperative. “There’s been collaboration between the state and the county,” Fisette said.

The board’s vote represents a significant change in thinking about the HOT lanes, but it wasn’t a legal hurdle the project had to overcome. The board wanted to get its resolution — both the supportive parts and the caveats — into the record as final decisions are made on the project. The state plans to begin construction in 2017 and open the express lanes in 2019.

The concerns voiced by board members and community leaders are natural on any big highway project that has a regional impact.

“Let’s be frank,” board member Christian Dorsey said. “The primary beneficiaries of all this are likely to live outside of Arlington,” a reference to long-distance commuters who travel from far suburbs to jobs at the Pentagon, Crystal City and the District — “whereas the primary impacts will be felt in Arlington.” People who live in the corridor are concerned about increases in traffic to and from the HOT lanes and the prospect of sound wall construction along the highway’s border.

“We just want to know that VDOT is on board to help us through it,” Dorsey said of the local concerns.

In consultation with their own transportation department, the board members amended the draft resolution that endorsed the concept of the HOT lanes extension. Among other things, the final resolution approved by the entire board asked that “VDOT move forward with an expanded traffic analysis to fully understand the impacts to arterial streets at signalized intersections at least one half mile beyond each interchange footprint, and commit to mitigation of those impacts in consultation with Arlington County.”

The HOT lanes project will convert the two HOV lanes of I-395 to three HOT lanes. Drivers who meet the HOV3 requirement can get a free ride in the HOT lanes if they have an E-ZPass Flex set to “HOV.” Other drivers will have to pay a toll collected electronically through a regular E-ZPass transponder. The toll will vary depending on traffic conditions. It’s the same tolling system drivers experience today on the 95 Express Lanes and the 495 Express Lanes on the Capital Beltway.