Maryland transportation planners analyzing how to add toll lanes to the Capital Beltway and Interstate 270 are “very much favoring” making the lanes free or lower cost for vehicles with three or more people, the state’s acting transportation chief said this week.

The high-occupancy toll (HOT) lanes would be designed to encourage carpooling and connect with HOT lanes on Virginia’s part of the Beltway, acting Maryland transportation secretary Greg Slater said.

In a briefing Tuesday before the House of Delegates’ Environment and Transportation Committee, Slater said the decision wasn’t final because the project is undergoing a federally required environmental impact study.

However, he said, “We’re very much favoring a high-occupancy toll solution that incentivizes carpooling.”

State officials’ previous refusal to publicly commit to HOT lanes has drawn criticism that the toll lane plan promoted by Maryland Gov. Larry Hogan (R) wouldn’t do enough to reduce the number of single motorists who add to traffic congestion. Critics also had raised concerns that the toll lanes would need to be seamless between Virginia and Maryland for motorists crossing the American Legion Bridge, which is slated to be replaced and expanded to include toll lanes.

Slater said Maryland plans to follow other states in requiring three or more people to be considered “high-occupancy,” or HOV-3. He said ride-hailing companies, such as Uber and Lyft, have greatly increased the number of vehicles with two people and aren’t “necessarily the spirit” of a carpool vehicle.

Virginia also has an HOV-3 requirement for vehicles to use express toll lanes free on the Beltway, I-95 and I-395.

Slater cited figures from Virginia showing that carpooling has continued to grow in Virginia’s toll lanes on the Beltway and I-95. Increasing carpooling, he said, would be a way to control traffic congestion as the region grows, in addition to investing in mass transit and building park-and-ride lots to connect motorists with commuter buses that would use the express lanes.

“They’re seeing a growth in carpooling because they’ve incentivized carpooling as part of their toll projects. So we’re hoping we’re going to see that as well,” Slater said.

Maryland’s Board of Public Works approved Hogan’s toll lane plan Jan. 8 as a public-private partnership, and the Maryland Department of Transportation has said it plans to begin soliciting companies in February. Under the state’s plan, teams of companies will build the lanes and pay for their construction in exchange for keeping most of the toll revenue over 50 years. The regular lanes, which will be rebuilt, will remain free.

Maryland transportation officials had previously agreed to allow public transit buses to use the toll lanes free.

Slater said the toll rates haven’t been set.