Urban Ring Project

[2] The Major Investment Study split the project into three phases, the first of which (enhanced bus service) was partially implemented.

[2][3] As of 2019[update], some interim bus service improvements have been implemented or are underway, in the absence of major funding.

Phase 2 would create six overlapping bus rapid transit lines forming a complete ring around downtown Boston.

Two express commuter (EC) routes would also have been added to provide radial service to portions of the corridor.

[8] In its FY2005-10 and draft FY2006-11 Capital Improvement Plans, the MBTA has not budgeted any money for the Urban Ring project, beyond supporting the EIR process.

Some parts of the BRT system would run in mixed traffic, including through the Ted Williams Tunnel and to the terminals at Logan International Airport.

An interim surface routing was proposed, with multiple stops in the Longwood Medical Area, while the tunnel would be under construction.

[12] Phase 3[13] would add a rail line on the most heavily traveled portion of the corridor, from Assembly Square in Somerville to Lechmere, Kendall Station, crossing Massachusetts Avenue near MIT, and connecting at Longwood Medical Area, Ruggles, and Nubian Square.

The "Silver Line Gateway" service (route SL3) has commenced, connecting Downtown and South Boston to the inner-core city of Chelsea, with an intermediate stop serving Logan Airport.