Transit riders' favorite spring break is over: Metro is back at track work with an agonizing weekend of waiting lined up for riders.

The agency took four weekends off from its grueling track repair schedule during the National Cherry Blossom Festival. The agency is spending $5.5 billion to upgrade its system -- the largest capital improvement since Metro opened in the 1970s.

Metro will do work on all five lines and close three stations starting 10 p.m. Friday.

"Wow! They're really easing us back into it aren't they?" said rider Brian Calvary, using the Twitter handle @roadtohell.

Metro plans to do the following work on each line:

• On the Red Line, shuttle buses will replace trains between Gallery Place and Union Station. The Judiciary Square station will be closed all weekend as crews install brighter, more efficient lights between the tracks there. Metro said it needs to close the station for the work because the light fixtures are inches from the electric third rail. Riders should add about 10 to 15 minutes to their expected travel times. Trains will come every 10 minutes.

• On the Orange Line, Courthouse and Clarendon stations will be closed as crews replace a track circuit. Shuttle buses will replace trains between Virginia Square and Rosslyn, and riders using them should expect to spend an extra 15 minutes traveling. Trains will come every 15 minutes elsewhere on the line.

• On the Yellow and Blue lines, trains will share a single track between Braddock Road and Pentagon City. Trains will come every 30 minutes along the entire line. Metro spokesman Dan Stessel said the long wait time was necessary because of scheduling issues with other lines intersecting Yellow and Blue, as well as the long stretch of single-tracking between Braddock Road and Pentagon City, which spans four stations.

• On the Green Line, trains will single-track between Greenbelt and College Park. Between 7 a.m. and 9 p.m., every other train will begin or end at College Park instead of Greenbelt. Those traveling to or from Greenbelt should add 15 minutes.