Montgomery County Executive Marc Elrich (D) has asked the Maryland Transit Administration to explore whether the Purple Line could be single-tracked inside the Bethesda station to allow enough room for the county to rebuild the Capital Crescent Trail there.

Doing so would save millions when the county’s capital budget, used for everything from transportation projects to school construction, is particularly tight, Elrich said.

Under the current plan, the county would spend $54.9 million to rebuild the recreational trail beneath Wisconsin Avenue in a new tunnel that would run adjacent to the Purple Line station. The Purple Line is being built inside an existing tunnel that runs beneath Wisconsin and a new office building in the downtown Bethesda Row area, at the 16-mile line’s western terminus.

If the state rejects the idea of single-tracking the line inside the station, Elrich said, the county should postpone building a new trail tunnel until at least fiscal 2027, beyond the current six-year capital budget.

“It’s $50 million for a 900-foot tunnel,” Elrich said Tuesday. “We can’t even meet our basic capital needs with the money we have in the budget.”

The idea has drawn criticism from county planners, cycling advocates and some local officials who say single-tracking any part of the Purple Line would make it slower and less reliable.

Montgomery County Council member Andrew Friedson (D-District 1), whose district includes Bethesda, said the state rejected the idea of single-tracking part of the line 12 years ago, when Elrich first raised it as a possibility.

“If we do it wrong with the notion of saving a few bucks, we will have funded a broken trail and Purple Line, and we won’t be able to repair them,” Friedson said.

The tunnel and the section of trail east of it between Bethesda and downtown Silver Spring have been closed since Purple Line construction started in 2017. The trail will be rebuilt alongside the Purple Line tracks.

Friedson said the council’s transportation committee recently voted to retain the $54.9 million in the budget to keep a separate trail tunnel on schedule, but the full council won’t act on it until this spring.

The MTA did not respond to questions or a request for comment Tuesday. On Friday, Ray Feldmann, a state Purple Line spokesman, said in an email: “We have received County Executive Elrich’s request and will be responding to him directly.”

The Seventh State blog, which first reported Elrich’s proposal, said the MTA told county officials in 2009 that light-rail systems with a portion of single track have longer travel times, less frequent service and less flexibility.

Elrich said the MTA didn’t give him a reason when it previously rejected single-tracking the line between downtown Bethesda and Columbia Country Club in Chevy Chase — an idea that he and former Bethesda-area council member Roger Berliner raised as a way to potentially reduce the effects on homes in between.

The light-rail vehicles will need to make way for each other at the Bethesda station to change tracks as they head back east toward Silver Spring, Elrich said. A county consultant found that a light-rail vehicle would have enough time to drop off and pick up passengers in the station, then return to the crossover without delaying an arriving train, Elrich said.

If single-tracking in the station provided enough room to include the trail instead of having to build a new trail tunnel, Elrich said, “it would save $50 million and get people a decent-size path going through a tunnel.”

The fate of the popular cycling and running trail beneath six-lane Wisconsin in downtown Bethesda has long been one of the most contentious parts of the Purple Line project, which is under construction between Bethesda in Montgomery and New Carrollton in Prince George’s County.

The Purple Line initially was scheduled to begin carrying passengers in March 2022. However, most of the line’s construction stalled in September after the initial contractor quit amid disputes with the state over schedule delays and cost overruns. The previous contractor, which is being replaced, said construction was more than two years behind schedule.

Elrich proposed the trail changes as part of a recommendation to cut $168.7 million, about 5 percent, from the county’s six-year capital budget.

The Montgomery planning board staff called any delay in the trail’s construction “unacceptable.” The Washington Area Bicyclist Association asked the council to keep the funding to ensure that cyclists and walkers could continue to avoid having to cross Wisconsin when the trail reopens.

Elrich hadn’t included funding for the trail tunnel in his proposed budget last year, saying the project had grown too expensive after its cost estimate had more than doubled during detailed engineering. The council later added the money.

The county has committed $282 million to projects related to the Purple Line, including rebuilding the Capital Crescent Trail, building the Green Trail along Wayne Avenue in Silver Spring, and building a new southern entrance at the Bethesda Metro station to connect it with the aboveground Purple Line.

The county also is building a surface trail in downtown Bethesda that follows 47th Street at Elm Street Park, crosses Wisconsin at the light and proceeds along Bethesda Avenue before joining the rest of the trail across Woodmont Avenue. That trail is scheduled to be completed later this year.