New NY Bridge, United States of America
The New NY Bridge is a cable-stayed twin span bridge that will replace the Tappan Zee cantilever bridge, which has already exceeded its original designed capacity of 100,000 vehicles per day. The new bridge is being built north of the existing bridge, which was built in 1955.
The average daily traffic on the existing bridge is 138,000, while the peak traffic is approximately 170,000 cars per day. The bridge, traversing the Hudson River, carries the New York State Thruway and connects Rockland and Westchester counties.
Construction of the replacement bridge started in 2013 and the first span is scheduled to open in 2016, while full completion is expected in 2018. The estimated investment on the new bridge is $3.9bn. Pre-construction works for the project started in early 2013 and formal construction works started in October 2013.
The project is being administered by the New York State Thruway Authority. The design-build contractor is the Tappan Zee Constructors (TZC), which includes Fluor, American Bridge Company, Granite Construction, and Traylor Bros. The lead designer for the bridge is HDR.
Bridge replacement project background
Plans to replace the Tappan Zee bridge were first discussed in 1999. About $750m was spent in maintaining the existing bridge during the last decade.
A new plan was fast-tracked in October 2011 followed by the signing of several approvals and agreements. The bridge construction proposals were submitted in July 2012 and the design-build plan was finalised in December 2012. The final contract approval was granted in January 2013.
Design and construction of the New NY Bridge
The new cable-stayed twin span bridge is designed to last for 100 years without requiring major structural maintenance. The bridge, measuring approximately 4.9km, will feature two 365m cable-stayed main spans with outwardly inclined main span towers and 107m steel girder approach spans. The angled towers will rise about 419ft above the water and will feature a chamfered-top.
The new bridge will ease traffic congestion on the New York State Thruway by featuring eight general traffic lanes, four emergency lanes, a bicycle and pedestrian path on the northern span, a commuter bus lane, anti-climb fencing, and security cameras. It will also feature a new toll plaza including at least three highway-speed E-Z pass lanes. The bridge is being constructed to cater to future bus transit, light rail and commuter rail services as well.
The weight of the structure and the number and size of foundations will be minimised, and the dredge quantities will be reduced from 1.8million to less than one million cubic yards bringing down the environmental impacts, cost and construction duration. The bridge's design will reduce the number of piles required, while quieter vibration techniques for pile driving will be employed. The concrete used in the construction of the piles will be sourced from a floating batch plant on site.
The 400ft long Left Coast Lifter floating crane, now nicknamed as 'I Lift NY' super crane, which was earlier used to construct the suspension span on the San Francisco - Oakland Bridge, is expected to carry out the lifting works for the new bridge. The crane will later be used to demolish the existing bridge.
Financing the $3.9bn bridge replacement project
A low-interest (3.89 percent) federal loan amounting to $1.6bn for the New NY Bridge Project was granted by the U.S. Department of Transportation through its federal Transportation Infrastructure Finance and Innovation Act (TIFIA) programme.
Key players involved
Special inspections and materials testing for all the components of the bridge are being carried out by Tectonic.
Quality assurance activities for the project are being provided by Greenman-Pedersen and The LiRo Group. The project has so far generated more than 600 jobs and benefited more than 500 companies, which mostly comprise of local and regional companies.