Tappan Zee bridge in Westchester County, New York; Tappan Zee bridge in Westchester County, New York;

Tappan Zee Bridge I-287 Corridor, New York

Helping New York State plan the future of a critical transportation corridor

Arup helped New York State plan the future of a critical transportation corridor linking New York City to New Jersey and beyond.

The Tappan Zee Bridge forms part of I-287, a 30-mile thruway linking New Jersey to Westchester County, immediately north of Manhattan. Future development of the metropolitan area north of New York is heavily dependent on the outcome of this project. As the region’s primary east-west crossing, the route has been a catalyst for regional development since the 1950's.

The bridge carries approximately 135,000 vehicles a day and is expected to grow by over 40,000 by 2025. The traffic far exceeded the flow anticipated when the bridge first opened in 1956. 

The project is the first major transportation design/build project in New York State.

The options that were under consideration for the future of the Thruway throughout the project included rehabilitating the current bridge, replacing it either with or without new commuter rail and/or bus rapid transit, and creating new tunnels under the Hudson River. 

Comprehensive analysis for a major thoroughfare

Arup investigated numerous aspects of the corridor, including vulnerability, environmental concerns, risk and security. Our services included transportation planning; bridge and tunnel design; civil, structural, mechanical, electrical, geotechnical, highway, rail and seismic engineering; and security, cost, fire/life safety consulting; and transaction advice. We were responsible for bridge inspection and testing; fatigue and seismic analyses; vulnerability and risk assessments; security; and rehabilitation cost estimation.

Our comprehensive threat and risk assessment covered natural, accidental and deliberate threats. We calculated the probability and consequence of each threat to prioritize risks, then identified structural, operational and security countermeasures. Our security design team provided a security audit to identify pre-engineering design requirements (such as fencing and lighting) for both electronic and physical security. We also facilitated a risk comparison exercise with the client and developed a risk/cost decision model.

Building consensus

As the engineering support consultant, Arup also collaborated with stakeholders and the public to help achieve consensus by providing input on technical issues. We facilitated an extensive public outreach effort, including meetings and workshops with local stakeholders and interest groups.

Based on information gained during this process, Arup’s team developed the preliminary design and output specifications for the draft environmental impact statement.

Technical advisory support for procurement

Arup provided integrated technical advisory support during the procurement process, incorporating constructability reviews with both qualitative and quantitative assessments of key project risks and mitigants. We advised on the development of a design-build procurement structure tailored to the owner’s resources and objectives, then managed the process to deliver commercial and technical expertise on a wide range of tasks, such as the establishment of an evaluation plan and selection criteria. This fast-tracked procurement resulted in contract award only nine months after the RFQ release. 

Leaving a legacy

The client has been extremely pleased with our contributions throughout the project. As Karen Rae of the New York State Governor’s office said in early 2012, “The team has worked hard to understand the goals and provide new solutions . . .  this project will be a legacy among projects in the US.”