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Montgomery planners seeks ways to keep trail inside tunnel when Purple Line is built

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The Montgomery County Planning Board asked Maryland transit officials Thursday to consider moving a Bethesda station for a future Purple Line to try to better accommodate a popular biking and running trail in a tunnel beneath Wisconsin Avenue.

Board members said the state’s latest estimate that it would cost $40.5 million to rebuild the trail inside the tunnel would make it too expensive. However, they said they didn’t want to pursue a far less expensive plan to rebuild the trail along local streets through crowded downtown Bethesda unless they had exhausted other possibilities for keeping it in the tunnel.

The board asked the Maryland Transit Administration to report back to the county council on the costs, risks and impacts of two options for keeping the trail alone inside the tunnel beneath Wisconsin and two office buildings on either side.

One proposal would build the Bethesda light-rail station for the 16-mile Purple Line just east of the tunnel, perhaps using county land at Elm Street Park. Another would build it in the tunnel but east of Wisconsin, sparing the most problematic of the two office buildings on the western side. The state would have to buy and tear down the Air Rights building on the east side of Wisconsin but could recoup some of the cost by redeveloping the land, board members said.

Maryland transit planners have said they want to run street-level Purple Line trains in the tunnel to provide a direct connection, via elevators, to Bethesda’s Red Line Metrorail station below.

“This is a decision of real significance,” said Francoise Carrier, chairman of the Planning Board. “Representations have been made about how the trail would be treated, and now it turns out to be very difficult and expensive.”

County officials have long said they intended for the trail — the Georgetown Branch extension of the Capital Crescent Trail — to be rebuilt inside the tunnel as part of the state’s $1.93 billion Purple Line project. The trail’s costs would be the county’s responsibility. Federal transit officials considering the light-rail project for federal funding recently approved it for preliminary engineering.

MTA officials told the county last month that, upon more detailed engineering, they had discovered that keeping the trail in the tight confines of the tunnel would cause the trail costs to jump from an estimated $65 million to about $100 million, with 40 percent of the four-mile trail’s total cost stemming from the portion inside the 1,000-foot tunnel. Rebuilding the trail inside the tunnel would require significant excavation around 35 columns and other critical beams supporting the Apex office building on the west side of Wisconsin. Trail users would be enclosed in an eight-foot-high clear tube above the trains to protect them from the trains’ overhead power lines.

If moving the Bethesda station proves too costly or difficult, board members said, a county work group should study ways to protect walkers and cyclists if the trail must be rerouted onto local streets. One proposal includes timing the traffic signal at Wisconsin and Bethesda avenues to favor trail users, a change that could further delay traffic there.

Local residents and trail advocates unanimously told the board that they wanted the county to keep the trail inside the tunnel, saying it would be unsafe to require thousands of runners and cyclists to use local streets and cross busy Wisconsin.

“The state and county have always known this would be an engineering feat of no small measure, and they knew it would be more expensive,” said Patricia Burda, a Town of Chevy Chase council member. Keeping the trail in the tunnel “has been a long-term commitment to the community,” she added.

The board rejected the idea of keeping the trail inside the tunnel by single-tracking trains there after state transit planners said that would make the light-rail line too slow and unreliable.

Board members also recommended that the county spend $1.9 million to build switchback ramps to carry runners and cyclists from the trail alongside a Purple Line down to the Rock Creek Trail. Maryland transit officials said they would study ways to spare more trees in building the trail connection.

The council’s transportation committee is to discuss the trail Dec. 5, and full council consideration is planned for January.

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