The MBTA announced Thursday that it is accelerating planned infrastructure improvements in 2020, which will result in service disruptions and shutdowns on all the subway lines — including two separate one-month shutdowns on the Green Line — and the commuter rail.

The transit agency said the goal of accelerating the projects is to improve service, reliability, and safety on a “faster timeline,” delivering the work eight years ahead of the original schedule.

“MBTA customers deserve better service faster, but the T can’t deliver on modernization without disruption, including weekday station shutdowns,” said Stephanie Pollack, transportation secretary and CEO of MassDOT. “During the shutdowns, we will help people get to where they are going on shuttles or other train lines. Most importantly, the temporary inconvenience will be worth it, delivering safer and more reliable service in months instead of years.”


The work ranges from track replacement to upgraded intersections and station improvements, the MBTA said in a statement. The disruptions also include an 11-month shutdown of Green Line service between North Station and Lechmere as part of the agency’s work on the Green Line Extension project.

“During diversions of regularly scheduled rail service, the MBTA takes steps to provide replacement service to ensure customers can reach their intended destinations,” the transit agency said. “In certain cases, the MBTA increases the frequency of parallel services to accommodate customers displaced by a diversion. In other cases, the MBTA provides accessible shuttle buses – operated by the MBTA or a private carrier – that are specially designed to account for passenger travel patterns during these diversions.”

The MBTA has created a website with an interactive map for riders to track the upcoming work and service changes. Below, the planned service disruptions MBTA has scheduled in 2020.

Green Line

B Branch:

When: Three weekend diversions in June.

Where: From Boston College to Babcock Street.

Mitigation: Shuttle bus service.

Reason: To replace track and upgrade intersections.

C Branch:

When: A 28-day closure, from the beginning of July through the beginning of August.

Where: The entire street-level branch, from Kenmore to Cleveland Circle.


Mitigation: Shuttle buses replacing rail service.

Reason: To allow for the replacement of track and upgrading intersections.

D Branch:

When: Evening and weekend diversions throughout 2020.

Where: Between Reservoir and Kenmore:

Weekends, February 1-March 1, 2020

Weeknights, February 24-28, 2020; Starting at 8:45 p.m.

Where: Between Newton Highlands and Kenmore:

Weeknights, March 2-26, 2020; Starting at 8:45 p.m.

Weekends, March 6-29 and May 29-31, 2020

Mitigation: Shuttle bus service.

Reason: For track and signal improvements and work on the Fenway Portal Project.

E Branch:

When: A 28-day closure during the month of August.

Where: The entire street-level branch, from Prudential to Heath Street.

Mitigation: Shuttle buses and an enhanced Route 39 bus service.

Reason: To replace track and upgrade intersections.

—

When: 11 months, from May 2020 through April 2021.

Where: Between Lechmere and North Station.

Mitigation: Shuttle buses replacing service between the two stations.

Reason: Work for both Green Line Extension and Green Line Transformation on the Lechmere Viaduct in coordination with the rebuilding of the elevated segment of track through East Cambridge and the realignment of the track to a new, relocated Lechmere Station.

When: 11 weekends of diversions, January through April.

Where: Between Alewife and Harvard.

Mitigation: Shuttle bus service. Regular train service will run on the following weekends:

January 18-19

February 1-2

February 15-16

March 14-15

April 18-19

Reason: Tunnel leak repairs, Harvard Station brightening, and repairing 32,000 feet of track.

—

When: Nights and some weekends, March through August.

Where: Between Braintree and Quincy Center:

Weeknights, March 16-May 28: Mondays-Thursdays after 8:45 p.m.

Weekends, May 1-May 17: Fridays after 8:45 p.m., and all day Saturdays and Sundays

Sunday night and weeknights, May 31-June 18: Sundays-Thursdays after 8:45 p.m.

Mitigation: Shuttle bus service, as well as added commuter rail service on weekends in May.

When: Weekends, January to February.

Where: Between Sullivan Square and Tufts Medical Center.

Mitigation: Shuttle buses.

—

When: Weekends, June through July.

Where: North Station.

—

Reason: Replacing track and associated systems at Wellington yard and station brightening.


When: Weekends, May 16-June 21; Weekends, August-November.

Where: Between Bowdoin and Airport.

Mitigation: Shuttle buses.

—

When: Weekends, May 2-10.

Where: Between Maverick and Airport.

Mitigation: Shuttle buses.

Reasons: Performing tunnel weather-proofing work, repairing isolated cracked rail within tunnel areas, opening tunnel niches to build new truck pads, performing tunnel leak repairs, and removing inactive cables and ducts.

When: Weekends, August through December.

Where: Between South Station and World Trade Center.

Mitigation: Service won’t shut down, but buses will run at street level during those weekends.

Reason: To waterproof compartments at Courthouse Station and East tunnels to prevent future leaks, and enhance station conditions.

Commuter Rail

Franklin Line

When: Weekends, January through March.

Where: Between Forge Park/495 and South Station.

Mitigation: Shuttles between Forge Park/495 and Readville, bypassing three stations. Connecting train service between Readville and South Station will be on the Fairmount Line.

Reason: Construction of 39,000 feet of new track.