Weekday service will increase on the Metro’s Blue, Orange and Silver lines starting Monday, months after officials pulled most of its fleet in the wake of a train derailment.

Washington Metropolitan Area Transit Authority officials said Friday that the agency will add more trains to the three lines, which service the Foggy Bottom station, and trains will now arrive at least every 20 minutes on weekdays. On the weekend, officials said the Metro will aim to have 24-minute service on the Blue, Orange, and Silver lines, 20-minute service on the Green and Yellow lines and 12-minute service on the Red Line.

“We appreciate the patience of our customers,” WMATA CEO Paul Wiedefeld said in the release. “Our focus on making the legacy fleet available is allowing us to gradually add trains for passenger service, and I thank our workforce for their dedication and around-the-clock efforts to improve rail service.”

WMATA pulled 60 percent of its fleet in October after a train derailment revealed safety concerns on the Metro’s 7000-series trains. Delays have persisted since the derailment but have slowly improved as officials work to place older railcars back in service. WMATA announced last month that they would not place the 7000-series cars back into service until at least April as they focus on the root cause of the issue.

Metrorail has maintained more than 50 trains every day, including replacement trains used when railcars need “unexpected maintenance,” officials said.

“The increase of trains is sufficient to support more frequent, reliable service Monday through Friday for customers who continue to rely on Metrorail for work, travel and leisure activities throughout the region,” the release reads.