Metro won’t be doing any scheduled track maintenance on Sunday or Monday because of the Independence Day weekend celebrations, but the transit authority does plan to squeeze in some work on Friday night and Saturday in the District.

This will require trains to share tracks around work zones on the Red, Orange and Blue lines. It’s an unusual pattern for a weekend work schedule, and a little complicated.

Red Line: From 10 p.m. Friday through closing time, trains will share a track between New York Avenue and Rhode Island Avenue. Metro will be smoothing the rail surfaces and working on the bridge near Rhode Island Avenue.

From 7 a.m. to midnight Saturday, trains will share a track between Rhode Island Avenue and Fort Totten. From midnight until 3 a.m. Sunday, trains will share one track between Fort Totten and Takoma.

Riders should add about 20 minutes of travel time during these work hours.

Orange and Blue lines: Starting at 10 p.m. Friday and continuing all day Saturday till the 3 a.m. closing Sunday, trains will share a track between Eastern Market and Stadium-Armory. Workers will be replacing rail fasteners.

On Saturday, trains will leave the ends of the lines about every 20 minutes.

Many regulars know this, but since there will be plenty of tourists in town this weekend: The Trip Planner on the home page of Metro’s Web site is normally very helpful in scheduling rides. But it’s little computer brain can’t adjust for the weekend track maintenance, which throws off the schedules.