A corroded running rail. Image by WMATA used with permission.

Metro plans to close the Medical Center and Bethesda stations for four weekends starting July 15th for a tunnel waterproofing project. Trains will also single-track between Medical Center and Friendship Heights at nighttime for a month beginning 9pm every weekday between July 10 and August 11. If this project is successful, it could mean more closures but also, eventually, fewer leaks and a more reliable Red Line.

Last Friday, Metro suspended service between Dupont Circle/Woodley Park and Grosvenor/Medical Center during morning rush hour. Thousands were delayed and trains were crush-loaded. Trains ran as far apart as every 15 minutes during a time they were supposed to come between every four and eight minutes.

The issues were due to reports of arcing insulators, which is when electricity finds a shorter path to complete a circuit rather than staying contained to the third rail, which runs alongside the tracks to supply power to the trains.

Water leaking into the tunnels can bring in dirt and debris which exacerbates the issue; brake dust from trains can also accumulate in the more-humid environment and stick to the tracks, fasteners, insulators, and more. While we don’t know for sure that that’s what caused Friday’s problems, there’s a good chance.

Red Line stations have needed waterproofing for years

The Red Line between Grosvenor and Dupont Circle is notorious for water leaking into the tunnels. The issue has been known about for years; the United States Geological Survey even released a report in 2004 detailing the rockbed and what makes the tunnels ripe for water infiltration.

Water infiltration in the Red Line is a significant factor in the number of arcing insulator and other track fires that have occurred in the area. WMATA’s press release about the coming work notes that over two-thirds of all arcing insulators in the rail system occur between the nine-mile section of track connecting Grosvenor and Farragut North. In turn, these incidents cause single-tracking or service suspensions and can disrupt thousands of commuters’ travel, like what happened on Friday.

Metro suggested back in 2014 that it might close part of the line for 14 weekends to install a tunnel liner to direct water away from the tracks and 3rd rail. But that project was postponed indefinitely because the sole bid for the work that Metro received was more expensive than the agency had anticipated.

Metro wants to get this done, but it will mean station closures and slowdowns this summer

Metro’s press release says the agency will be closing a section of the Red Line for four consecutive weekends, starting July 15th. During those times, Medical Center and Bethesda will be closed, and bus bridges will be set up to shuttle passengers between the two.

Red Line trains will also single-track between Friendship Heights and Medical Center every weeknight from 9 pm to close beginning on Monday, July 10th until Friday, August 11th.

The waterproofing pilot that Metro is performing essentially consists of drilling hundreds of holes in the tunnel walls so that crews can coat on a rubber-like membrane on their outsides. Metro hopes this is more effective in keeping water out of the tunnels than their usual method of simply filling tunnel cracks from the inside with grout.

If the pilot is successful, Metro likely will have to schedule even more shutdowns and single-tracking events in the future to waterproof the entire tunnel between Grosvenor and Farragut North. We can only hope any additional pain now leads to long-term benefits of dry and clean tunnels.