Tappan Zee Constructors President Terry Towle.
With a lifting capacity of 1,900 tons, the I Lift NY crane is one of the largest floating cranes of its kind.
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The key challenge is working over one of the widest points of the Hudson River, covering a distance of 3.1 miles between Rockland and Westchester Counties. Working over the river is more challenging than working on land, so we prepare many bridge elements — including the structural steel sections, rebar cages, and pier caps — at off-site locations. We have a staging yard at Tomkins Cove in Rockland County and an even larger, 16-acre, location at the Port of Coeymans in Albany County. Both of these sites are located alongside the Hudson, allowing us to easily barge the materials directly to the project site for swift installation.
Coeymans has been crucial to the success of the project, as the staging area allows us to take large steel girders and combine them into even larger sections. Assembling the sections on land in a controlled environment helps us maintain a high degree of safety, quality, and efficiency. The sections are installed with the project’s largest crane, known as I Lift NY. It’s one of the largest floating cranes of its kind, and its 1,900-ton lifting capacity helps us raise large sections of the bridge relatively quickly.
What are some unexpected issues you encountered in the design/build process?
We gathered a great deal of data about the areas both near and beneath the river before starting construction…but there are always surprises. Take, for example, the weather. We could not have predicted that we would live through two of the toughest winters in recent memory at the beginning of the project. We had to accelerate efforts when the weather warmed, to make up for the time we lost during those unusually harsh winters.
What are some of the most meaningful milestones achieved during construction thus far?
There have been so many: The completion of the project’s eight main-span towers, which stand 419 feet above the Hudson River. Also, the beginning of stay-cable installation on the main span last summer [the first stay-cable bridge on the Hudson]. Approximately 90 percent of steel support structures have been completed, including the fabrication and placement of 126 girder assemblies. The last foundation pile was recently driven into the Hudson River and more than 1,000 piles have been installed to date. Also, more than 3,000 road-deck panels — each 12-feet long, ranging between 22- and 45-feet wide and more than 10-inches thick — have been installed. This accounts for 3.4 miles of road deck for the approaches to the bridge.
Working on the 3.1-mile span that separates Westchester and Rockland is one of the project’s greatest challenges.
Technology – including a traffic-monitoring system and cashless tolling — seems to play a large role in this new bridge. What are some of the benefits of these features?
This is going to be a state-of-the-art bridge, and the technology involved will make it better for drivers and easier for the owner to monitor and maintain. The shift to cashless tolling improves traffic flow and air quality because vehicles will no longer idle in toll-collection lines.
Intelligent Transportation Systems will improve traffic safety and mobility, by monitoring conditions on the twin-span crossing and automatically informing Thruway staff of any disruptions. This will allow for quick and concise communication with motorists through the bridge’s overhead electronic signs and similar signage on its Westchester and Rockland landings.
The new bridge will also feature a technologically advanced Structural Health Monitoring System. The tool will measure and monitor the structural behavior of the bridge under everyday conditions, such as traffic and temperature changes, and will also help the Thruway Authority efficiently schedule routine- and preventative-maintenance work, using the data it collects.
Currently, the bridge is on track to be completed on time and on budget. How have you managed to avoid time and cost pitfalls?
Of course, on a project like this, keeping on time and on budget [are two] of our most important goals. We utilize the design/build process, which incentivizes the private sector to be creative on approaches that speed construction time and reduce cost. The State also gets the assurance of cost certainty. I meet regularly with Project Director Jamey Barbas, who works for the Thruway Authority, to discuss key issues and schedules. We have also been fortunate to attract an incredibly dedicated and hard-working group of project managers and engineers, and a highly skilled workforce here in the Hudson Valley.