The Cuomo Bridge A Landmark Rising Over the Hudson

The Governor Mario M. Cuomo Bridge is far more than a route connecting two sides of the Hudson River. The landmark structure has become an important part of the social and cultural character of the communities it serves, linking New York's Westchester and Rockland counties.

Situated fewer than 20 miles north of New York City, the new 3.1-mile twin-span cable-stayed bridge crosses one of the Hudson River's broadest sections. It was built to replace the aging Governor Malcolm Wilson Tappan Zee Bridge, and the final span of the new crossing was opened to traffic on September 8, 2018.

"We're proud of the team that delivered the Governor Mario M. Cuomo Bridge to New York," says Terence Easton, president of Fluor's infrastructure business line. "This is a landmark project that provides a vital link to the region and improves daily commerce."

The project was designed and constructed by Tappan Zee Constructors, or TZC, a consortium made up of several major design, engineering, and construction companies. The group included Fluor, American Bridge, Granite Construction, and Traylor Bros., together with HDR, Buckland & Taylor, URS, VSL, and GZA.

With a total cost of $3.98 billion, the project represents one of the largest single design-build transportation contracts ever awarded in the United States. It also became the largest bridge project in New York State's history.

A Sensible Solution

Each of the bridge's two spans carries four lanes of traffic and includes dedicated space for disabled vehicles, emergency services, and buses. The twin-span design was also developed with future mass transportation in mind, allowing for potential commuter rail service. A modern traffic-monitoring system further improves the management of traffic across the crossing.

A shared pathway for pedestrians and cyclists is another major component of the new bridge, creating a transportation and recreational connection for people who are not traveling by car.

The original Tappan Zee Bridge had itself become an iconic Hudson River structure, but after decades of service it had reached the end of its practical lifespan. The bridge opened in 1955 and remained an essential transportation route for local residents, commuters, travelers, and commercial vehicles until it was retired on October 6, 2017.

By 2016, traffic had increased to approximately 140,000 vehicles every day, considerably exceeding the volume the Tappan Zee had originally been designed to accommodate. Congestion, narrow traffic lanes, and the absence of emergency shoulders created potentially dangerous conditions.

The old bridge recorded roughly twice the average accident rate per mile compared with the rest of the 570-mile New York State Thruway system. In the years before its replacement, hundreds of millions of dollars were spent keeping the aging structure operational. Continuing to maintain it would have cost nearly as much as constructing a new bridge, while doing little to solve the existing traffic problems.

After almost 62 years of service, the New York State Thruway Authority finally retired the original bridge.

The new Governor Mario M. Cuomo Bridge has become a lasting symbol of New York's Hudson Valley. Its distinctive appearance and enormous scale make it a visually prominent landmark, while its twin cable-stayed spans rank among the widest structures of their type worldwide.

Design Features

The Governor Mario M. Cuomo Bridge was engineered for a service life of more than 100 years without requiring major structural repairs. In addition to its long-term durability, the bridge was designed to serve as a recognizable visual landmark and is among the world's widest cable-stayed bridges of its kind.

A cable-stayed bridge supports its roadway with straight cables that connect the deck directly to the tops of towers. During construction, the towers are erected first, after which sections of the deck and the supporting cables are installed progressively.

The bridge's principal span provides its most recognizable visual feature. Its cable-stayed main structure is supported by eight towers, each rising 419 feet above the river. The towers lean outward at an angle of five degrees and feature a streamlined chamfered form.

The angled tower configuration was selected by the project's Visual Quality Panel, which was composed primarily of residents from Rockland and Westchester counties. Tilting the towers outward gives the bridge a distinctive appearance while removing the need for an upper transverse strut, the structural member commonly placed between paired towers.

As a result, travelers crossing the bridge experience a more open view of the Hudson Valley. The eight towers support a total of 192 stay cables containing approximately 4,900 miles of steel strands. The design combines a clean visual appearance with strong structural support, improved safety characteristics, and an open feeling across the river.

The shared pedestrian and bicycle path will contain six overlooks. Each resting area is intended to reflect elements of the Lower Hudson Valley's history and culture. The pathway also establishes a new non-motorized transportation connection between the surrounding communities while providing a recreational feature that had previously been unavailable in Rockland and Westchester.

Building information modeling, commonly known as BIM, played a major role in the bridge's design and construction. HDR used BIM software to create a detailed digital representation of the new crossing and store its information in a secure database before physical construction began.

As work progressed, designers were able to refine the plans and respond to unexpected challenges with the help of the digital model. The BIM system is expected to remain useful for maintenance teams for many decades after completion. Containing nearly one million individual data points, the model covers not only the bridge but also associated facilities and the approaches and landings.

Construction Challenges

One of the most demanding engineering tasks involved building the enormous main-span pile caps that form the foundations for the 419-foot towers supporting the twin spans.

A conventional approach would normally involve constructing a cofferdam, sealing off a large section of the river so that workers could operate inside a dry enclosure. However, the Hudson River presented several difficult conditions. At the construction site, the river is more than 40 feet deep, experiences tides of up to six feet, and carries strong currents through its navigation channel.

Combined with the enormous dimensions of the pile caps, these conditions made a traditional cofferdam solution impractical. TZC therefore needed to develop a different method.

The project team turned to VSL, a company with extensive experience developing specialized solutions for complex construction problems. VSL engineers created a system using 34 synchronized hydraulic jacks capable of carefully lowering empty "tubs" surrounding the pile caps. These tubs served as the shells around which the final foundation structures were constructed.

In 2014, the tubs were lowered into the Hudson River with remarkable accuracy. Constructed from concrete slabs and steel plates, each structure weighed hundreds of tons and stretched more than 360 feet in length.

One VSL engineer described the challenge by noting that although the company had performed similar operations hundreds of times around the world, it had never attempted one involving a structure as large as a football field.

Engineers spent months working through every stage of the process and developing specialized supports capable of keeping each section of the tubs level. The 34 hydraulic jacks were attached to the structures and connected to more than a dozen steel cable strands apiece.

The cables ran through the tubs and passed through the hydraulic jacks. The system operated somewhat like a caterpillar climbing a branch. The jacks pulled and gripped the cables, gradually extending them and lowering the massive structures into the river by only a few inches at a time.

A central computer coordinated the hydraulic jacks so they could operate simultaneously. Sensors continuously measured the position of every jack with accuracy down to a fraction of an inch. If one jack moved out of synchronization with the others, the entire operation was designed to stop automatically.

The movement was so slow that it was almost impossible to see with the naked eye. Lowering each 14-foot-high tub by nine feet required approximately eight hours.

After the tubs had been secured in their final positions, water remaining inside their approximately 360-by-60-foot working areas was pumped out. Construction continued through the spring of 2015, when the foundation caps were reinforced with galvanized steel cages and filled with concrete.

During the first year or more of construction, much of the work took place beneath the waterline. By 2015, however, the emerging bridge had begun to reveal the distinctive shape that would eventually become an iconic part of the Hudson Valley.

The project site eventually contained thousands of workers and an extensive fleet of roughly 130 floating cranes, barges, tugboats, and other vessels. TZC progressed with the construction of the bridge foundations and the growing sequence of piers across the Hudson River.

While freezing winter conditions periodically restricted construction activity on the river, numerous offsite manufacturing facilities were working intensively to produce components for the twin-span bridge.

Every major component of the new bridge was manufactured within the United States. Many pieces were fabricated as large sections away from the construction site and then transported to the Hudson River. This prefabrication strategy made final assembly and installation more efficient.

Precast concrete sections were produced in Schuylerville, New York, as well as at facilities in Pennsylvania and Virginia. Steel reinforcement cages were assembled in Rockland County.

The bridge's enormous steel girders were manufactured in Pennsylvania. Measuring approximately 12 feet high and 350 feet long, the girders were assembled at the project's Port of Coeymans facility south of Albany before being transported by barge to the construction site.

These massive girders function as the structural connection between the bridge piers while also supporting the roadway. Some of the largest pieces weighed approximately 1,100 tons, requiring specialized lifting equipment.

That task was handled by a massive floating crane that arrived at the project site in autumn 2014. The crane was nicknamed "I Lift NY" and was owned by TZC. Its official U.S. Coast Guard registration name was "Left Coast Lifter."

Recognized as one of the world's largest floating cranes, I Lift NY has a 328-foot boom, making it taller than 30 stories.

The super crane became a crucial part of the project. Its enormous lifting capacity helped shorten the construction schedule by months compared with initial projections and reduced project expenses by more than $1 billion.

I Lift NY was used to install the huge pile caps, steel girders, and deck sections of the new bridge. Later, the same crane was used during the dismantling of the old Tappan Zee Bridge, allowing sections weighing as much as 1,000 tons to be removed in single lifts.

This approach made demolition considerably more efficient than using conventional cranes. Without I Lift NY, the project would have required a substantially different construction strategy or an alternative foundation design.

Preserving the Environment

Environmental protection was an important consideration throughout construction. Extensive procedures were introduced to monitor and limit the project's effects on the surrounding communities and the natural environment.

The Lower Hudson Valley supports a diverse range of wildlife, including endangered peregrine falcons, Indiana bats, and Atlantic sturgeon. Because of this ecological diversity, a major infrastructure project of this scale required an extensive permitting and environmental review process.

The project team coordinated closely with the National Marine Fisheries Service, the New York State Department of Environmental Conservation, and other regulatory agencies to reduce the bridge's environmental impact.

Among the measures implemented were construction equipment and techniques that required less dredging, the use of smaller pilings, greater adoption of clean-fuel technology, and various steps intended to reduce construction noise and safeguard wildlife.

Materials from the demolition of the former Tappan Zee Bridge were also given new uses. Concrete and other clean recycled materials from the old structure are being used to help create six artificial reefs off Long Island.

The completed twin-span bridge is remarkable not only because of its scale and distinctive design but also because of the complexity involved in delivering the project. Construction created employment for thousands of New Yorkers, contributed to economic activity, and produced a major new transportation link designed to serve the surrounding communities for more than a century.