This page describes transit expansion projects in Greater Boston (and regional transit in Massachusetts), as studied, constructed or planned by MBTA, MassDOT and other municipal agencies. They can be of any transit mode: subways, buses, commuter rail, and others.
This page is part of the “Official Projects” series. Also, for unofficial transit expansion proposals by transit fans, see the “Ideas from Everyone” series.
Last updated: March 1, 2024 (revamped the page as part of the Official Projects series; split bus priority corridors into a new page)
Buses
Bus Network Redesign (BNRD)
Status: Final design completed, implementation details unreleased (as of Mar 31, 2024)
Bus Network Redesign (BNRD) is an MBTA initiative to completely transform Greater Boston’s bus network. In addition to more consistent service throughout the day and massively increased weekend service, a vast majority of bus routes will see routing changes, ranging from using a different street for a block to almost becoming unrecognizable. 6 new bus routes will be introduced, while 33 routes will have their current numbers eliminated (though many of them have the routing retained in some capacity under another route number).
The final BNRD proposal is available as an interactive Remix map and a static PDF map; I have previously made a Google Sheet detailing all route changes. Implementation is planned for 2024 through 2029.
- BNRD project main page
- New Bus Network Map main page (static map, interactive Remix map, route changes summary)
- Phase 1 service changes (to be implemented in Dec 2024)
- BNRD Final Report (Feb 2023)
- Revised (final) BNRD proposal (Nov 2022, with list of changes from the May proposal)
- Initial draft (static map, interactive Remix map) (May 2022, no longer applicable)
Silver Line Extension (SLX) (Chelsea and Everett)
Status: Alternatives Analysis completed (as of Apr 14, 2024)
Silver Line Extension (SLX) is an MBTA project to expand Silver Line bus services for the underserved cities of Chelsea and Everett. Two components were identified during planning:
- Extension of route SL3 (SL3X) to Sullivan Square;
- New route SL6 connecting Everett to either Kendall or downtown Boston.
The Silver Line Extension Alternative Analysis (SLXAA) project was completed in March 2024. The primary recommendation was to extend SL3 to Sullivan Square, after an analysis of alternatives to several Orange Line stations. The recommended alternative also included plans for transit priority along the route. On the other hand, SLXAA deferred analyses and recommendations of the new SL6 to a future study.
- SLXAA main page
- SLXAA final report (executive summary) (Feb 2024)
SL3 Extension
SLXAA identified extension of SL3 to Sullivan Square as its Locally Preferred Alternative (LPA) or the final recommendation. The proposal includes a dedicated busway on Lower Broadway, a short extension of the existing SL3 busway in Chelsea, and other segments with side-running bus lanes or occasionally mixed traffic. The extension will offer a direct connection from Chelsea and Everett Square to the Orange Line, Encore casino and many other bus routes.
Transit priority configuration along the route
1.7 miles of the extension will run in dedicated busways, 1.0 mi will (eventually) have side-running bus lanes, and 0.5 mi will run in mixed traffic. Note that of the 1.0 mi with eventual side-running bus lanes, 0.3 mi will only happen with future developments, and 0.2 mi will only be in one direction.
More specifically:
- Chelsea station to Second St: Dedicated busway (existing busway extended)
- Second St: Side-running bus lanes in the future, mixed traffic in the near term
- Spring St: Mixed traffic (southern half may have bus lanes added in the future)
- Chelsea St: Westbound bus lanes, eastbound mixed traffic
- Broadway, through Everett Square and Sweetser Circle: Side-running bus lanes
- Broadway, south of Sweetser Circle to Beacham St: Mixed traffic
- Broadway (south of Beacham St) and Alford St Bridge: Dedicated busway, on the west side of the road
- South of Alford St Bridge to Sullivan: Dedicated busway, details TBD
Other alternatives examined
Besides the LPA to Sullivan, SLXAA also evaluated two other Tier 2 alternatives: Alternative 1 to Malden Center (via Broadway and Ferry St, aka the 104’s route), and Alternative 2 to Wellington (via Santilli Connector and Revere Beach Pkwy). The preferred alternative to Sullivan stands out for the following reasons:
- Highest reliability due to highest level of transit priority
- Aligns with municipal recommendations and developments
- Most positive public support from local communities
Alternative 1 and 2’s pros and cons
Alternative 1 (Malden) has the highest projected ridership, ranks highly in pedestrian and bicycle access, and has the greatest potential for transit-oriented development (TOD). However, it is unlikely to have transit priority on Ferry St.
Alternative 2 has the shortest route to the Orange Line, and is the cheapest due to no additional modifications beyond Everett Square. However, almost half of it runs in mixed traffic, resulting in travel times comparable to driving, and thus hurting ridership.
The report also discusses several Tier 1 alternatives that were evaluated, which are local alignments between points of interest. Some examples that were not advanced to Tier 2 include a busway next to the Eastern Route right-of-way, running via Revere Beach Pkwy, and skipping Everett Square.
SL6
SL6 is a planned new bus route that would connect Everett (and possibly Chelsea) to either Kendall Square or Haymarket, via Sullivan Square. The four alternatives that advanced to Tier 2 are:
- Alternative 4: Glendale to Kendall via McGrath Hwy
- Alternative 5: Glendale to Kendall via Rutherford Ave
- Alternative 6: Glendale to Haymarket via Rutherford Ave
- Alternative 7: Chelsea (Eastern Ave) to Kendall via McGrath Hwy
Note that this is a distinct proposal in addition to SL3 extension, not as a replacement. In particular, Alternative 7 would overlap with SL3X’s LPA from Eastern Ave to Sullivan Sq.
All alternatives will provide a one-seat ride from Everett to jobs in Cambridge or downtown Boston. Additionally, Alternatives 4, 5 and 7 also provide a connection between the Orange Line and Kendall, one of the biggest employment centers outside of downtown Boston. This connection will supplement the extension of the 101 bus proposed under BNRD.
While SLXAA gave a preliminary evaluation of the Tier 2 alternatives, it ultimately deferred the SL6 proposal to future studies, as completion of ongoing planning efforts, fleet procurement and expansion of facilities are required.
SLXAA’s evaluations of SL6 alternatives
SLXAA finds that Alternatives 4, 5 and 7 to Kendall have higher ridership than Alternative 6 to Haymarket, partly due to riders transferring to the Orange Line for downtown access. Note that Alternative 6 does not assume bus lanes for certain parts of the route in Boston, which may change with additional planning efforts such as the downtown multimodal corridor.
While the report did not establish a preference between Alternatives 4 and 5, scoring metrics and comments from prior meetings favor Alternative 4 when the report was written (Feb 2024). This may be due to it having the highest projected ridership (together with Alternative 7), despite the lowest extent of transit priority. On the other hand, Alternative 5 faces concerns about congestion on the Gilmore Bridge, even though dedicated bus lanes are assumed.
Interestingly, Alternative 7 to Chelsea has one of the highest ridership projections (together with Alternative 4), despite the longest route and duplication with SL3X.
It should be noted that subsequent planning of related road projects may affect a future re-evaluation of these alignments. Notably, the redesign of McGrath Hwy that is used by Alternative 4 is proceeding without any dedicated bus lanes, while the redesign of Rutherford Ave has committed to center-running bus lanes despite no bus routes using it today. I think Alternative 5 may be favored in the future.