From WMATA:
“Metro will perform critical work on the Green Line in December to improve safety and reliability. The work includes both station closures and single tracking. Customers are encouraged to plan ahead and allow additional travel time.
December 6-7: College Park, Greenbelt Station Closures
The Green Line will not operate between Hyattsville Crossing and Greenbelt from Saturday, Dec. 6, through Sunday, Dec. 7. Green Line trains will run every 10 minutes, with Local and Express shuttle buses replacing trains between Hyattsville Crossing and Greenbelt.
Crews will be renewing train signaling control rooms.
December 16-30: Single tracking between U Street and Georgia Av-Petworth
From 10 p.m. Tuesday, Dec. 16, through Tuesday, Dec. 30, the Green Line will single-track between U Street and Georgia Av-Petworth stations while crews complete track, communications, and lighting upgrades. All stations will remain open, with Green Line trains running every 16 minutes. Yellow Line trains will run every 8 minutes on both weekdays and weekends.
Metro scheduled this work during the holiday season, when ridership is typically lower, to minimize impacts on customers.
Crews will replace rail and fastening systems, renew communications and signal equipment, and restore lighting infrastructure.
For more information, visit the winter major construction page.
Next Steps: Yellow Line to Greenbelt
Once construction ends, the planned Yellow Line extension to Greenbelt will begin on Dec. 31. Half of the Yellow Line trains will operate between Huntington and Greenbelt, and the other half will operate between Huntington and Mt. Vernon Square.”