The MBTA announced today it will be shutting down Green Line service from Government Center to Union Square from Aug. 22 to Sept. 18 — nearly the same timeframe as the closure of the Orange Line announced two days ago.

Shuttle buses will be deployed to transport passengers between Government Center and Union Square along the Green Line extension. The MBTA says the temporary shutdown of the Union branch will provide contractors with around-the-clock access to the tracks and overhead wire system, enabling them to safely and quickly complete work deemed critical to the opening of the new Medford branch, which was originally slated to open to passengers this month. The agency now says the Medford branch will open in late November.

T officials say the delayed extension project is due to a number of contributing factors, including additional work and retesting of the Medford branch’s power systems. The start date has also been affected by the availability of safety and operational support crews who were previously prioritized for the Green Line extension but reassigned to other critical MBTA construction work, including in the MBTA’s response to safety directives from the Federal Transit Administration.

The agency says this diversion in service is also necessary to allow for continued work at the private Government Center Garage project, where demolition work has previously disrupted Green and Orange Line service.

Scheduled activities include:

  • Adjustments to the overhead wire on the East Cambridge Viaduct that will eliminate a temporary 10 mph speed restriction, allowing trolleys to operate at the system’s designed speed of 25 mph on a permanent basis.
  • The final testing and integration of track switches, power lines, signal equipment and digital communications between the Green Line’s currently operating Union branch, the soon-to-be-operational Medford branch, and the MBTA’s Operations Control Center.
  • The installation of the last remaining sound wall panels along the Union branch and non-critical work items along the Medford branch.
  • Additional last work and various outstanding construction items along the Union and Medford branches’ tracks, stations and rights of way.