State Implementation Plan (SIP)

The SIP – as approved in regulation by the Massachusetts Department of Environmental Protection and the U.S. Environmental Protection Agency – requires that MassDOT and the MBTA complete the transportation improvements listed below.
  • Green Line Extension to Medford Hillside.
  • Green Line Extension to Union Square (Somerville).
  • Upgrade of the MBTA Fairmount Commuter Rail Line, including the construction of four new stations: Four Corners (Dorchester) and one new station each in the Dorchester, Mattapan, and Roxbury neighborhoods.
  • Construct 1,000 new parking spaces serving commuter transit facilities (complete).

Together, these projects are intended to reduce certain air pollutants in eastern Massachusetts. Questions about the SIP projects should be directed to the Office of Transportation Planning.


SIP Public Meeting

The public meetings was held:


  • On: Tuesday, September 11, 2018 at 2:00 PM until all present have offered comments and from 5:00-6:00 PM. The 5:00 PM public meeting will be extended after 6:00 PM as needed to allow all interested parties to present testimony.

  • At: MassDEP office, 2nd Floor, Conference Rooms A, B, & C One Winter Street, Boston, MA 02108.