Metro commuters ride an Orange Line train in Falls Church, Va., in June. (Amanda Voisard/For The Washington Post)

Metro’s next SafeTrack surge was pushed back a week — to Aug. 27 — a last-minute change for Northern Virginia commuters who have already dealt with more than their share of disruptions caused by the agency’s long-term maintenance blitz.

Surge No. 8, which requires 16 days of continuous single-tracking between Franconia-Springfield and Van Dorn Street stations on the Yellow and Blue lines, will continue through Sept. 11. Metro officials last week also added three consecutive weekend shutdowns to the surge so that crews can rehabilitate a switch in the area.

The changes are part of a revised SafeTrack plan announced last week. Officials said the revised schedule is needed for aggressive work to be performed on interlockings — the points where trains change tracks — and the infrastructure faulted in last month’s derailment at East Falls Church.

The changes also address new federal safety recommendations, and account for the impact excessively hot weather and high humidity have had on SafeTrack work, Metro said.

The year-long Metrorail rehabilitation plan includes 15 projects that will require the longest stretches of single-tracking and station shutdowns.

But even with the last-minute changes, Northern Virginia transportation officials are confident that commuters affected by the upcoming service interruptions are ready. After all, they note, they’re practically SafeTrack experts at this point.

So far, four of the seven Metro surges have targeted stretches of the Orange, Silver, Blue and Yellow lines in Northern Virginia. The eighth and ninth phases of maintenance work are focused on tracks in Fairfax County. Surges 11, 13, 14 and 15 are also NoVa-centric.

“I don’t think they’ve adjusted,” said Metro board member Jim Corcoran, who represents Virginia, acknowledging that commuters continue to air grievances about daily SafeTrack frustrations. “But they’ve definitely adapted.”

Some Metro board members have criticized the late notice of the changes to the SafeTrack schedule. Last week, Metro board member Christian Dorsey, who also represents Virginia, worried that local agencies helping to augment Metro’s limited service during surges were “left playing catch-up” when they discovered four days before the scheduled start of Surge No. 8 that they would need to hold off on their efforts for a week.

But Tonya A. McCreary, spokeswoman for the Fairfax County Department of Transportation, said the last-minute rescheduling probably won’t cost her agency extra money, and she said that communication with Metro had been frequent in recent days.

“We really are just rolling with changes as they come about,” McCreary said. “We’ll find a way to get through it.”

Metro is expected to announce the revamped schedule for Surges 10 to 15 in mid-September. That’s about the same time that Surge No. 9 is set to start: The 42-day stretch of aggressive repair work will begin almost a week later than scheduled, on Sept. 15. During that phase of the project, there will be continuous single-tracking between Vienna and West Falls Church stations.

Metro has said that the delayed schedule came as a result of slower-than-expected progress in the first stages of SafeTrack resulting from hot weather and the need to address new safety recommendations. Additionally, in the aftermath of the July 29 Silver Line derailment caused by degraded tracks at a juncture where trains cross to shift from one set of tracks to another, officials decided that it would be important to use SafeTrack to tackle similar spots throughout the system — even if it meant retooling the original calendar.

“Metro is committed to delivering on results, but things do go different than scheduled sometimes,” Corcoran said.

To that effect, Metro has planned a series of weekend shutdowns on short segments of the line: On Aug. 27 and 28, Metro will operate buses instead of rail service between Franconia-Springfield and Van Dorn Street stations. That same shutdown will also occur on Sept. 10 and 11.

Throughout Labor Day Weekend, Sept. 3-5, Metro riders will see a line segment shutdown from Franconia-Springfield station to King Street-Old Town station.

The new schedule for Surge No. 8 and the weekend shutdowns also coincides with the start of the school year in Fairfax County — and the accompanying spike in traffic as parents ferry school-age children during the morning rush hour. (Previously, Surge No. 8 was scheduled to conclude just before students returned to class.)

The shift in timing might be a problem, as Metro commuters who opt to drive during surges may encounter heavier traffic than usual. But McCreary took an optimistic tack, pointing out that by starting the surge later, there won’t be as many surprises once Surge No. 9 rolls around.

“With the rescheduling, it gives us a little extra time for students and parents to reassess their commutes,” McCreary said.

Sandy Modell, general manager of Alexandria’s DASH bus system, said her agency was able to quickly adjust its schedule to match Metro’s new calendar.

“Our goal is to get people where they need to go. We think we have it covered in terms of alternative options for people who would normally rely on rail,” Modell said.

DASH buses have seen a double-digit drop in ridership during previous surges, she said, as residents often use the buses in conjunction with trains ferrying them into the city. More recently, she said, they’ve switched to cars.

This week, next week — it doesn’t really matter, Modell said: She’s just looking forward to things getting back to normal.

“When people perceive Metrorail as a safer system, after SafeTrack — we’re hoping to see ridership on DASH go up,” Modell said.