Shore Line Bridge Replacement
Originally constructed in 1898, the Shore Line Bridge carries the Massachusetts Bay Transportation Authority (MBTA) commuter rail and CSX freight lines over Amtrak’s Northeast Corridor. MBTA needed to replace the existing steel through-truss railroad bridge due to the poor condition of the existing foundations. SGH assisted the contractor, Barletta Heavy Division (Barletta), by providing construction engineering services to facilitate removing and replacing the bridge with a new steel through-girder bridge.
MBTA required Barletta to remove the existing bridge during one five-hour overnight shift. To accomplish this, Batletta would have to remove the bridge in a single heavy lift. SGH evaluated the feasibility of this approach and helped Barletta develop a plan to implement this lift. Highlights of our work include the following:
- Calculated approximate stresses in the existing truss members as part of feasibility studies for various pick options
- Developed a rigging arrangement allowing Barletta to lift the truss from pick points at the truss’s top chords, which eliminated the need for a large and expensive longitudinal spreader beam and was significantly more stable than attaching rigging to the bottom of the truss
- Developed conceptual sketches of the rigging and the hoisting operations, including plans showing the crane pick radii
- Analyzed the existing bridge for forces during the hoist and designed lifting components, including new hoist lugs, shackles, slings, and the small transverse spreader beam
- Prepared a package of calculations and sketches to support the lift and submitted it to MBTA for their review
By using our plans, Barletta successfully removed the existing bridge superstructure in approximately three hours.