The last weekend of track work in the Metro system in 2011 will cause single-tracking on all five lines.
WMATA says the most significant work will take place on the Red Line, where water main repairs will cause single-tracking between Dupont Circle and Judiciary Square.
Other single-tracking will occur in the following places:
-Orange Line trains will share a track between East Falls Church and West Falls Church
-Blue Line trains will single-track in two different spots: between Stadium-Armory and Addison Road-Seat Pleasant, and Reagan National Airport and Braddock Road.
-Yellow Line trains will also single-track between Reagan Airport and Braddock Road.
-Green Line trains will see minor service adjustments while trains share a track between College Park and Greenbelt.
All work will begin at 10 p.m. Friday and last through the end of service on Sunday. No track work is scheduled for the Christmas or New Year's holiday weekends.