Designated as a National Civil Engineering Landmark in 2001, the Bunker Hill Covered Bridge is the only remaining wooden example of the Improved Lattice Truss patented by Brigadier General Herman Haupt (1817-1905). With this distinction, it joined the Cape Hatteras Lighthouse, the Blue Ridge Parkway, and the Dorton Arena in representing North Carolina on this important list.
One of only two original covered bridges in North Carolina, the other being Mt. Pisgah in Randolph County, the Bunker Hill Covered Bridge was built in 1895 by Andy L. Ramsour. Catawba County Commissioners in 1894 had asked nearby owners of Bunker Hill Farm to build and maintain a bridge that crossed Lyle’s Creek on the old Island Ford Road, a former Native American trail. The landowners hired Ramsour, keeper of the Horseford Covered Bridge that spanned the Catawba River north of Hickory. To protect its timbers from the weather, workers covered the bridge in 1900 with a ninety-one foot roof, and in 1921, replaced the wooden shingles with a tin roof. In 1985, the Bolick Family donated the bridge to the Catawba County Historical Association. Under the guidance of Arnold M. Graton, a master bridgewright from Ashland, New Hampshire, CCHA restored the structure in 1994.
David Fischetti, from Cary, North Carolina, the consulting engineer for the 1994 restoration and an instrumental part of getting the bridge designated as a national landmark, notes that General Herman Haupt was Chief of Military Railroads for the Union Army during the Civil War. A Philadelphia born civil and military engineer, author, professor, inventor, and industrialist, Haupt constructed an improved lattice truss bridge in “response to Ithiel Town’s 1820 and 1835 patents for the plank lattice timber truss.” “Haupt used the analytical methods he developed in the 1840s,” Fischetti writes, “to design a more efficient lattice truss which consisted of web members positioned only at locations which required support. Redundant members were removed, resulting in the improved lattice truss as described in his book General Theory of Bridge Construction published in 1851.”
In a letter to the U. S. Patent Office (“Specification of Letters Patent No. 1,445, dated December 27, 1839”) Haupt explained his new construction method: “The construction of a lattice bridge without counterbraces, but consisting simply of braces inclined at any proposed angle and ties which are perpendicular to the lower chord, the chords being either straight or curved.” Haupt went on to delineate the faults of the existing lattice truss. He found useless the “braces and counterbraces arranged at equal angles in opposite directions and pinned with wooden pins to horizontal chords at top and bottom.” He further concluded, “Theory, observation, and experiment [prove] that one half of the inclined pieces are of no use as counterbraces and badly answer the purpose of ties, that from their inclined position are exposed to a very considerable cross strain, which tends to split the timbers along the line of pins, and that the pins of the lower intersections are caused to bear a disproportionate share of the weight.”
The location of the Bunker Hill Covered Bridge played an important role not only in the Civil War but also during the American Revolution. In 1959, Dr. J. E. Hodges, President of the Catawba County Historical Association, relayed that following the Battle of Cowpens in 1781, General Morgan detached 531 British prisoners under the guard of Colonel William Washington’s dragoons and Colonel Charles McDowell over the Island Ford Road—the route where the bridge rests. The men crossed Lyle’s Creek at the Bunker Hill Ford on their way to the Island Ford of the Catawba River, where they were then conveyed to Virginia.
The bridge is located two miles east of Claremont on Hwy. 70.
By Nathan Moehlmann, Catawba County Historical Association
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Designed by the innovative Herman Haupt, the Bunker Hill Covered Bridge is one of only two surviving original covered bridges in North Carolina. Image courtesy of the Catawba County Historical Association.
An example of the lattice truss used to support covered bridges prior to Haupt's 1840s innovations. Image courtesy of the Catawba County Historical Association.
Herman Haupt designed a more efficient lattice truss which consisted of web members positioned only at locations which required support. Image courtesy of the Catawba County Historical Association.