Red-Blue Connector

Alignment

The Red and Blue lines are the only two MBTA subway lines that do not meet. Riders between them now have to change twice, via the Green or Orange Line, which adds to crowding at Park Street and Downtown Crossing. The Red-Blue Connector would extend the Blue Line west from its current terminus at Bowdoin, under Cambridge Street, to a new underground Blue Line platform at Charles/MGH. The new platform would sit just east of the existing Red Line headhouse, so riders could transfer without leaving fare control. Charles/MGH was rebuilt in 2003–2007 with room for this platform. The extension is roughly 2,200–2,500 feet (about 0.4 miles), and it would put Massachusetts General Hospital and Mass Eye and Ear on the Blue Line, which serves East Boston, Logan Airport and Revere.

The MBTA’s preferred design is a shallow cut-and-cover tunnel dug down Cambridge Street and then covered, with the street rebuilt on top. This replaced the deep bored tunnels in the 2010 environmental report after a 2018 study found cut-and-cover substantially cheaper. Bowdoin station would close and serve as a construction staging area. In 2023 the MBTA estimated five years of construction. Mass General’s planned rebuild of its Cambridge Street frontage sits directly above the alignment.

Updates

2026-04 — FY2027–31 capital plan again funds planning only

The MBTA’s draft FY2027–31 Capital Investment Plan included money only for the connector’s planning phase. A Better City urged the T to move the project past planning so it could compete for federal infrastructure funds over the next five years.

2025-04 — Construction funding rejected in capital plan

The FY2026–30 capital plan budgeted $19 million for preliminary engineering and environmental review, but left the $850 million project out of the construction program. Budget planners expected to afford only a little over $1 billion in new projects and rejected $12.5 billion of the $13.5 billion requested.

2023-11 — State requires a supplemental environmental report

After the MBTA filed a Notice of Project Change with the state’s MEPA office on October 2, 2023, the state issued a certificate on November 13 requiring a Supplemental Draft Environmental Impact Report. The MBTA says it is doing preliminary engineering to complete state and federal environmental reviews.

2023-10 — Public meetings on cut-and-cover design

At public meetings at MGH and in East Boston, the MBTA presented preliminary plans for cut-and-cover construction and the closure of Bowdoin. The MBTA then estimated completion in 2031, with five years of construction, at a projected $850 million, and said the project was only partly funded. Residents raised concerns about the effects on Cambridge Street traffic and bike lanes.

2021-06 — Concept design priced at $850 million

The MBTA’s concept design for a 2,200-foot cut-and-cover extension was estimated at $850 million. That included $270 million for the tunnel, $60 million for the station, $20 million to rebuild Cambridge Street, and large allowances for contingency and inflation. With $15 million on hand for design, the T said construction could run from 2025 to 2030 if funding were found. None was committed.

2015-12 — Federal design mandate dropped

The state had committed to the connector in the early 1990s as environmental mitigation for the Big Dig. It published a 2010 draft environmental report for a deep-bored version estimated at $413 million, then dropped the commitment for lack of funds. In December 2015 the EPA removed the requirement in the state’s air-quality implementation plan that the MBTA complete the design.