Due to funding constraints, the project was broken into two phases—Phase 1 included the construction of the new eastbound (Queens-bound) span and Phase 2 constructed the new westbound (Brooklyn-bound) span. Phase 2 was progressed as a traditional design-bid-build best value contract. WSP provided the final design of the Phase 2 structure while Phase 1 was under construction and completed final detailed plans six months ahead of schedule. This allowed a seamless transition between the Phase 1 and Phase 2 construction contracts.
Single-tower cable-stayed structures are rare, and this bridge was made even more exceptional by the unique, unbalanced span arrangement that accommodates environmental and local roadway constraints below. The Phase 2 cable-stayed structure has a front span of 609 ft and the back span is 343 ft. The single tower support is located on the Queens side of Newtown Creek and extends to a height of 287 ft. This is just below the maximum height permitted, due to its proximity to the LaGuardia Airport approach pattern.
A concrete and steel counterweight was designed and constructed at the end of the back span to balance the large weight differential due to the differing lengths. On a cable-stayed structure, high wind or rain events can result in high amplitude vibrations of the cables. Internal hydraulic dampers were installed at each cable to absorb this energy and dampen the vibration effects, which minimizes the motion of the cable, reduces fatigue effects, and ensures the stability of the structure.
The precast concrete deck is supported by steel floor beams and edge girders. The 56 stay cables, placed at various angles to connect the edge girder to the two vertical legs of the pylon, comprise nearly 1 million linear ft of steel strands. To help reduce future maintenance requirements and provide a 100-year service life, the structural steel was metalized. In addition, a 1-in.-thick polyester polymer concrete overlay was applied over the precast deck panels to protect against chloride infiltration and premature deck deterioration. Stainless steel rebar in the deck and concrete cap beams under expansion joints helps protect against future concrete spalling and cracking.
