A worker conducting Red Line leak mitigation Credit: Provided by Metro

Riders on the Red Line should expect service disruptions over the next two months as Metro expands a waterproofing project in a leaky tunnel segment in the Bethesda area.

The transit operator is scheduled Friday to begin single-tracking on weeknights and weekends, so it can install a new waterproof membrane, which will affect service in the tunnel between the Grosvenor and Friendship Heights stations.

To do the work, Metro will single track during weeknights and weekends:

  • between Medical Center and Grosvenor stations from Dec. 22 until Jan. 11
  • between Friendship Heights and Grosvenor from Jan. 13 to 21
  • between Friendship Heights and Medical Center from Jan. 29 through Feb. 15.

Metro is injecting a polymer-based material in holes along the tunnel using a method called curtain grouting. After it is injected, the waterproof material drips down the walls to coat the tunnel. Metro began testing the waterproofing method with small segments of the Red Line tunnel and is expanding it with the new work.

This segment of the Red Line tunnel has been prone to leaking because it was built before the use of the New Austrian Tunneling method, which was used on other portions of Metro’s network to waterproof its underground tunnels.

Below is the detailed schedule of service adjustments provided by Metro for the work period.

Red Line trains will single track: 

Medical Center – Grosvenor 
Weeknights (Mon-Thurs)
Dec. 26-28, Jan. 2-4, 8-11, from 9 p.m. through closing nightly
Dec. 22-24, from 6 p.m. Friday through closing Sunday
Dec. 29-31, from 9 p.m. Friday through 6 p.m. Sunday

Friendship Heights – Grosvenor 
Weeknights (Mon – Thurs)
Jan. 16-18, 22-25, from 9 p.m. through closing nightly
Jan. 13-15, from 7 a.m. Saturday through closing Monday
Jan. 20-21, from 7 a.m. Saturday through closing Sunday

Friendship Heights – Medical Center 
Weeknights (Mon-Thurs) 
Jan. 29-Feb. 1, 5-8 and 12-15, from 9 p.m. through closing nightly
Jan. 27-28, Feb. 3-4 and 10-11, from 7 a.m. Saturday through closing Sunday.