A portion of the ceiling at Farragut North is under repair, though other parts are starting to look better. (Robert Thomson/The Washington Post)

Metro’s rebuilding program will affect service on four lines this weekend, but all the stations will be open.

Here’s the impact on rail service between 10 p.m. Friday and midnight Sunday.

Red Line. Crews will be working on ceiling tiles in stations and on the communications equipment. Through the weekend, trains will operate every 20 minutes from the ends of the line at Shady Grove and Glenmont. But additional trains will be in service from 9 a.m. to 9 p.m. Saturday and Sunday between Shady Grove and Farragut North and between Glenmont and Judiciary Square. In those two zones, which include most stations, trains should reach platforms every 10 minutes.

Orange Line. On Saturday, trains are scheduled to operate every 12 minutes (their regular weekend schedule) between Vienna and Stadium-Armory. Because there will be a work zone to the east of Stadium-Armory that includes the Minnesota Avenue and Deanwood stations, every other Orange Line train will operate between Vienna and Stadium-Armory only, so riders may have a longer wait at Minnesota Avenue, Deanwood, Cheverly, Landover and New Carrollton. On Sunday, Orange Line trains will operate every 20 minutes, rather than on the normal Sunday schedule of every 15 minutes.

Green Line. Crews will be working on the tracks between College Park and Fort Totten. Trains will operate every 20 minutes all along the line.

Yellow Line. There’s no work on the line this weekend, but because it shares tracks with part of the Green Line, where there is work, all the Yellow Line trains will terminate at Mount Vernon Square rather than at Fort Totten. A rider who wants to farther north would change to the Green Line, which arrives on the same side of the platform at Mount Vernon Square.

If you’re a longtime follower of these weekend track work announcements, you’ll notice that they’ve changed recently. The announcements used to talk about delays of so-and-so many minutes getting through the work zones where trains share one track. That was problematic for riders trying to plan trips and connections.

Metro has now spaced out the trains so that, as long as the schedule holds, there should be no delays getting through the single-tracking areas. By noon each Friday, this schedule should be incorporated into Metro’s online Trip Planner.