Built to Last 100 Years.
“A galvanized coating is a mechanical coating, so it bonds to the rebar. It’s a more durable coating. Zinc is a metal that does not expand when it deteriorates, which can lead to spalling. Since 1996, all of our construction projects—bridge replacements, new bridges, rehabilitations, sub-structure repairs, highway barriers, anything with reinforced concrete—has been galvanized.”
Paul Provost, Structural Engineer, NYSTA
The new bridge was built just north of the exisiting Tappan Zee Bridge, which was completed in 1955. After less than 60 years, harsh environmental conditions and increasing bridge traffic had taken a heavy toll, particularly on the bridge deck, leading the New York State Thruway Authority (NYSTA) to conclude in 2013 that it would be cheaper to replace the old bridge than continue to maintain it.
A primary contributor to the old bridge’s deterioration was corrosion of the steel rebar used in the concrete bridge decks. So the engineering and construction firms hired to build the new bridge first considered using stainless steel rebar, at a cost of around $3.70 per pound. But that’s when the American Galvanizers Association stepped in and made a presentation that changed the entire trajectory of the project.
Hot-dip galvanized rebar could also deliver a 100-year bridge, but at a cost of around sixty-five cents a pound. Bridge scuppers, walkways, railings, signposts and even the 700 miles of metal strand stay cables providing essential support to the bridge could all be made from galvanized steel. Not only was galvanizing more cost-effective, but it also eliminated ongoing maintenance costs associated with traditional paint options.
A project of this size (118 million pounds of galvanized rebar alone) requires a massive coordinated effort by the industry. Two Valmont® Coatings companies, American Galvanizing and Empire Galvanizing, supplied 50 tons of galvanized rebar for the project, along with galvanized steel bridge scuppers, signposts and walkway railings. Kettle capacity and proximity to steel suppliers played a major role in securing their bids.
Built in 32 months, at a cost of $3.98 billion, the new bridge was completed in 2018. Its clean, open design reflects the open feeling of the Hudson River Valley itself, where it will serve residents and commuters for many decades to come.