Gov. Andrew M. Cuomo yesterday announced the beginning of formal construction of the New NY Bridge to replace the Tappan Zee with installation of the first permanent piles that will make up the foundation of the new bridge. The bridge is scheduled to be completed in just under five years from the start of formal construction, making it one of the nation’s largest construction projects to be completed in such a short time.
“This week, we are putting shovels in the ground and starting formal construction on a new bridge to replace the Tappan Zee, the largest infrastructure project New York state has undertaken in decades,” Cuomo said. “After more than a decade of delay, New York state has moved this project forward at a dramatic pace while working with the community, involving the public and protecting the local environment. Once completed, drivers in Rockland, Westchester and surrounding areas will finally have a safer, less congested bridge that will include a walkway for pedestrians and bikers and accommodates future mass transit.”
When completed, the New NY Bridge will mean less congestion for motorists, with eight traffic lanes, four breakdown/emergency lanes and state-of-the-art traffic monitoring systems, as well as a dedicated commuter bus lane from the day it opens. Designed and constructed to be mass-transit-ready, the new crossing will be able to accommodate bus rapid transit, light rail or commuter rail. The twin-span bridge also will include a bike and pedestrian path.
- Dredging to prepare for bridge construction is ongoing until Nov. 1 and also will take place during August, September and October 2014;
- October 2013: Main span permanent pile installation begins;
- November 2013: Permanent pile installation begins for approaches;
- March 2014: Work begins on approach substructure;
- June 2014: Work begins on main span substructure;
- September 2014: Work begins for erection of superstructure;
- Late 2014/early 2015: Work begins on cable stay installation;
- Late 2016: Complete north span;
- December 2016: Relocate westbound traffic to new north span;
- February 2017: Relocate existing eastbound traffic to new north span;
- February 2017: Start demolition of existing bridge;
- Late 2017: Both spans complete;
- November 2017: Relocate eastbound traffic from new north span to new south span;
- April 2018: Physical completion of project; and
- July 2018: Final acceptance of project.
Steel piles created specifically for each pile location are brought to the construction site by a barge. Each pile is placed in several steps. First, a vibratory hammer shakes the pile, causing it to sink into the silty soil beneath the river to within a few feet of the water line. Then, a second pile is welded to the first to make one longer pile, and the weld is tested and inspected. The pile is then driven the remainder of the length needed to support the bridge, with an impact hammer equipped with a noise dampening shroud.
Once the steel pile is installed, steel reinforcement and concrete are placed in the pile. A pile cap is then added to the pile, consisting of a precast concrete form that is floated to the location. The main span tower pile caps will require approximately 6,000 cu yd of concrete.
The concrete used in the piles for the New NY Bridge will be made in a floating batch plant on-site, so that it will not need to be delivered by truck through local town and village streets.
After the pile caps are complete, the concrete piers are built from the water level upward. When they reach the proper height, a pier cap is constructed. The pier cap will support the structural steel that will in turn support the roadway. For the main span towers, the concrete continues until the towers have reached their full height: 419 ft above the river surface.
When the towers are complete, cables and roadway are constructed from the tower outward in both directions. As a segment of road is put in place, the associated cables are installed, concrete deck panels are installed and cast-in-place connecting strips are poured.