Signs tell Metro riders that the Crystal City Metro Station will be closed for six days in this July photo.
(Katherine Frey/The Washington Post)

The next surge of Metro’s SafeTrack maintenance program will start Feb. 11, with an 18-day shutdown between Rosslyn and Pentagon stations on the Blue Line, the agency announced Thursday.

Metro also will add an extra installment to its list of 15 scheduled maintenance surges, performing a 16th surge in June that will require continuous single-tracking between the Shady Grove and Twinbrook stations on the Red Line — the second time that Metro will focus their efforts on that stretch of tracks.

The updated schedule is a significant shift from the original plan laid out by the agency last year, when the last surge was expected to conclude in March, with only overnight and off-peak maintenance work continuing into the summer.

Since then, agency officials have modified the schedule several times and delayed some surges because of new information about the state of the tracks, as well as slow progress on the maintenance work because of weather.

Metro General Manager Paul J. Wiedefeld said Thursday that officials decided to institute an extra surge on the Red Line because “we found some issues there that need to be addressed,” though he did not specify what those issues were. Generally, SafeTrack work centers on repairing and replacing the most common problems on the tracks: deteriorated wooden rail ties, loose fasteners, outdated insulators and fraying power cables.

“One thing we’ve done differently, I think, is that when we find things, we deal with them,” Wiedefeld said. “We’re not pushing them off. As we’ve gotten out there and are finding more things, we’re dealing with them now.”

The stretch of the Red Line planned for the last surge, between Shady Grove and Twinbrook stations, underwent 13 days of single-tracking in August.

Metro spokesman Dan Stessel said the need for more extensive work on the northwest portion of the Red Line became apparent a Silver Line trained derailed just outside East Falls Church in July, when Metro inspectors and federal regulators realized there were significant issues throughout the system with track crossovers — the junctures where two sets of tracks cross over one another.

Stessel said it’s best to perform as much of the disruptive work as possible before the end of the fiscal year in June.

“Why not bang out this stuff while you still have the program in place?” he said. “Just get it done.”

SafeTrack surges were canceled for the month of January, because of preparations for Inauguration Day, as well as concerns about winter weather.

In Thursday’s announcement, the agency also revealed details on Surge #13 which consist of a month of single-tracking on alternating stretches of tracks between Braddock Road and Huntington and Van Dorn Street stations on the Yellow and Blue lines.

Metro also is planning for single-tracking on the Green Line between Greenbelt and College Park in April and May, and then single-tracking on the Orange Line from Minnesota Ave. to New Carrollton in May and June.

Here are the details on the updated  SafeTrack schedule:

Feb. 11 to Feb. 28, no trains between Rosslyn and Pentagon, Blue Line

– Blue Line trains will operate between Franconia-Springfield and Reagan National Airport

– Arlington Cemetery Station closed (served by buses from Pentagon)
March 4 to April 9, Braddock Road – Huntington/Van Dorn Street, Yellow and Blue lines

– Continuous single tracking will significantly reduce Yellow and Blue line service.

March 4 through March 26

– Continuous single tracking on the Blue and Yellow lines between Braddock Road and Huntington/Van Dorn Street.

– Blue Line trains will run every 24 minutes.

– Yellow Rush+ trains will not operate between Franconia-Springfield and Greenbelt.

– Yellow Line will operate in two segments:
Between Huntington and King St-Old Town every 12 minutes
Between Reagan National Airport and Mt Vernon Square every 6-12 minutes

– Between King St-Old Town and Reagan National Airport, only Blue Line trains will operate.

March 26 through April 2

– Continuous single tracking on the Blue Line only between King St-Old Town and Van Dorn Street.

– Blue Line trains will run every 24 minutes.

– Yellow Rush+ trains will not operate between Franconia-Springfield and Greenbelt.

April 3 through April 9

– Continuous single-tracking on the Yellow Line only between King Street-Old Town and Huntington.

– Yellow Line trains between Huntington and Mt Vernon Square/Fort Totten will operate every 24 minutes at all times.

– Blue Line and Yellow Rush+ service will operate normally.

Greenbelt – College Park, Green Line, April-May (Dates to be announced)

– Continuous single tracking on the Green Line between Greenbelt and College Park.

Minnesota Avenue – New Carrollton, Orange Line, May-June (Dates to be announced)

Continuous single tracking will significantly reduce Orange Line service

Shady Grove – Twinbrook, Red Line, June (Dates to be announced)

Continuous single tracking will significantly reduce Red Line service north of Grosvenor.