Metro says it’s found a solution to its leaking tunnel problem in Bethesda that won’t require the long-term Red Line shutdown some had feared.
Metro officials will present their solution to near-constant leaking issues outside of the Medical Center station during Thursday’s WMATA Board meeting. The project will entail shutting down the Red Line at the Grosvenor, Medical Center and Bethesda stations for 14 weekends starting in the summer or fall of 2016.
After consultation, Metro decided to install a precast concrete archway in the crossover tunnel just outside the Medical Center station. Water leaking from the ground above has led to numerous examples of arcing insulators, which has meant numerous delays and single tracking periods.
Metro said one-third of all arcing insulators in its system happen in the tunnel between Medical Center and Friendship Heights, requiring $3-$4 million of maintenance a year.
The Bethesda and Medical Center stations opened in 1984. A 2004 US Geological Service Report showed atmospheric pressure was responsible for driving water down through the tunnel and onto the track and track equipment below.
Metro said it originally considered a plan that would’ve meant closing the stations for five weeks, but sought other ideas because of disruption concerns.
To install the precast concrete archway, Metro will need the 14 weekends in 2016 — the last seven of which will have to be consecutive.
To make the best use of the weekend shutdowns, Metro also said it will do work on a number of other projects at the stations, including the new Purple Line entrance at the south end of the Bethesda station.
Metro will punch out the panels on the south side of the Bethesda station platform, add transformers, electrical cables, lighting, new fare gates, a kiosk and the elevators that will connect Purple Line riders to Metro’s Red Line at Elm Street and Wisconsin Avenue.
It will also install a retrofit device to make more sturdy the 21 concrete columns that hold up the elevated Red Line tracks just south of Grosvenor. That work will take eight to 10 weekends.
At Grosvenor, Metro will use the weekend shutdowns to replace tiles and rehab concrete along the station’s platform. Exposure to the elements, including snow, has caused concrete on the platform’s edges to deteriorate, in some cases falling to the track bed.
But the bulk of the work will happen underground, where Metro will be installing the archway, power washing the tunnel, injecting minor cracks, replacing rusted and damaged equipment and installing a drain pipe for heavy leaks. Metro estimated the total project will cost $12.2 million.
Photos via Metro