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

An unplanned power shutdown between the East Falls Church and Virginia Square stations Wednesday morning sent throngs of Northern Virginia commuters scurrying for shuttle buses — and resulted in a gnarly start to Metro’s fifth SafeTrack surge.

It was an unlucky morning for the system, after some had assumed that the repeat nature of this latest surge would mean that the 12-day bout of maintenance work on the Orange and Silver lines would unfold smoothly.

But Wednesday morning’s commuting struggles were also a sign of a more worrisome development: Ridership during SafeTrack surges is creeping back toward normal, and the combined challenges of a planned single-tracking schedule, the potential of surprise service disruptions and growing crowds could lead to more commuting woes before this phase of SafeTrack concludes.

Wednesday’s major disruption occurred near the end of the morning’s peak travel period. Metro said crews worked early in the morning to begin setting up for around-the-clock maintenance work on the outbound tracks and to make sure they’d be able to get unfettered access to that side of the railway.

The fifth surge in Metro’s long-term maintenance overhaul known as SafeTrack runs July 20 - July 31 on the Silver Line. Take a look at how it will affect your commute. (Danielle Kunitz,Claritza Jimenez/The Washington Post)

Crews redirected power from cables on the outbound side, but by the time service had begun in the morning, they realized that there were additional cables that needed to be disconnected to ensure the safety of workers, the agency said.

“What we needed to do was akin to moving utilities to allow for any kind of construction job,” Metro spokesman Dan Stessel said.

Crews weren’t allowed to start any work on the tracks until that power was disconnected, but redirecting the power required a 15-minute shutdown on both sides of the tracks, and morning service had already begun to swing into high gear, Stessel said. So Metro officials decided to wait until the heaviest part of the morning peak travel period had occurred before shutting down the stretch of the system.

At 8:29 a.m., Metro made the announcement via Twitter: Shuttles buses would replace trains between the three affected stations on the Orange and Silver lines for 30 minutes, beginning at 10 a.m., although Stessel said later that the service interruption ultimately lasted half that time. But it wasn’t until 9:30 a.m. that Metro sent an alert to customers about the shutdown.

Even so, the interruption sent hordes of commuters seeking spots on shuttle buses, and demand quickly outpaced the number of seats. Stessel said “the total number of customers affected was a few dozen,” but commuters posted Tweets and videos online indicating that lines for the buses stretched more than a block at the East Falls Church, Ballston and Virginia Square stations and resulted in chaotic detours that left riders frustrated and incensed.

“Metro gave wrong info @ Ballston. Shuttle driver didn’t even know where 2 go,” tweeted one rider.

The fifth surge in Metro’s long-term maintenance overhaul known as SafeTrack runs July 20 - July 31 on the Orange Line. Take a look at how it will affect your commute. (Claritza Jimenez,Danielle Kunitz/The Washington Post)

“Whoever is directing this single tracking today has clearly not been taught what worked last time. This is why everyone hates you #wmata,” tweeted another.

Stessel said the service interruption was unfortunate but necessary.

“This is the kind of work, that for safety reasons, can only occur with power down on both tracks,” Stessel said. “Sorry for the inconvenience.”

Metro also released ridership numbers for the first morning of this phase of work — and the figures show that some of the pleas for commuters to use alternate modes of transportation during planned bouts of single-tracking have begun to go unheeded.

According to Metro, 18,061 commuters entered Orange and Silver line stations west of Ballston between 5 and 10 a.m. Wednesday. That’s almost 12 percent more than the number of commuters who used those stations on the first morning of the first SafeTrack surge — which targeted the same stretch of tracks and resulted in the same single-tracking schedule.

Wednesday morning’s ridership numbers were also 8 percent more than the numbers counted on the fifth day of the first surge, when commuters presumably were more aware of what to expect and had settled into a modified version of their commute.

Ridership at Ballston on Wednesday was down more than 50 percent from the first surge, but that was likely due to a number of passengers not being able to enter the station during the temporary subway shutdown.

Anna Nissinen, spokeswoman for the Fairfax County Department of Transportation, said ridership on the county’s express bus routes remained just as high Wednesday morning as during the first surge in early June.

“We’re not necessarily concerned about the increase,” Nissinen said of the new ridership numbers from Metro. “We still think that commuters in Fairfax County are listening.”

The current round of aggressive maintenance work is scheduled to last until July 31. Workers are expected to target a stretch of rail that measures about the length of 10 football fields, and they plan to replace about 2,000 wooden rail ties.