Officials say essential work to widen more than half of the Green Line Extension tracks will take days, not months — and the project can be completed without a full shutdown.

MBTA General Manager Phil Eng on Tuesday said the contractors who built the misaligned tracks will pay to correct them, and that the team responsible for the flawed project has been replaced.

He added that the new construction team plans to start realigning the tracks as early as next week. The repair can be done between 9 p.m. and 5 a.m. over a two-week period. Shuttle buses will be provided for riders using the system after 9 p.m.

Although relieved that the fix will not be as disruptive as expected, local elected officials still have questions about how the track conditions were not revealed to the public when they were discovered in 2021, and why the MBTA proceeded to open the extension in December 2022.

Eng, who became MBTA general manager in April, said he only recently became aware of the problem. He publicly disclosed the issue last week.

Instead of correcting the problem before the tracks were laid, the ties now must be torn up and reconfigured to provide the proper gauge of 56 ½. Along some stretches of the rail line, the distance between rails was as much as a half inch too narrow. Besides causing more wear to the trains’ wheels, the condition increases the risk of derailment at full speed, requiring trains to travel more slowly.

Somerville Mayor Katjana Ballantyne and state Rep. Michael Connolly, who represents Cambridge and Somerville, both said they have heard from frustrated constituents after Eng revealed the problem.

"The most recent GLX update from MBTA is obviously not what any of us wanted to hear,” Ballantyne said.

“People have been bombarded with bad news from the T,” Connolly said. “And there's a range of negative feelings between desperation, hopelessness, anger and frustration.”

Connolly also questioned whether former Gov. Charlie Baker and his administration knew of the problem. A spokesman for the former governor said Baker had no such knowledge before he left the governor’s office.

Medford Mayor Breanna Lungo-Koehn is pleased that Eng revealed the design issue as soon as he learned about it, but agreed that action should have been taken sooner.

”They should have been more proactive, even if that meant delaying for another month. It should have been brought to design standards before opening,” she said, ”because we're only a year out and we have wear and tear and design standard issues that were known about. That's not OK.”

Lungo-Koehn is asking for the same level of alternative bus service that was provided during the Orange Line shutdown last year. And she wants plenty of advance notice from the T so residents can prepare, saying a lack of communication has been a problem in the past.