Tappan Zee Bridge

New York, New York

Originally constructed in 1955, the three-mile long Tappan Zee bridge could no longer safely accommodate the 140,000 vehicles that travel the bridge each day. Heavy traffic and dangerously narrow lanes created unsafe driving conditions. As a result, the bridge had twice the average accident rate per mile as the rest of the 570-mile Thruway system. Rather than continue to spend hundreds of millions of dollars maintaining the bridge, the New York State Thruway Authority (NYSTA) undertook a massive $3.98 billion effort to design and construct a new bridge that will help to improve traffic conditions.

The new Tappan Zee bridge, recently named the Governor Mario M. Cuomo Bridge, is actually two “twin” bridges with a gap between the bridges designed to accommodate mass transit modes in the future, including bus rapid transit, light rail or commuter rail. The new main spans are cable-stayed, and the approach spans consist of steel girders with precast concrete deck slab units. The new bridge features four lanes in each direction with full inside and outside shoulders and a shared-use bicycle and pedestrian path on the north side of the bridge. The new bridge is designed for a 100-year service life.

Michael Baker provided design services for two, curved, continuous three-span bridge units of the twenty (20) approach units that make up the total replacement for the bridge. We also provided quality control and constructability reviews on the design of all twenty approach structure units.

Our team also was responsible for superstructure and substructure design of the approach unit and production of the final design drawings. All superstructure elements were designed to remain elastic during a 2,500-year return seismic event. The substructures were designed using precast tubs as formwork for pile caps to save the cost of cofferdam.

When fully open to traffic, the new bridge will significantly reduce traffic congestion, with eight general traffic lanes, four breakdown/emergency lanes, a bike and pedestrian path and state-of-the art traffic monitoring systems as well as space for dedicated mass transit in the future.

Standard of Excellence

“This project represents one of the largest single design-build projects in the United States. The final cable-stayed bridge, spanning the widest parts of the Hudson River, will be the largest bridge in the state and one of the widest cable-stayed structures in the world.”

Richard D.
Project Manager

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