Verrazano-Narrows Bridge, New York, USA
Eliminator® provides long term protection on landmark New York 'Superstructure' bridge.
Built in the late 1950s, the Verrazano-Narrows Bridge is an imposing sight in New York Harbour. The longest span bridge in the Americas, it connects Staten Island and Brooklyn across the Narrows body of water. A double-decked suspension bridge, it is 7,176m long and 198m high – to allow ship traffic to pass below into the Port of New York and New Jersey.
In 2008, 190,000 vehicles were recorded passing over the bridge every day – making it a key route on the East Coast. The result of the large volume of traffic and heavy use is that the 50-year old upper level deck required replacement, to make way for a lighter weight, more durable steel orthotropic deck. The refurbishment works also involved the creation of a seventh lane – to be used as a bus and high occupancy vehicle (HOV) lane.
New York Metropolitan Transportation Authority (NYMTA)
- Verrazano-Narrows Bridge, New York
For the NYMTA, it was important that the new waterproofing solution could withstand extreme temperatures, as the bridge is subject to more extreme weather conditions than any other bridge in New York City, due to its proximity to the North Atlantic Ocean. This factor, combined with overall size of the bridge, means the bridge is often subjected to strong winds and snowstorms, sometimes resulting in its temporary closure. In fact, the roadway of the bridge is 12 feet lower in the summer than in the winter because of thermal expansion and contraction.
Several major factors influenced the choice of waterproofing. Most importantly, the specifiers were looking for a product with a proven track record on long-span bridge decks. Eliminator® was a key contender, having been used to protect the deck of many of the world’s biggest steel deck bridges. The system acts as a barrier across the entire expanse of the bridge deck and effectively prevents steel corrosion over the lifespan of the structure. In addition, the Eliminator system incorporates components that enhance the membrane’s bond to both the asphalt paving and the deck. This strong bond throughout allows the steel deck, waterproofing and paving to act as a composite – another key specification requirement. Given the dynamic forces constantly at work, this composite action is the key to long-term performance. Ease and speed of installation of the waterproofing system was another major factor.
The general contractor, Tutor Perini had a challenging construction schedule in one of the most densely populated cities in the world. They required a product that could be installed quickly and perform in both extremely high summer temperatures and extremely cold winter temperatures.
Disruption at all times was kept to a minimum thanks to Eliminator’s fast curing abilities – typically it cured within the hour and was durable enough at that time to withstand a heavy load – allowing other trades to access the site, facilitating contract progression. With the bridge are to be treated only closed for short periods of time, this was a crucial benefit to the project, enabling a rapid return to service.
The overall refurbishment work was carried out in stages. First, the old roadway decking was split into sections, which were then lifted up and out, one at a time, before being replaced with pre-fabricated deck panels. This method was engineered to cause minimal disruption to the traffic flow. Aside from the orthotropic deck waterproofing, each section of new roadway had to include other key elements: a finger joint installation, bridge barrier, bridge drainage system, asphalt overlay, new sign structures and upper and lower deck roadway lighting.
Waterproofing of the Verrazano-Narrows Bridge started in 2015 and the work was only carried out during restricted timeframes in order to create minimal disruption to traffic on the major bridge. As a key route between the New York City boroughs of Staten Island and Brooklyn, it was important to implement an efficient traffic system to keep the traffic moving and minimise disruption for commuters using the bridge. As a result, the work was carried out in restricted time frames, with lanes closed on both levels to carry out the refurbishment work.
To facilitate the short working windows, the deck was cut, removed and replaced in sections as part of a staged process. The 55,000m2 of new deck was prepared by shot blasting using metallic blast medium.
Spot adhesion tests were then conducted to assess the bond the waterproofing system would achieve to the deck. This is an extremely important step in the quality control process because, as previously stated, the bond to the deck is key to the long-term performance of the waterproofing.
Tom Carter, Vice President at Stirling Lloyd comments: “As a key route between Staten Island and Brooklyn, the waterproofing of the Verrazano-Narrows Bridge had to be carried out efficiently with the least disruption possible. The programme presented challenges due to extreme weather conditions, restricted working hours and shortpossession times. Eliminator’s credentials meant that it was a perfect solution for the project, as it offered the long-term protection that will ensure the Verrazano-Narrows Bridge stands the test of time and the peace of mind that the NYMTA sought.”
The challenging nature of this superstructure in New York made Stirling Lloyd’s Eliminator system the ideal solution for its long-term protection. Having made a significant investment in replacing the bridge deck - using a product that has protected so many long span steel bridge decks for over three decades in America - provides peace of mind that the country’s infrastructure is being protected for future generations.