In November, MBTA General Manager Phillip Eng unveiled a comprehensive plan to repair tracks across the entire subway and trolley system and lift all speed restrictions by the end of 2024. While previous track repairs were made in response to specific incidents on a case-by-case basis, the new plan is an organized effort to systematically remove all track restrictions.

Accomplishing the goal will require nearly two dozen multi-day closures of segments on each of the four subway lines ranging in duration from four days to 21 days. There are 152 slow zones where speeds are limited to 25 mph or less.

"We want to bring our trains back to full max speed [40mph] by rebuilding and restoring our track infrastructure,” Eng said.

To do that most efficiently, parts of the system need to be shut down for extended periods of time, allowing crews 24/7, unimpeded access to complete the needed track work. Eng admits the unprecedented service disruptions will have a serious impact on riders, but as he puts it: “short-term pain is needed to make long-term wins.”

Eng’s plan began with the implementation of a 10-day shutdown of the Green Line’s D branch in December and will be expanded in earnest this month.

From Jan. 3-12 and again from Jan. 16-28, Green Line service will be suspended on the Green Line’s B branch between North Station and Babcock Street, on the C and D branches between North Station and Kenmore and on the E branch between North Station and Heath Street. However, service will operate Jan. 13-15 during the Martin Luther King Jr. Day holiday weekend. Information on shuttle buses or other transit alternatives is available on the MBTA website.

On the new Green Line extension between North Station and Union Square or Medford/Tufts, work continues to correct tracks that were installed with a gauge that was too narrow. To accommodate that work, GLX service will not operate on the weekends of Jan. 6-7 and Jan. 20-21, while evening rail service will end at approximately 8:45 p.m. and be replaced with shuttle buses Jan. 8-11, Jan. 16-18 and Jan. 22-25.