Portions of the Hynes Convention Center (Hynes) are located directly over I-90, the Massachusetts Turnpike.  A fifty-year-old, cast-in-place concrete slab suspended from the underside of the Hynes served as the ceiling for the western portion of the Prudential Tunnel.  On behalf of the building owner, who is responsible for maintenance of the tunnel ceiling, SGH performed annual condition assessments and recommended repairs for the ceiling and ceiling-support system.  As the ceiling reached the end of its useful life, SGH designed a demolition plan and observed its removal over a period of several months.