IABMAS 2018 Conference
(International Association for Bridge Maintenance and Safety, 2018 Conference), Melbourne 9-13 July 2018
The Whipple Bowstring Truss bridge (patented in 1841), was the first bridge truss design in the world that used scientific principles, by Squire Whipple, who published them in the 1847 book: A Work on Bridge Building. Designed for the Enlarged Erie Canal in New York State (1836-1862), hundreds of Whipple Bowstring Truss bridges were built for the canal and other waterways. One such bridge was the Shaw Bridge, built in 1870, for the New York City to Albany Post Road over the Claverack Creek, in the idyllic Hudson Valley. This bridge is one of only eight of the vintage Whipple Bowstring Truss bridges left, the lone one in its original location and the only double span. It clearly exemplifies the robust original design, including the use of cast iron for compression members, wrought iron for tension members, and a wooden deck that could be replaced without affecting the strength of the bridge. Since the Shaw Bridge is uniquely in its original location, it also has its original masonry abutments and pier. Despite being used for 120 years and closed for over 25 years, the bridge is in remarkably good condition, which speaks well for its original design and materials (19th century cast and wrought iron being more rust resistant than most modern steel). Whipple's importance cannot be overstated. Besides clearly documenting theoretical principles for bridge design for the first time, he promoted the use of prefabricated components, life-cycle costing, and was important for the Enlarged Erie Canal and early railway industry, helping make New York City become a world leader. The bridge is clearly eligible for Historic Civil Engineering Landmark status and this paper argues it is a World Heritage Bridge candidate. The meticulous restoration of the Shaw Bridge to its original specifications (see Figure 2) will be a fitting tribute to the genius of Squire Whipple.
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