Maryland transit officials likely will be able to fit a 5-foot-wide sidewalk next to the Purple Line tracks in part of the tunnel under Wisconsin Avenue in Bethesda, state Purple Line Project Manager Mike Madden said.
The sidewalk would allow users of the Capital Crescent Trail, a popular path for joggers and bikers that runs from Silver Spring to Georgetown, to continue avoiding traffic on the busy road by traveling underground after the 16-mile Purple Line light rail takes over the space the trail currently occupies inside the tunnel.
However, the sidewalk would not run inside the entire tunnel, Madden said. It would be on the north side beneath the Air Rights Building, but because of insufficient room beneath the Apex Building, trail users would need to go through the planned Purple Line and Metrorail platforms to leave on the other side.
"It would provide access for people into the station," Madden said. "It would not be a trail for people to ride their bikes on."
Madden emphasized that the sidewalk might not be possible. The Maryland Transit Administration is still working out some safety issues such as whether there is enough ventilation for people to walk alongside the trains, he said.
If the MTA determines the sidewalk is possible, Montgomery County would decide whether to build it and would be responsible for paying for it, Madden said. Construction on the sidewalk would begin with construction on the Purple Line platform and the tracks inside the tunnel in 2015.
"It's a reasonable option," said County Councilman George Leventhal, D-at large, a vocal Purple Line advocate. "Not perfect, but reasonable."
The Apex Building likely will be rebuilt in the next decade, he added, at which point the county may be able to build a better trail inside the tunnel.
However, advocates for the Capital Crescent Trail say they will not be satisfied with anything less than the full, 12-foot-wide trail in the tunnel.
"You've got people with strollers. You've got bicyclists," said Ajay Bhatt, president of the Friends of the Capital Crescent Trail. "Consider all the additional development that they're talking about in Bethesda. They don't expect more people to want to get across Wisconsin to enjoy the trail?"
The trail is used by more than 23,000 residents each week, according to a survey done six years ago by the Coalition for the Capital Crescent Trail.
Purple Line plans had included a new trail to run alongside the rail since 1990, but the County Council determined in the spring that it would be too costly.