The Diamond Ring

Proposed MBTA System Map

Proposed MBTA System Map, with the Diamond Ring shown in yellow

[Update] New reports on BRT and TOD in Boston have been released since this workshop.  See, produced by the Greater Boston BRT Study Group, and, produced by MAPC and the Dukakis Center.

The Diamond Ring represents a new approach to an old idea.

Concepts for a circumferential transit line through the dense communities surrounding Boston date back at least to the Boston Transportation Planning Review of the 1960s. Such a line would supplement the predominantly radial rail transit network, generating significant travel time savings and freeing capacity in the downtown rail network. The proposed corridor will help alleviate the growing congestion in the transit network’s downtown core by improving connections between existing rail lines and two major employment centers, the Longwood Medical Area and Kendall Square, while also increasing transit access for surrounding residential communities.

The Massachusetts Bay Transportation Authority (MBTA) began an official study of the circumferential corridor in 1995. It dubbed the corridor the Urban Ring, identified major destinations to serve, and established an implementation timeline. Originally intended as Phase 1 of the Urban Ring, cross-town (CT) buses now travel circumferential routes that connect radial lines in Boston and the neighboring towns of Cambridge and Somerville, but these lines have generated little ridership. Subsequent phases of the Urban Ring project were put on hold in 2008, but recent planning efforts have revived the possibility of new BRT corridors in the city.

We sought to produce innovative designs for circumferential transit that would inspire renewed attention for this corridor, as well as build ridership. Our proposal rebrands the western half of the Urban Ring as the Diamond Ring, a nod to the famous Emerald Necklace park system it intersects. This corridor traverses a cross-section of Boston’s urban areas. The corridor would occupy varied existing right of way configurations, from abandoned or lightly used railroad tracks to wide avenues to narrow, winding streets, in addition to new potential new bridges.

In the north, the corridor starts in Somerville’s Assembly Square and Inner Belt, postindustrial brownfields that are in varying stages of master planning and redevelopment. After passing intermodal connections with the Orange Line and under-construction Green Line Extension, the corridor enters East Cambridge, a mix of retail establishments and residential neighborhoods. In the burgeoning Kendall Square commercial district, it intersects the Red Line subway before traversing the MIT campus and the residential neighborhoods of Cambridgeport. Crossing the Charles River Basin, the established residential areas of Brookline, and the branches of the Green Line that run along the Emerald Necklace parks created another major set of design challenges. The final segment addresses the challenges of serving both the Longwood Medical Area, a congested academic and medical employment cluster, and the historically marginalized neighborhood of Dudley Square in Roxbury. Across these contexts, we seek to tap into the revived focus BRT is receiving in Boston with a new vision for this corridor and with the hope that integrated design and strategic planning can move this long-stalled project forward.

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