A suburb-to-suburb express bus service with routes along the Capital Beltway linking Maryland and Virginia is emerging in the region’s 2021 transit wish list.

The two states are studying potential transit options to connect their most populous counties and to reduce the number of vehicle trips over the American Legion Bridge, one of the nation’s worst traffic bottlenecks. The proposals would link the Tysons area in Fairfax County with Bethesda, Gaithersburg and Silver Spring in Montgomery County.

The study, part of a larger vision to relieve congestion in the corridor, follows a historic accord reached a year ago between Maryland and Virginia to rebuild and widen the span over the Potomac River within the decade. Some transit investments could be implemented before a new bridge is built, officials said.

The goal is to “figure out what transit improvements we could put in there that would help improve person throughput across the bridge,” said Jennifer Mitchell, director of the Virginia Department of Rail and Public Transportation (DRPT).

Transit operations would complement the expanded bridge and the addition of express toll lanes. Virginia, which already has an expansive network of toll lanes, is adding 2½ miles of its 495 Express Lanes north to the American Legion Bridge.

Maryland is planning to add toll lanes on its side of the Beltway and on Interstate 270. The new American Legion Bridge would include toll lanes in each direction, while other lanes would remain free.

“Having express lanes in place that could carry people in buses across the American Legion Bridge without getting stuck in traffic will make a big difference,” Mitchell said. “It really will offer more competitive travel times and a better option than sitting alone in your car.”

The study’s preliminary recommendations released Dec. 18 include eight potential bus routes connecting the Maryland Route 355 corridor and Tysons, which has become a magnet for jobs and shopping. Some routes could be implemented with the opening of the express lanes on the bridge, while others could follow.

About 235,000 vehicles cross the bridge daily, according to the Virginia Department of Rail and Public Transportation. That number is expected to increase to 280,000 by 2040.

Nearly two-thirds of that traffic originates in Maryland, said Ciara Williams, the study’s project manager with the Virginia DRPT.

A Bethesda-Tysons route during peak hours in both directions would make stops at Silver Line Metro stations and major job sites in Tysons, then travel on the Beltway to Maryland, where it would serve Red Line Metro stations and job centers such as the National Institutes of Health.

Other options under consideration include service in both directions from Bethesda to Reston and from Bethesda to Dunn Loring via Tysons — as well as peak direction service to Tysons from Germantown, Gaithersburg, Silver Spring and Frederick. A route connecting Frederick County to Arlington is also under consideration.

Planners looked at 31 potential routes before narrowing the list to eight, using an analysis of travel routes between the two states, Williams said.

Officials are also looking at how to increase carpool and vanpool programs, as well as the use of technologies to discourage solo driving. For example, Virginia officials say the implementation of a High Occupancy Toll lanes system, which gives carpooling vehicles free access to toll lanes, has proved effective.

Bus service between Virginia and Maryland across the bridge isn’t a new concept. Metro ran an express bus route from Tysons to Bethesda and Gaithersburg two decades ago. The weekday service, called SmartMover, ran during peak commuting times to serve growing suburban job centers in areas not convenient to the Metrorail system. It was also an experiment to test suburbanites’ willingness to make commutes by bus.

The route was canceled after failing to draw enough riders, but officials say they expect demand is higher now because of development on both sides of the Potomac.

In recent years, the region has seen its largest share of job growth in Northern Virginia, driving up workforce demands in areas such as Tysons and Loudoun County, according to data from the U.S. Bureau of Labor Statistics. That pattern has created a need for transit outside a Metro map largely oriented for travel from the suburbs to downtown Washington.

In a letter to Fairfax County Board of Supervisors Chairman Jeff C. McKay (D-At Large), Virginia Transportation Secretary Shannon Valentine said the state is committed to providing funding for transit along the corridor. The state already has identified a revenue source: the 495 Express Lanes extension.

“Funding generated from toll revenues will be invested for the benefit of the users of this corridor,” Valentine said in the Nov. 30 letter.

The environmental review of the express lanes project is expected in early 2021, and construction is expected to begin later in the year.

Maryland and Virginia are also in the midst of negotiations for the new bridge, which is expected to have four express toll lanes, in addition to eight free lanes. Tolls will be similar to those on Virginia’s express lanes, fluctuating based on congestion to keep traffic flowing.

Across the Potomac, Maryland is advancing a plan to rebuild and widen the bridge concurrently with plans to widen the rest of the Maryland portion of the Beltway and I-270, adding up to two toll lanes in each direction.

At a November public meeting, officials from both states said the transit study aims to come up with alternative options to driving, solutions they say would help address one of the nation’s most congested corridors. The study recommendations, they say, should maximize ridership, serve low-income and minority populations, and provide access to jobs.

Residents can comment on the study’s preliminary recommendations until Feb. 1 at the study’s website. A virtual public hearing will be held Jan. 12, when those registered will be able to comment.

After the public comment period, Virginia and Maryland will issue final recommendations and begin to seek funding. The study is expected to be complete in early 2021.

“These draft recommendations are vital to reducing significant traffic congestion and improving the quality of life for Marylanders and Virginians traveling across the Potomac River,” Maryland Department of Transportation Secretary Greg Slater said in a statement.