A satellite view of the Branch Avenue interlocking. (Google Maps)

A blitz of round-the-clock track work will close two Green Line stations for 16 days beginning Saturday, as Metro embarks on the first round of extended repairs in its post-SafeTrack preventive maintenance program.

Two stations, Branch Avenue and Suitland, will be closed from Saturday through Aug. 20 while crews work to replace a major interlocking outside the Branch Avenue station. The work zone will extend to a third station, Naylor Road, on consecutive weekends from Aug. 12 to 13 and Aug. 19 to 20, Metro said.

Metro says buses will replace trains between Branch Avenue and Naylor Road for the 10 weekdays of the work surge. On weekends, the bus bridges will extend from the Branch Avenue to Southern Avenue stations.

“Customers who normally use Branch Ave or Suitland stations are strongly encouraged to consider using Anacostia or Southern Ave instead, travel during off-peak times or use alternate travel options,” Metro said in a news release.

All three of Metro’s upcoming work blitzes are focused on interlockings, the complex mechanism of switches and signals that work in concert to direct trains to the proper track.

“Rebuilding the interlocking is a complex process, involving the replacement of four switches that are near the end of their useful life and requires simultaneous work on both tracks,” Metro said of the Branch Avenue crossover.

The work zone stretches 4.5 miles and will encompass signal upgrades, power cable renewals and the replacement of about 1,500 crossties — the wooden beams that space the tracks at the proper distance on aboveground portions of track. The crossover itself is built on concrete and stretches about 450 feet long and 50 feet wide, according to a June interview with Andy Off, Metro’s assistant general manager of rail services.

Off estimated that the complex, double-crossover mechanism will require just under a mile’s worth of grout pads, the components that keep the running rails at the correct elevation on concrete track. The project also involves tearing out the concrete supporting structures, pouring new concrete and installing new steels rails, Off said.

SafeTrack, Metro’s year-long rehabilitation program that concluded in June, was largely geared at replacing crossties. More than 50,000 of the components were replaced during the course of the program, Metro said, reducing the percentage of defective ties from 22 to 2 percent. Metro has said that the new round of work blitzes, which is more spaced out and targets more-specific sections of the system, doesn’t constitute another SafeTrack.

Still, two more rounds of extended track work are scheduled for the upcoming year. In an interview in June, SafeTrack Director Laura Mason compared the cost of an upcoming Red Line blitz with that of SafeTrack Surge 10: $14 million.

For that project, the Takoma Metro station will close from Nov. 25 through Dec. 10 so crews can rebuild an interlocking outside that station, and the Huntington and Eisenhower Avenue stations will be closed from May 12 through May 27 for a similar crossover rehabilitation.

“These planned capital improvement projects are necessary to ensure the tracks are properly maintained, resulting in fewer delays for customers due to track issues,” Metro General Manager Paul J. Wiedefeld said in a statement. “The long-term benefit is a safer, more reliable system and customers should experience a smoother, better ride.”