San Francisco, California
London, United Kingdom
Joint International Concrete Repair Institute/SEC Dinner Meeting
Shoring Up The Hynes, From Decision to Complex Execution:
Exploring the Demolition & Removal of 42,000 s.f. of Concrete Spanning Over 8 Lanes of Interstate I-90
The Hynes Convention Center (Hynes) is located in the heart of Boston’s historic Back Bay neighborhood. Portions of the Hynes span over Interstate I-90 (Massachusetts Turnpike) and Amtrack/MBTA Rail line on a section of the highway known as the Prudential Center tunnel. Two massive 50 yr old cast-in-place concrete slabs, suspended from the underside of the Hynes, served as the ceiling for the westernmost 420 ft of the tunnel, comprising a 42,000 sq ft area. The concrete ceiling spanned four eastbound and four westbound travel lanes and served as both fire and acoustical separation between the tunnel and the Hynes.
The Massachusetts Convention Center Authority (MCCA) owns the Hynes and has responsibility for maintaining specific Hynes structural elements within the tunnel. On MCCA’s behalf, Simpson Gumpertz & Heger Inc. (SGH) performed rigorous annual inspections of the ceiling and ceiling-support system over several years to evaluate its condition and recommend repairs. SGH and the MCCA ultimately determined that the concrete ceiling over Interstate I-90 had reached the end of its useful life and needed to be removed. Coordinating and safely performing the ceiling demolition work in the public spotlight with the lowest possible traffic disruption. To navigate this challenge, the project team performed the work in two phases: demolition preparatory work and demolition work.
The demolition preparatory work, such as supplemental steel installation and pre-demolition saw cutting, was limited to nighttime work over two to three closed traffic lanes, with one to two live traffic lanes immediately adjacent to the work zone. Demolition work (final saw cutting and ceiling removal) was completed over three weekends, when either the eastbound or westbound tunnel was shut down in its entirety. Each weekend shutdown was limited to 55 hrs. Work entailed creating traffic lane shifts and crossovers; slab saw cuts and slab removal; roadway and tunnel cleanup; and restoring normal traffic routes for the Monday morning commute.
The contractor developed a simple yet elegant solution to remove the ceiling: tractor trailers equipped with jacks and cargo containers, allowing the contractor to both shore and remove the ceiling segments with one piece of equipment. With one shoring rig in each lane, the contractor performed the final saw cuts between the trucks. Once the contractor disengaged each lane-wide by 30 ft long slab segment from the rest of the ceiling, it lowered the jacking frame and drove out of the tunnel to a staging area. At the staging area, forklifts removed segments from the shoring rigs and loaded them onto transport trucks for disposal and recycling. Shoring rigs then repeated the process below the next 30 ft segment and proceeded along the tunnel.
After months of intensive preparation and complicated coordination, the contractor safely removed the ceiling ahead of schedule, resulting in savings for the owner and a significant reduction in public impact. The collaborative partnership among the owner, the consulting engineers, the construction manager, and the contractors allowed the team to work cohesively to solve technical and logistical challenges throughout the construction process.
Corey Brett, P.E.
Simpson Gumpertz & Heger, Inc.
Cory Brett has more than fifteen years of experience in structural engineering, which includes designing foundations and retaining walls, designing transportation-related structures (e.g., bridges, tunnels, and sign support structures) and designing, investigating, and rehabilitating buildings of all types. He is a member of the Post-Tensioning Institute Committee DC-80, for repair and rehabilitation of post-tensioned structures, and a registered professional structural engineer in Massachusetts.
Attendance to this seminar is worth 1.0 New York PDH Credits
5:30 – 6:30 pm Registration, Social Hour
6:30 – 7:15 pm Dinner
7:15 – 8:15 pm Program
COST: SEC/CSCE Members: $40.00 per person
Non-Members: $45.00 per person
RESERVATIONS: Reservations are required. Please reply by 4:00pm, Friday, May 6th.
Registrations after May 9th will incur a $5 surcharge.