Fig. 2: With 14 lanes and 300,000 vehicles per day, the GWB is the
“ONCE-IN- A-LIFETIME:
T
busiest major crossing in the world. Photo Courtesy of Hugo Bouzon.
THE PORT AUTHORITY OF NEW YORK AND NEW JERSEY PLANS THE REPLACEMENT OF THE ORIGINAL ROEBLING SUSPENDER ROPES
ON THE GEORGE WASHINGTON BRIDGE” PART 2 BY: CLIFFORD W. ZINK
he Roebling workers who closed nearly 36 miles of 2 7/8 inch suspender ropes on their 80-Ton Rope Machine in Trenton, N.J., in 1929 would be amazed and proud to know that their product has been supporting the George Washington Bridge for 83 years
and counting (Fig. 1). And they would be pleased to know that new replacement ropes will replicate the original ones they made.
As noted in the first article on the GWB published in the May-June issue of WRE, the Port Authority of New York and New Jersey (PANYNJ) is planning to replace all of the GWB’s 296 suspender ropes and to clean and rehabilitate its main cables. In a recent conversation with PANYNJ engineers, Chief Engineer Peter Zipf said, “Tis will be an eight-year program for us, starting in 1914. It’s an intriguing, step by step process that will start with utility work and be completed by 2022.” Othmar Ammann, PANYNJ’s first Chief Engineer, designed the
Hudson River Bridge, as GWB was then called, in the late 1920s with four 36-inch main cables to support two decks, the upper deck to be completed first and the lower deck to be added about 25 years later when traffic projections indicated it would be needed. PANYNJ erected the lower deck in 1962, and now with 14 lanes and 300,000 vehicles a day, the GWB is the world’s busiest major crossing (Fig. 2). Robert Kumapley, PANYNJ”s Lead Structural Engineer for the
GWB Suspender Rope Replacement Project, explained that “Since the bridge opened in 1931, only 25 of the original suspender ropes have been replaced. 19 were replaced when the lower deck was added in 1961, and in 1999, six were replaced so that we could test them for their capacity.” When PANYNJ engineers began planning the replacement of the original
suspender ropes in 2009, they noted that the average age of replacement time on comparable bridges is 70 years. Similar Roebling suspender ropes on the Golden Gate Bridge were replaced in 1977 after 40 years of service. Bernard Yostpille, PANYNJ’s Chief Structural Engineer, noted that “Te fog and mist
24 JULY-AUGUST 2012 WIRE ROPE EXCHANGE
Fig. 1: More than 90 percent of the original 2 7/8 inch Roebling suspender ropes remain on the George Washington
Bridge after 83 years of service. Photo Courtesy Scott Schumaker.
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