Global construction firm Skanksa recently won a $249 million from the Metropolitan Transportation Authority to dehumidify the cables on the Verrazzano-Narrows Bridge in New York City, the longest suspension bridge in the Americas.
Scheduled to be completed in the third quarter of 2029, Skanksa will design and install a main cable dehumidification system and acoustic monitoring system on all four of the bridge’s cables.
The project includes work on associated electrical and communication systems and five years of maintenance and monitoring on the newly installed systems. Skanksa will also facilitate internal inspections on main cable panels and replace key components including cable band bolts, main cable aerial obstruction lights and supports and messenger cables.
The Verrazzano-Narrows Bridge, which opened in 1964 as the longest suspension bridge in the world, connects Staten Island and Brooklyn and features a total length of 13,700 feet. It is now the 18th-longest such span in the world but still the longest in North and South America.
Dehumidification systems are designed to remove moisture from a bridge’s main cables to prevent corrosion and reduce the driver of hydrogen embrittlement in high strength steel wires, according to the American Society of Civil Engineers.
The first bridge in the U.S. to be equipped with a dehumidification system was the William Preston Lane Jr. Memorial (Bay) Bridge in Maryland in 2012. For that project, air-tight wraps were placed around the main cables that support the bridges’ decks, and injection and exhaust ports and dehumidification plants were installed. The system was equipped with remote sensors so its operations can be monitored.
The first dehumidification system in the world was placed in 1998 on the Akashi Kaikyo Bridge in Japan.
