The New NY Bridge
The New NY Bridge
The original bridge, which opened in 1955, has experienced numerous complications since it was constructed. Currently, more than 138,000 vehicles cross the bridge every day—far more than it was designed to handle. Traffic jams and delays are a regular occurrence, there are no lanes or shoulders for emergency or disabled vehicles, and over the past decade more than $750 million has been spent on bridge maintenance. The New NY Bridge will address these many issues, creating 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.
Owned by the state of New York, the New NY Bridge project is being designed and built by Tappan Zee Constructors, LLC (TZC), a consortium of some of the world's best-known design, engineering and construction firms, including Fluor, American Bridge, Granite, and Traylor Bros. TZC brought on Milwaukee-based Maxon Industries, Inc. (Maxon) to provide concrete material handling expertise and Putzmeister equipment for the job. After the initial planning stages, construction began in mid-2013 and the concrete production/placing barge was put into service in Summer 2014.
Floating Job Site
Because the project is literally rising out of the Hudson River, all of the materials and equipment being used are located on two barges, one working in from each shore. Each barge carries a backhoe for moving material, bins for raw material, a batch plant, Maxon remix surge hopper, a crane, and a Putzmeister stationary pump, placing boom and tower. Raw materials are barged to the site and offloaded onto the concrete production barge.
“The systems eliminate the need for over-the-road hauling of concrete from local concrete plants and ensure the best quality control,” explained Bill Maxon, president of Maxon. “The twin concrete systems were designed with speed and efficiency in mind.”
To allow concrete production to continue year round, Maxon supplied TZC with Heatec water heaters and chillers for each production barge. During winter months, when temperatures frequently fall below freezing, 25,000-gallon-capacity direct-fired tanks supply heated water to the concrete plants. Alternatively, to control the heat of hydration during placement of the large mass pours in summer, 80-ton water chillers provide super-cooled water from the tank to the concrete plant. Each chiller can produce 2,890 gallons per hour of 35°F (2°C) water with ambient air temperatures of 90°F (32°C).
A unique challenge when working on a waterway is that the crew has to be especially cautious to avoid any run off into the river. To avoid contamination, the Department of Natural Resources places strict restrictions on these types of projects. All waste from the concrete production, residual concrete and wash down water is being captured and disposed of back at shore.
Rising Out of the River
Creating the foundation for the bridge starts with the structural support pilings—approximately 1,000 steel tubes placed deep into the soil below the river. The next step is to fill the pilings with steel-reinforced concrete.
Maxon and Putzmeister’s Special Applications Business created the specialized pump and placing boom set-up. Located on each of the two barges are a Putzmeister BSA 2112 Trailer-Mounted Concrete Pump, Putzmeister MX 43/47 Placing Boom and Putzmeister DVH 5/2 Hydraulic Diversion Valve, which is being used for cleanout.
The concrete is delivered directly from the batch plant into an 18-cubic-yard Maxon Maxcrete Remix Surge Hopper that allows the plant to continue to produce concrete. The Maxcrete feeds the hopper of the BSA 2112 and is then pumped through the placing boom, which fills the pilings using its five-section Z-Fold boom and 138-foot (42m) horizontal reach.
“The size and versatility of the placing booms allow us to reach an entire pour without repositioning the barge, reducing the overall placing time,” said Wayne Dabrowski, project engineer for TZC. “The set-up has been successful at meeting the project’s unique demands.”
After the pilings are filled with concrete they are capped with more concrete using the placing boom. This creates the bases that will support the main 419-foot (128m) towers of the bridge. Once these bases are complete, the crew will use the production/placing barges to feed concrete to the forms as the towers extended above the water. After reaching 139 feet (42m) above the water level, the prefabricated road sections will begin to be installed as the towers continue to be built.
Next, the cables will be connected from the edge of the road deck to the angled towers as the bridge extends over the water, eventually creating the 1,200-foot (366m) main span. Additional pilings will be driven into the riverbed, and the smaller concrete support columns for the approaches also will be placed from the concrete production/placing barge.
100-Year Concrete Mix
Building a structure designed to endure high traffic with minimal structural maintenance over the course of 100 years is a significant undertaking. The project requires a specially designed, sticky mix with lots of additives that sets up quickly. The thickness of concrete mix makes it extremely difficult to pump, but the Putzmeister equipment has been up to the challenge.
“This project has been a huge undertaking,” said Dabrowski. “But we’ve been pleased with how the Putzmeister equipment has performed under such extreme demands.”
As the first span is completed, westbound traffic will be shifted the Tappan Zee Bridge to the New NY Bridge, with the eastbound traffic scheduled to shift upon completion of the second span in late 2017.