Boston Harbor Tunnel Sinking — MBTA Plans Repairs

Boston's 120-year-old MBTA Blue Line tunnel under harbor requires major repairs

Blue Line Tunnel Under Boston Harbor Sinks

Boston's MBTA Blue Line tunnel beneath Boston Harbor is sinking and needs major infrastructure repairs, transit officials said. The underwater tunnel serves about 55,000 riders on weekdays who travel between East Boston, downtown, and communities north of the city. Officials haven't released cost estimates or a detailed repair timeline for the century-old tunnel.

The Blue Line tunnel opened in 1904, making it one of the oldest underwater transit tunnels in the United States, according to MBTA records. The tunnel's age—over 120 years—provides context for why infrastructure problems like sinking would occur, transit experts say. Officials didn't provide specific measurements of how much the tunnel has sunk or technical details about the structural assessment. The agency said the issue requires attention but didn't characterize it as an immediate safety crisis.

The Blue Line operates 5.9 miles of track serving 12 stations across the system, MBTA data shows. Phillip Eng, the agency's General Manager and Chief Executive Officer, has addressed the tunnel infrastructure issue, though the agency hasn't issued a comprehensive press release with project details. Specific service impacts during repairs weren't announced. The tunnel carries roughly 4.6% of the MBTA's total weekday ridership of approximately 1.2 million passengers.

Officials said repairs will move forward but didn't announce when work will begin or how long the project will take. The MBTA hasn't said whether repairs will require service disruptions or schedule changes on the Blue Line. Funding sources for the tunnel repairs weren't disclosed. Transit agencies typically conduct engineering assessments before announcing detailed project timelines, but officials didn't say when additional information will be available.

The tunnel repairs will eventually affect thousands of daily commuters who rely on the Blue Line for trips between East Boston and downtown Boston. Officials said they'll release more details before implementation begins, though a specific timeline wasn't provided. Riders can check Moovit for real-time Blue Line service updates and schedule information as the repair project develops.