A rendering that depicts a Purple Line tunnel that would run beneath Bethesda. (Courtesy of Maryland Transit Administration)

Transit planners designing a future Purple Line say they have found a way to link a popular recreational trail with a tunnel beneath Wisconsin Avenue, overcoming a design hurdle for a light-rail station in downtown Bethesda.

A new sidewalk, five to seven feet wide, would connect the Capital Crescent Trail to a station that would be built inside the tunnel that cyclists and runners use today to cross under busy Wisconsin Avenue, state transit officials said Thursday. Trail users would have to walk through the station and across the platform between the two train tracks, planners told the Montgomery County Council’s transportation committee during a briefing.

Those who wanted to continue running or riding their bikes could avoid the station by using a new path that would require crossing Wisconsin at a traffic light. The Capital Crescent Trail runs east and west of the Bethesda Row shopping and restaurant district.

The idea drew praise from council members, who had rejected state plans to rebuild the 12-foot-wide trail through the tunnel in a concrete box structure above the trains’ overhead power lines. Doing so would have cost an estimated $50.9 million and entailed complex construction that would be risky for people in the two office buildings above the tunnel, planners said.

Council President Roger Berliner (D-Potomac-Bethesda) thanked Michael Madden, the Maryland Transit Administration’s manager on the Purple Line project, for finding a less expensive way to maintain trail access to the tunnel.

“This is a big deal,” Berliner said.

“This is teriffic,” council member Nancy Floreen (D-At Large) said.

A Bethesda station would be one of the busiest on the 16-mile transitway being planned between Bethesda and New Carrollton. It also would be a major transfer point for passengers connecting between a street-level Purple Line and Metrorail’s Red Line.

State officials have said they plan to start construction in 2015 and open the line in 2020, but the $1.93 billion project has no construction funding.

State engineers have cited the tight confines of the existing tunnel beneath Wisconsin, just east of the Landmark Bethesda Row Cinema, as one of the most challenging aspects of designing a Purple Line. Residents and trail users say public officials have long promised that they would keep the trail inside the tunnel if a Purple Line station was built there.

Ajay Bhatt, president of Friends of the Capital Crescent Trail, said he appreciated efforts to maintain a safe passage beneath busy Wisconsin but said a sidewalk would do little to offset the damage that a light-rail line would do.

“It’s 20 acres of park inside the Beltway,” Bhatt said of the trail. “You can’t replace that. . . . It will no longer be a park. It will be a bike path.”

Council member George L. Leventhal (D-At Large) said the state cannot afford to build the transitway without a gas tax increase.

“Many legislators have told me there won’t be a gas tax increase,” Leventhal said. “. . . If the transportation trust fund is not replenished, a Purple Line won’t happen.”