MBTA Haymarket Tunnel Station
A component of a major development project in downtown Boston, Massachusetts, required demolishing a portion of the Government Center garage. On 26 March 2022, three precast concrete tee beams and a construction vehicle fell to the ground from the eighth and ninth floors of the partially demolished garage, striking directly over the Haymarket Station tunnel. SGH supported the Massachusetts Bay Transportation Authority (MBTA) by identifying damage potentially caused by the collapse and analyzing the effects from the impacts on the tunnel that carries the MBTA’s Green and Orange Lines.
Immediately following the collapse, the MBTA closed Haymarket Station and the tunnels between North Station and Government Center and worked to confirm that no worker or member of the public were near the tunnels. Once it was safe to enter, SGH conducted multiple site visits to make visual observations from the topside and underside of the tunnel, and document the existing configuration of the structures and collapse debris.
We executed a multi-tiered analysis, ranging from hand calculations to detailed finite element modeling, and oversaw physical proof testing to validate our results. With service halted, the MBTA needed to promptly understand the implications of the collapse. SGH responded quickly and creatively with a pragmatic approach, leveraging field observations, analyses of varying complexity, and proof testing to give the MBTA confidence that it was safe to resume Green Line train service.