Safeguarding the Hudson on New York’s Biggest Bridge Project
The $3.9 billion design-build replacement of the Tappan Zee Bridge was the largest bridge project in New York history and one of the biggest transportation design-build contracts ever awarded in the United States. The 3.1-mile twin cable-stayed span carries roughly 140,000 vehicles a day across one of the widest points of the Hudson River, connecting Tarrytown and Nyack. As a member of HNTB’s Owner’s Engineer team for the NYS Thruway Authority, our role on a project of this magnitude centered on something easy to overlook and impossible to get wrong: environmental compliance.
Our team prepared weekly Independent Overhead Environmental Compliance Monitor reports to NYSDEC and developed procedures for auditing compliance in construction noise and vibration, ensuring that a project of this scale met its environmental commitments as rigorously as its engineering milestones. Direct environmental compliance oversight of field staff kept accountability consistent across the corridor throughout construction.
Engineering Around an Ecosystem
A project spanning the Hudson River carries responsibility that extends well beyond the bridge deck. Our work included Peregrine Falcon nest monitoring and a suite of Net Conservation Benefit projects such as mapping of Hudson River shallows, a study of sturgeon foraging and movement, and by-catch outreach. Compensatory mitigation efforts included oyster restoration, secondary channel restoration, and habitat enhancements at Piermont Marsh, among other initiatives. On a project defined by its engineering ambition, this work ensured that the river and its ecosystems were treated as stakeholders, not just obstacles to build across.