The 3.1-mile-long Tappan Zee Bridge connects Rockland County to Westchester County in the Lower Hudson Valley, approximately 25 miles north of midtown Manhattan. It is a critical transportation link that serves an average of 138,000 vehicles per day.
The project has made extraordinary progress since construction operations began in 2013. More than 100,000 tons of pipe pile were driven, and with steel-reinforced foundations and concrete piers in place, the project recently completed installation of more than 200 enormous steel-blue plate girders that will support the road deck on the new twin-span bridge. The plate girders were pre-assembled into 200 units and weigh approximately 1,000 tons each. The steel superstructure supports the precast deck panels, installation of which is well under way. With a total of 110,000 tons of plate girders placed, 1,000-ton lifts by the Left Coast Lifter were commonplace.
Main pylon construction moved forward simultaneously, with concrete poured in place beneath jump forms. The main pylon crossbeams were precast directly on barges, sent directly to the project site, and placed with the Left Coast Lifter. The design height of the pylons is 419 feet.
Structural steel erection, stay cable installation, and precast deck panels are currently being constructed in a balanced cantilever sequence. Production is high; in one week the team is able to erect four stay cables plus two structural steel field sections, precast deck panels, rebar and concrete filler joints, and make tensioning adjustments. Once complete, there will be 96 stay cables, totaling 700 miles of metal strands.
The roadway deck consists of steel-reinforced concrete deck panels, each 12 feet long and varying from 22 to 45 feet wide. Almost 7,000 individual concrete road deck panels will be installed to complete the driving surface for the twin spans. The first crossing opened to traffic in mid-2017.