Workers excavate the Plymouth Street tunnel as part of building Maryland's light-rail Purple Line between downtown Bethesda and the New Carrollton Metro station. (Doug Kapustin for The Washington Post)

Workers excavating a tunnel beneath a Silver Spring neighborhood as part of the construction of the light-rail Purple Line have stopped the noisiest overnight work that some residents had complained was waking them up at all hours, project officials said Thursday.

The rock hammering beneath homes in the Long Branch area east of downtown Silver Spring has been halted between 9 p.m. and 6 a.m., said Gary Witherspoon, a spokesman for the Maryland Transit Administration. He said the MTA and its contractor are still “testing” to determine what caused the complaints.

Maryland transit officials had previously told residents that they were sympathetic to their complaints but that the contractor needed the option of hammering through bedrock round-the-clock to keep construction on schedule. The Purple Line is projected to begin carrying passengers in fall 2022.

The change came after five residents met Monday with Maryland Transportation Secretary Pete K. Rahn. After hearing their concerns, Rahn told the group the nocturnal noise was “not acceptable,” according to a video recording of the meeting.

Resident Annie Tulkin said she hasn’t heard any overnight hammering since Monday. The noise used to jolt her and her husband awake, she said.

“It’s been pretty good,” Tulkin said of her sleep this week. “We still hear a little bit of noise, but it’s nothing like the jackhammering that we heard before.”

Kevin Hawkins, of Neighbors Impacted by the Manchester Tunnel, said he and four other residents showed up unannounced at Rahn’s office and were pleasantly surprised when he agreed to meet with them. While many residents look forward to the Purple Line being built, he said, many, including children and older residents, had been losing too much sleep since the nighttime hammering started in September.

“It feels really good,” Hawkins said of sleeping uninterrupted. “There’s still a lot more [construction] to come, but this is a nice victory.”

Tulkin and Hawkins said they’ve asked state officials for a promise in writing that the overnight hammering will not resume during the rest of the tunnel’s excavation.

Witherspoon did not respond to questions about how the schedule change will affect the project’s timeline and cost but said the state and contractor are looking for ways to build the Purple Line “on time, at the best value, and with the least disruption to the community.”

State transit officials have said the 1,000-foot tunnel is necessary to carry Purple Line trains beneath the neighborhood off Plymouth Street because the surface terrain is too steep for light-rail trains.