The Tappan Zee Hudson River Crossing is a critical commuter route between Westchester and Rockland counties and crosses the Hudson River at one of its widest points. This $3.1 billion, design-build project is currently being built by Tappan Zee Constructors (TZC), comprised of Fluor Corporation (30%), American Bridge Company (23 1/3%), Granite Construction (23 1/3%), and Traylor Bros., Inc. (23 1/3%). The project will replace the existing Governor Malcolm Wilson Tappan Zee Bridge, which has exceeded its originally-intended life span and traffic capacity. The new bridge includes two parallel 2,230 foot long cable-stayed structures with 1,200 foot midspans across the main navigation channel. Measuring 183 feet wide, the innovative superstructure will contain a total of eight general traffic lanes, four emergency lanes, a bike and pedestrian path and a state-of-the-art traffic monitoring system. Construction of the new Tappan Zee Bridge started in January 2013.
Working with a design team led by HDR, TZC engineered a steel superstructure to minimize overall weight, which in turn reduced foundation and dredging costs. The team also utilized friction pendulum bearings that reduced the stress required to be carried by the foundation system. The structure’s main span towers consist of four pairs of outward inclining cast in place concrete towers rising to 419 feet above water line. These towers were constructed using self-climbing forms.
In order to simplify the construction techniques dictated by the fluctuating water level of the Hudson River, TZC engineered a suspended pile cap forming system using precast soffit panels and a watertight form system to contain the 60’ x 360’ x 15’-6″ concrete in the pilecap. Additionally, TZC effectively managed the variable bedrock configuration and soil conditions in the Hudson River by utilizing pipe piles as the project standard, which optimized equipment and labor costs. While many of the 1,100 piles bear on the rock substrate, some reached depths of over 330 feet to develop the necessary skin friction without reaching bedrock.
In order to effectively and economically build the bridge, pre-assembly methods for major components were utilized. This required procurement, planning, design and construction of off-site yards, and the development of custom systems for land and water movement of bridge sections weighing up to 1,100 tons. TZC set up Coeymans Yard to fabricate girders and pre-install utilities, including water for fire safety, compressed air for tools, fiber optic communications lines, electrical lines for bridge lighting and components, and security and communications lines. The largest individual girders, 120 feet long and weighing almost 105 tons, were manufactured at shops in Pennsylvania, Virginia, and North Carolina, and are being delivered either by truck or barge to the Coeymans site. There, girders are then bolted together into assemblies consisting of two or three-girder lines up to 410 feet long. After fabrication, girders are loaded onto barges at the Port of Coeymans for a 20-hour trip down the river to the bridge site.
“I Lift NY” Super Crane
When girder segments arrive onsite, they are lifted onto the new superstructure using a floating crane called the Left Coast Lifter. Locally known as “I Lift NY”, this floating super crane has a barge that measures 384 feet long, 100 feet wide, and is more than 30 stories tall. The 1,900 ton capacity Left Coast Lifter serves as the unique tool that is able to erect the large prefabricated girder assemblies, and also has been used to erect the back span closure field sections on the westbound cable stayed bridge, precast concrete pilecap tubs, piercaps, tower struts.
A Brand New Bridge
The Tappan Zee Hudson River Crossing has already provided substantial improvement to the economy. With over 640 New York business subcontracts, the Project has created thousands of jobs on both the Hudson and off-site facilities. TZC is currently hard at work, delivering an innovative transportation system that will continue to improve the New York area.
- Owner: New York State Thruway Authority
- Location: New York, New York
- Project Value: $3.1B
- Structure Type: Cable-Stayed Bridge
- Procurement Model: Design-Build