Engineering History

Progress continues apace on the new bridge’s main span. Photo: Courtesy of the New York State Thruway Authority

Progress continues apace on the new bridge’s main span. Photo: Courtesy of the New York State Thruway Authority

by Rebecca Rudell

Published March 7, 2017

It will take 220 million pounds of steel, 300,000 cubic yards of concrete and more than 5,800 workers to build the New NY Bridge—and seven UB alumni are helping to bring it all together. 

“We are earning a reputation for putting out well-qualified students who can jump into the role of bridge engineer right out of school.”
Jerome O'Connor, Executive Director
Institute of Bridge Engineering

“Every day is an adventure.”

It’s what each UB alumnus said—and, we imagine, what every one of the thousands of men and women working on the New NY Bridge project would say as well. The sheer magnitude of the project (it’s a 3.1-mile twin-span over a deep water channel) and the historic location (where Rockefellers played and the Headless Horseman was “born”) are just two of the factors that make it a fascinating undertaking. Add in the fact that there’s a 328-foot crane floating on the Hudson that can lift 12 Statues of Liberty, and you pretty much know you’re involved with something special.

The $3.98 billion bridge project officially began in 2011, when legislation was enacted and labor agreements signed, but its history goes back even further. The original Tappan Zee Bridge, which spans the Hudson River and touches down in Tarrytown, N.Y., and South Nyack, N.Y., opened in 1955. Built during a materials shortage brought on by the Korean War, it has required hundreds of millions of dollars to be spent over the years in maintenance and repair. Even so, some people are amazed it’s still standing. A government official dubbed it the “hold-your-breath bridge.”

So, in 1999, discussions to replace the bridge began. Those “discussions” carried on for more than a decade. Finally, Gov. Andrew M. Cuomo pushed the project forward, making the new bridge a reality. Ground broke—or more correctly, was dredged—in August 2013. The governor had a checklist for the bridge. It had to 1) be aesthetically pleasing, 2) use the design-build process to keep the project on time and on schedule (see below), and 3) be the most open, transparent project in state history. (As for No. 3, check out NewNYBridge.com. You’ll find everything you’d ever want to know about bridge construction.)

The new design is a twin-span, cable-stayed bridge with eight 419-foot towers that soar majestically above the Hudson. The largest bridge project in New York State history, it includes cutting-edge design features (like a monitoring system that can detect when winds are too strong for large trucks), and uses construction equipment that allows the steel and concrete towers to be built right on the river.

We spoke to the seven alumni working on the project about what makes the bridge unique, how they contribute to the team and why they enjoy coming to work every day. Whether they provide steel quality assurance or sign the paychecks, all of them said they are awed by the colossal scale of the project, the talent involved in the design and construction, and the fact that each of them is playing a part in New York State history.

Bridge Players

New York State Thruway Authority (NYSTA):
Owner of the Tappan Zee Bridge and the New NY Bridge Project

New York State Department of Transportation (NYSDOT):
State agency providing technical and management support to NYSTA

Tappan Zee Constructors (TZC):
Design-builders; hired by NYSTA to design and construct the New NY Bridge

HNTB:
Owner’s engineer; consulting firm hired by NYSTA to provide technical oversight of the project

Arup:
Subcontractor hired by HNTB to provide a broad range of services

Greenman-Pedersen:
Subcontractor leading TZC’s independent quality-assurance program

There are hundreds of other companies (more than 680 in New York State alone) working with the NYSTA to complete the New NY Bridge.

Sleek & Strong

The project’s first stay cable is raised to its anchor point. Photo: Courtesy of the New York State Thruway Authority

The project’s first stay cable is raised to its anchor point. Photo: Courtesy of the New York State Thruway Authority

The New NY Bridge will be the first cable-stayed bridge over the Hudson River and will be one of the longest bridges of its kind in the United States. Bridges stay up because of two forces: compression and tension. The weight of the main span deck is transmitted to the towers—through the cables—and, ultimately, to the bedrock below.

  • There will be 192 stay cables on the main span, with 12 on either side of each tower.
  • Stay cables will range from 190 feet to 625 feet.
  • If laid end to end, the length of the cables would equal 14 miles. The metal strands within the cables would extend 700 miles.

Rise and Climb

Self-climbing jump forms were used to build the iconic main span towers. Photo: Courtesy of the New York State Thruway Authority

Self-climbing jump forms were used to build the iconic main span towers. Photo: Courtesy of the New York State Thruway Authority

Between summer 2015 and winter 2016, eight bright, blue boxes could be seen moving up the bridge’s slender, concrete towers as they were built. Called “jump forms,” the ingenious 650-square-foot workspaces were used to create the towers in situ.

Here’s how they work:

How the jump forms work.
  1. Internal and external steel frames are secured to a tower segment.
  2. The external frame is raised up—or “jumps”—creating a safe space for the bridge crew to work inside.
  3. Crew members install steel reinforcements and the internal frame is moved up.
  4. The internal frame, which serves as a casting mold, is filled with concrete.
  5. Once the concrete has cured, a series of rails is lifted to the next level and the process starts again.

Always on Alert

Everything is designed to be “smart” these days, and the New NY Bridge is no exception. Part of the design includes a structural health monitoring system (SHMS), which will be the most comprehensive system of its kind in the country.

Sensors and other instrumentation will measure and monitor the structural behavior of the bridge as it undergoes daily traffic loads and temperature changes—and even during extreme circumstances like hurricanes and earthquakes. The SHMS also will allow bridge officials to program routine and preventive maintenance activities, and alert them if any damage has occurred.

An ironworker helps connect a seismic isolation bearing to the steel girder assembly. Photo: Courtesy of the New York State Thruway Authority

An ironworker helps connect a seismic isolation bearing to the steel girder assembly. Photo: Courtesy of the New York State Thruway Authority

Bird's Eye View

“Painters Point” is the third of six belvederes on the pedestrian and bike path. Its design reflects the arts and culture of the Hudson Valley region. Rendering: Courtesy of the New York State Thruway Authority

“Painters Point” is the third of six belvederes on the pedestrian and bike path. Its design reflects the arts and culture of the Hudson Valley region. Rendering: Courtesy of the New York State Thruway Authority

The New NY Bridge isn’t just for vehicles. Six belvederes, aka overlooks, will be situated at strategic locations across the span for pedestrians and bicyclists to take advantage of. Each belvedere has its own specially designed seating, shade structures and interpretive panels, offering a place to learn a bit about Hudson River history and take in the million-dollar views.

Preparing the Bridge Brigade of the Future

IBE students visit the old Tappan Zee Bridge. Photo: Courtesy of IBE

IBE students visit the old Tappan Zee Bridge. Photo: Courtesy of IBE

America’s infrastructure is old. Really old. In major cities across the country, we still depend on pre-Civil War water mains and railway tracks. And many bridges built in the 1950s during the construction of the interstate highway system, like the Tappan Zee, no longer meet today’s needs.

Aside from the fact that hundreds of projects languish on a lengthy backlog awaiting government approval, and that the cost of repair or replacement runs into the billions, there’s another issue holding back progress: The professional workforce needed to manage these jobs is retiring. Yes, talented civil engineers are graduating into the workforce every year, but many lack the professional skills needed to lead these complex endeavors.

In 2013, after years of meetings and gathering input from fellow engineers, George Lee, SUNY Distinguished Professor Emeritus, established UB’s Institute of Bridge Engineering (IBE) to help address this dire situation.

While other universities offer courses in bridge engineering, UB’s IBE is the only program of its kind in the country, where students can earn a Master of Science degree that focuses specifically on bridge engineering. And it’s already making a difference. “We are earning a reputation for putting out well-qualified students who can jump into the role of bridge engineer right out of school,” says Jerome O’Connor, the IBE’s executive director.

The IBE program has three focus areas: education, research and professional engagement. Students take core technical courses, like steel bridge design and earthquake engineering, but they also perform studies of actual bridges, for example, using analytical software to determine whether standing bridges require repair or need to be strengthened to support higher traffic loads.

Students also benefit from interaction with practicing engineers, like Dan D’Angelo and Tim Kaiser. D’Angelo has served on the advisory board of the IBE since 2014, contributing to the curriculum, mentoring students and evaluating projects. Kaiser, an alumnus of the program who joined the board a few months ago, describes the IBE as a community, not just for students to interact with engineers, but also for pros to come together and expand their knowledge.

Indeed, in addition to granting degrees to students, the program offers online courses and seminars as continuing education for professionals—crucial in a field where technologies are being developed all the time. “The IBE,” Kaiser says, “provides an opportunity for experts to share their experiences and really accelerate the profession.”