Metro customers can expect single tracking on the Red Line on weeknights and weekends over the next couple months, as the rail service expands its effort to waterproof tunnels.

Metro said that a pilot program to install a waterproof membrane in tunnels has shown some success, so it is moving forward with an eight-week effort to waterproof the Red Line’s deepest tunnel sections.

Here’s what Metro customers can expect in terms of service impacts:

December 22-24 - Single tracking between Medical Center and Grosvenor from 6 p.m. Friday to closing Sunday.

December 26-28 - Single tracking between Medical Center and Grosvenor from 9 p.m. through closing.

December 29-31 - Single tracking between Medical Center and Grosvenor from 9 p.m. Friday through 6 p.m. Sunday.

January 13-15 - Single tracking between Friendship Heights and Grosvenor from 7 a.m. Saturday through closing Monday. (Note: January 15 is the Martin Luther King Jr. holiday.)

January 16-18 - Single tracking between Friendship Heights and Grosvenor from 9 p.m. to closing.

January 20-21 - Single tracking between Friendship Heights and Grosvenor from 7 a.m. Saturday through closing Sunday.

January 22-25 - Single tracking between Friendship Heights and Grosvenor from 9 p.m. to closing nightly.

January 27-28 - Single tracking between Friendship Heights and Medical Center from 7 a.m. Saturday through closing Sunday.

January 29-February 1 - Single tracking between Friendship Heights and Medical Center from 9 p.m. to closing nightly.

February 3-4 - Single tracking between Friendship Heights and Medical Center from 7 a.m. Saturday through closing Sunday.

February 5-8 - Single tracking between Friendship Heights and Medical Center from 9 p.m. to closing nightly.

February 10-11 - Single tracking between Friendship Heights and Medical Center from 7 a.m. Saturday through closing Sunday.

February 12-15 - Single tracking between Friendship Heights and Medical Center from 9 p.m. to closing nightly.

Hundreds of Little Holes

Metro’s description of the waterproofing work is quite fascinating. In essence, workers are drilling hundreds of small holes into the tunnel ceiling and then injecting a polymer through the holes to form a protective layer.

Workers first tested this on a 2,000-foot section between Medical Center and Bethesda in July and were happy with the results. So, Metro expanded the pilot in October.

This waterproofing effort is design to prevent leaks onto the tracks and other Metro infrastructure, reducing the changes of corrosion, and ultimately making service more reliable.

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