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THE GEORGIA ENGINEER
The Hurricane Shoals area of North Georgia is located between the small towns of Maysville and Jefferson. The area once hosted the Hurricane Shoals Covered Bridge, which spanned the North Oconee River and served as one of the major links between the two small cities. Built in 1882 for $1,423 including materials, the bridge was constructed in a Town lattice style, named for Ithiel Town. The Town lattice truss configuration, which was a series of overlapping timber in a crisscross design that resembled a garden lattice, was an important development in bridge design, because it was used to support spans more than a hundred feet in length. Due to its versatility, the Town lattice truss became the most popular covered bridge design constructed. The Hurricane Shoals Bridge served as a major community landmark until 1979 when it was destroyed by arson. A group of local citizens formed The Tumbling Waters Society, which had as its mission to oversee the development of a park in an area adjacent to the Hurricane Shoals Covered Bridge. The group worked tirelessly for several years, investigating the possibility of rebuilding the bridge, raising money and generating interest in the local community for the project. Local county commissioner, Pat Bell, spearheaded an effort in December 2000, to obtain funding for bike paths in the park area, as well as the design and construction of a replacement covered bridge. These efforts resulting in the acquisition of federal transportation funding administered by the Georgia Department of Transportation. Ms. Bell and The Tumbling Waters Society contacted Dr. Cecil Hammond, a local covered bridge historian and professional engineer, who had recently retired from the University of Georgia. Dr. Hammond was asked to provide the historical context and conceptual design for the bridge. A supporter of historic preservation, Dr. Hammond reflected on the purpose of covered bridges. “Some argue that covered bridges were built initially to look like barns so that horses would not be afraid to enter them; however, many experts agree that the covered area of the bridge serves to protect the bridge structure from rotting.” "Whatever the case, I love old bridges; they are a part of our past. In fact, I wish more covered bridges would be built. I am truly honored to have been involved in such a worthwhile endeavor.” According to Ms. Bell, “The project would not have happened without Dr. Hammond. His inspiration encouraged me and the other bridge proponents to continue to work to ensure the bridge would be built.”
Working closely with Dr. Hammond, structural engineers from Armentrout Roebuck Matheny Consulting Group conducted research on the Town lattice truss system and its historical applications. The use of the bridge for pedestrian and bicycle traffic was also evaluated as well as the bridge’s potential use for carrying emergency vehicle loads. The first decision was to recreate the look and feel of the original stone abutments at both embankments with historically accurate stacked stone masonry. The actual structural design of the bridge then began in earnest with the engineers creating the structural steel skeleton for the bridge to support heavy truckloads across the 127-foot span. A modern structural support system, to be hidden within the lattice, was chosen over the historically accurate timber support system to ensure safety and versatility of the bridge to obtain state approval. The covered portion of the bridge was then designed by taking into account important building code requirements. The Tumbling Waters Society requested that as much of the upper portion of the bridge, including the framework, be comprised of wood material. The design presented a wood material column and beam framework with unobtrusive structural steel braces and connector plates in order to maintain the historic feel and aesthetics of the bridge while complying with modern code requirements. Photos of the original Hurricane Shoals Covered Bridge indicated that it contained one relatively small view opening at approximately mid span across the river. The Tumbling Waters Society wanted to have more openings for pedestrians to have better views of the river and the surrounding park as well as to provide natural light into the covered bridge space. Armentrout Roebuck Matheny Consulting Group created three large cased openings on each side of the bridge. During the entire design process, Armentrout Roebuck Matheny Consulting Group’s structural engineers and designers attempted to balance the desire for historic accuracy with the requirements of modern structural design. A paramount concern was the structure’s safety and compliance with the applicable building codes. In the final analysis, the engineers were able to strike a comfortable balance between the two sometimes-competing criteria.
“Dr. Hammond’s insight proved to be the cornerstone of the project,” said Armentrout Roebuck Matheny Consulting Group Principal David Roebuck. “His historical perspective allowed our engineers and the construction firm to recreate the bridge with as much historical accuracy as possible.”
The bridge presents an extraordinary example of history as well as practical purposes. According to Ms. Bell, “The bridge gives the County Commission the option to have one entrance into the park while providing a rare aesthetic value for park visitors.” “We cannot step into the future until we know and understand the past,” said Ms. Bell. “If we do not look to our past, our children will never know what to do in the present. This bridge offers us a glimpse of that past and perpetuates our community's values.” Bridge historical photograph provided by Dr. Cecil Hammond
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