Stay cables are anchored to the interior of the concrete towers to support the weight of the main span roadway.
Following the completion of the iconic towers, the project’s main span team is still hard at work building the first cable-stayed crossing on the Hudson River.
Tappan Zee Constructors (TZC) continues to install the bridge’s stay cable system, which is nearly halfway complete six months after installation started.
The new bridge will utilize 192 stay cables to support the eastbound and westbound roadways on the main span. To date, more than 85 stay cables have been installed, with each cable containing numerous high-strength steel strands tightly packed in protective casings.
Crews first install the casing with a single steel strand in place. Once the material is secured to anchor points in the main span towers and the steel girders of the road deck, workers install additional strands through the casing, parallel to one another. The process continues until the casing is filled with strands. With multiple connections in every stay cable, the structure is given greater strength and flexibility. The main span team will install more than 700 miles of steel strands in total – about the distance from Tarrytown to Cincinnati – for the cable-stayed bridge.
“We’ve come a long way since the first cable was anchored back in July,” said Craig Cuppernell, P.E., TZC’s Project Manager for the Main Span. “We can walk across almost half of the main span now. It’s great to see our work pay off in a real way.”
Efforts are currently focused on completing the westbound stay cable system, with the final sections of steel roadway scheduled for installation in the coming months. These sections include cable anchor points that will allow the cables to be directly connected to the 419-foot main span towers.
Each side of the eight towers will have 12 pairs of stay cables, ranging in length from 190 to 623 feet. When the 2,230-foot main span is complete, the stay cable system will support a total of 74 million pounds of steel and concrete.
“It takes a team of dedicated, skilled individuals to build this kind of structure,” said Cuppernell. “And we’re proud of our work on the defining feature of the new bridge.”
The cable-stayed crossing will be the first of its kind on the Hudson River, with a design that differs greatly from the existing Tappan Zee Bridge. The cantilever design of the current bridge utilizes interconnecting steel trusses to collectively carry the weight of the main span. However, each of these trusses requires frequent and extensive maintenance, making the truss bridge design a less popular option in recent years.
The new bridge’s stay cable system is well-suited for long spans, offers a better cost benefit, and allows maintenance crews to monitor the integrity of the strands. Replacement strands can also be installed with minimal traffic disruption, without compromising the structural integrity of the crossing.
The new cable-stayed bridge is being built to last 100 years without requiring major repairs.
Learn more about the bridge’s design features and see the latest progress.
