The Tappan Zee Hudson River Crossing is being designed and built by Tappan Zee Constructors, LLC (TZC), a consortium of some of the world's best-known and most highly-regarded design, engineering and construction firms, including Fluor, American Bridge, Granite, and Traylor Bros., along with key design firms HDR, Buckland & Taylor, URS, and GZA. TZC is working closely on the project with a team of employees from the New York State Thruway Authority and the State Department of Transportation.
The 3.1 mile twin span cable-stayed bridge with angled main span towers is the single largest bridge construction project in New York’s history. The bridge will revitalize the existing Governor Malcolm Wilson Tappan Zee Bridge that connects Rockland County to Westchester County over the Hudson River.
Almost 6,000 steel-reinforced precast-concrete panels, each about 12 ft. long and up to 45 ft. wide, are being placed on the steel-girder system, supported by 68 football-field-sized pile caps, precast by Cape Charles, Virginia-based Bayshore Concrete Products. Crews placed the last of the 300-ton pile caps in the summer of 2015, reinforcing each cap with galvanized steel and sealing with up to 750 cu. yd. of concrete.
A milestone in the construction of the 61-year-old Tappan Zee Bridge replacement was achieved in February 2016 with the erection four 645-ton crossbeams. Using the famed Left Coast Lifter, which is one of the largest floating cranes in the world, the placement of the four crossbeams marks the midway point for the five-year project. The new work is located just north of the existing bridge. That bridge now carries 140,000 vehicles daily. When completed, the 96-foot-wide new northern structure will carry eight temporary lanes of traffic by the end of 2017. The north and south structures will each carry four lanes of traffic. Plus, the northern bridge will include a bicycling and pedestrian lane.
Work began on main span steel in June 2016, installing four large pre-assembled sections of steel, weighing nearly 340,000 pounds each, atop the main span crossbeams. In July 2016, TZC completed installation the first stay cables. Each side of the bridge's towers will require 12 pairs of stay cables to support the main span roadway, utilizing 700 miles of metal strands in total.
In December 2016, TZC announced the completion of all eight 419-foot concrete towers. The towers will support the 2,230-foot cable-stayed main span.