About the Project

About the Bridge

The three-mile Tappan Zee Bridge, located about 13 miles north of New York City, carries the New York State Thruway over the Hudson River, between Rockland and Westchester Counties. The structure serves as a lifeline between New York City and Upstate New York. The bridge carries about 140,000 vehicles every day, with volumes as high as 170,000 vehicles daily. When the bridge opened in 1955, it carried an average of 18,000 vehicles daily in the first year of its opening.

The bridge is one of the largest in the United States. It carries traffic across the Hudson River via three dedicated northbound and southbound lanes; a reversible lane is located along the center of the bridge providing a total of seven travel lanes. The lane is reversed twice daily using a moveable barrier to accommodate peak period traffic on weekdays.

An Act approved by the Legislature and signed by the Governor on February 28, 1956, officially named the structure the “Tappan Zee Bridge.” In pre-colonial days, this area was the home of the Tappan tribe of Native Americans; “zee” (sea) is the Dutch name for open expanse of water. In 1994, the bridge was rededicated as the Governor Malcolm Wilson Tappan Zee Bridge in honor of the former New York Governor. When first built, the bridge and its approaches originally cost $80.8 million.

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Existing Bridge Conditions

Construction began on the Tappan Zee Bridge in 1952; the bridge opened to traffic in December, 1955. It was designed with a capacity of 100,000 vehicles per day. It has carried considerably higher volumes of traffic than originally intended, peaking at 170,000 vehicles per day.

Over the past 50 years, the Authority has completed several significant projects to address structural deck and steel needs on the Tappan Zee Bridge, focusing primarily on the portion of the bridge east of the main span. Recent inspections and increased emergency maintenance repairs indicate that the structural deck and fascia structural steel on the western portion of the bridge have deteriorated. Other areas of deterioration are the concrete walkway, lighting and electrical systems.

The increased need for maintenance and repair of the bridge has also resulted in more frequent unscheduled lane closures, resulting in traffic delays for bridge travelers.

Is the bridge safe? Absolutely.

In addition to the Authority’s on-going $2.1 billion highway and bridge Capital Program, a very stringent and thorough Bridge Inspection Program (Program), as mandated by current Federal and State guidelines, is followed.  

The Special Inspection was completed in September 2009.  As a result of the inspection no deficiencies that would have resulted in additional structural flags were found.  Additionally, as of June 2010, there are no active structural flags on the bridge.  The General Recommendation (GR) remains as a 5.  The 2010 Biennial Inspection is currently underway and will be completed in late-November to mid- December of 2010. 

As part of the Program, the Tappan Zee under went a Biennial Inspection in November 2008, and received a CR of 3.71, up from a 2.96 in 2006; the Tappan Zee also received a General Recommendation (GR) of 5 during the 2008 Biennial Inspection and the 2009 Special/Interim Inspection, up from a 4 in 2006.  A GR places the most emphasis on the items of most   importance, the primary members.  A GR of “5” is defined as “Primary members and substructure are in good condition and do not need major repairs.”  It is important to note, no “red flags” were reported as a result of the 2008 Biennial Inspection. Meaning, there were no deficiencies requiring immediate response; supporting the Authority’s position that the structural integrity of the Tappan Zee remains intact and safe for motorists.

In addition to the 2010 Biennial Inspection, a Type 3 Diving Inspection will be performed in 2010.  The Type 3 Underwater Inspection will include the sampling/testing of several of the existing timber piles.  The results of these tests are expected to provide the Authority with information pertaining to wood/pile strength, wood decay if any, possible presence of Teredo ship worms and the overall condition of the timber pile foundations.  It is important to note the most recent Underwater Diving Inspection, completed in 2006, indicated that the timber piles are generally in good condition; no serious structural or scour deficiencies were noted. 

In addition to the Underwater Diving Inspections, “test boards” are collected on a monthly basis to check for the presence of marine borer (ship worm) activity in the waters adjacent to the Tappan Zee.  Recent test results have indicated there is no ship worm activity.

In addition to the Federal and State inspection guidelines, the Authority conducts hands-on inspections, has an 80-member crew dedicated to Tappan Zee Bridge maintenance and has installed sensors to monitor the stresses in wind bracings as related to wind speed and temperature.

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About the Deck Replacement

The May 2010-awarded contract will replace approximately 28 percent of the total concrete deck area on the Tappan Zee Bridge. When completed, approximately 96 percent of the original deck will have been replaced.  In addition to the deck replacement work, also under this contract the Authority will replace the movable barrier deployed to shift traffic flow during peak hours and install additional safety railings in a proactive effort to deter individuals in distress from jumping from the Bridge.

The previous deck replacement project (awarded in 2006) replaced approximately 40 percent of the entire deck, including the west end of the bridge and the main truss. In previous years, the Authority replaced half of the length of the center lane of the causeway and the entire east truss deck.

When complete in the Winter of 2012, the new deck, along with the other associated improvement work, will provide more reliable service, increase safety and add convenience for motorists using this vital east-west corridor. The deck replacement effort is part of the New York State Thruway Authority’s mission to provide safe, reliable service to its customers.

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