Metro's ongoing $5.5 billion rebuilding effort will close four stations on the Orange Line this weekend, as well as force trains to share a single tracks on the Red, Blue and Yellow lines, starting at 10 p.m. Friday.

Here's where riders can expect delays this weekend:

• On the Orange Line, four stations will be closed, including Vienna, Dunn Loring, West Falls Church and East Falls church. Free shuttle buses will replace trains from Vienna to Ballston. Riders on express shuttles between Ballston and Vienna can expect to add about 25 minutes to their travel time, Metro officials said. Riders on local shuttles that make stops at every station can expect to add 40 minutes to their trips.

• On the Red Line, trains will share a single track in two stretches: between Grosvenor and Twinbrook, as well as between Rhode Island Avenue and Takoma. Metro officials say trains will arrive every 28 minutes along the line, though the agency will add more trains during daytime hours between Grosvenor and NoMa-Gallaudet, so that trains in the center of the line will come every 10 minutes.

• On the Blue and Yellow lines, trains will single-track between Pentagon City and Braddock Road, creating wait times of 30 minutes between trains along both lines.

• No track work is scheduled for the Green Line.