The Red Line will shut down four consecutive weekends in July and August between Grosvenor-Strathmore and Friendship Heights to allow for testing of a sealant that could help prevent some major Red Line delays like last Friday’s shutdowns.

WASHINGTON — The Red Line will shut down four consecutive weekends in July and August between Grosvenor-Strathmore and Friendship Heights to allow for testing of a sealant that could help prevent some major Red Line delays like last Friday’s shutdowns.

During the shutdowns, Metro will test a new tunnel sealant meant to limit the amount of water that seeps into the nine miles of Red Line tunnels in that stretch. The water issues have been a problem for decades. Among other issues, the leaks and added grime increase the risk of smoke incidents like arcing insulators.

The area getting the sealant is only 3 percent of the most troubled parts of the Red Line, so long-term fixes for other areas remain a long way off.

The trial will focus on a 2,000-foot stretch of the inbound track between Medical Center and Bethesda and the interlocking area near Medical Center.

Metro said that before 2011, the agency had given up on trying to even use a crossover outside Medical Center to move trains from one track to another because it required daily work to keep it clear of muck and grime.

On weeknights from July 10 through Aug. 11, Red Line trains will single-track between Friendship Heights and Medical Center.

The weekend shutdowns between Grosvenor and Friendship Heights will be:

Saturday, July 15 and Sunday, July 16

Saturday, July 22 and Sunday, July 23

Saturday, July 29 and Sunday, July 30

Saturday, Aug. 5 and Sunday, Aug. 6

While the tracks are closed, a Metro contractor will drill more than 500 holes in the tunnel ceiling so that a grout sealant can be injected just on the outer edge of the tunnel. The grout would slide down around the outside of the tunnel walls, “like the way chocolate syrup cascades down an ice cream sundae,” a Metro news release said.

The holes are then going to be filled in.

While this has worked in the mining industry, Metro said this is unique for a transit tunnel. Metro expects to have a better idea of whether this worked in the fall when water issues tend to pick up.

Metro canceled plans for a long-term fix for the area last year after determining it was too costly.