Maintenance work to widen tracks on the Green Line Extension will not be completed until at least late January and will require several more stretches of disruption to riders.

MBTA officials announced that service on the entire 4.4-mile extension will be suspended for the weekends of Jan. 6-7 and Jan. 20-21, plus another 11 evenings over the course of January.

Trains will stop running from about 8:45 p.m. through the end of service from Jan. 8-11, Jan. 16-18 and Jan. 22-25. Shuttle buses will replace service between North Station and Medford/Tufts, but not on the one-stop Union Square branch.

The new plan represents the second substantial extension to the repair project after the contractors responsible, Green Line Extension Constructors, failed to complete work on the initial 14-night timeline they presented to the T.

GLXC built the extension, but T officials revealed in recent months that large stretches of the rails are too close together. The companies — including Fluor Enterprises Inc., The Middlesex Corp., Herzog Contracting Corp. and Balfour Beatty Infrastructure Inc. — are now responsible for widening the tracks, and MBTA General Manager Phil Eng has said he expects them to foot the bill.

January will also feature 23 total days of shutdowns on the core of the Green Line, from North Station to Babcock Street, Heath Street and Kenmore. It’s part of a sweeping plan Eng rolled out to close various parts of the system over the course of 2024 to make repairs necessary for resuming full-speed travel.