One Metro source said the repair process—and the corresponding shutdown, if it is needed—could take a month and a half. "What we are going to do is we are looking to re-line the tunnels and that’s a significant effort," said Troup. Re-lining a tunnel is certainly not a quick process. A rubber lining is put in place around the tunnel and then a layer of concrete is installed around the lining. It’s not a project that can be completed in a weekend.Still, the deliberations over how to fix the fractured tunnel are only beginning, and Metro spokesman Philip Stewart says it could be at least another year before any repair plan is carried out. But if the transit authority goes ahead with closing a crowded three-station stretch, tens of thousands of daily riders will have to spend six weeks seeking alternate paths to work. Altogether, the Friendship Heights, Bethesda, and Medical Center stations take in about 26,500 passengers on an average weekday, according to Metro's recent ridership statistics. In a statement, Metro's deputy general manager, Rob Troup, says the seeping issue is not a safety concern but one of long-term reliability. But water and mud pouring onto the tracks from above could require a solution that puts out a lot of riders for an extended period, and that could definitely muck up the commute between DC and Bethesda. "Any decision around the appropriate long-term repairs, including timeline and possible effects on service, will be made only after final engineering designs are submitted in the coming months," Metro said in a statement.