Great Hollow Road Stone Arch Bridge (A.K.A. Etna Stone Bridge)
Backstory and Context
During the early portion of the twentieth century, Hanover officials sought to replace the older, decaying wooden bridges with something that could handle the weight of automobiles. In 1914, The Great Hollow Road Stone Arch Bridge opened in a rural part of Hanover referred to as the Etna area. The bridge allows travelers to traverse Great Hollow Road over Mink Brook, Hanover's largest tributary of the Connecticut River.
The dawn of the automobile era profoundly changed many aspects of American culture and forced all parts of its governments -- from federal to local -- to fund and construct roads and bridges. Hanover's government records during the first two decades of the twentieth century contain evidence of town officials seeking solutions to the problems created by automobile travel on old, unsuitable roads and bridges.
The bridge carries Great Hollow Road, which served as the primary access to Dartmouth College in the years before the Interstate Highways systems came into vogue.
In addition to their lack of strength and durability, wooden bridges suffered mightly from changing weather conditions, notably during the winter, and water damage. The town deemed building bridges with steel girders too expensive -- a state of the art type of engineering at that time and quickly growing into the most popular choice in most urban locations. Moreover, Dartmouth College offered Hanover free use of massive cut-stone pieces taken from a demolished bank building located on the college's campus. Thus, planners chose to construct an arched, stone bridge, and they relied on local builders rather than contractors as a means of saving money.
The Stone Arch Bridge has a radius of 17 ½ feet while the vault, constructed of local granite rubble, spans 24 ½ feet in width. The arch voussoirs are rock-faced ashlar measuring approximately 12 inches by 18 inches high with varying thickness or depths of the individual stone pieces. (The 6-inch thick concrete caps are not believed to be an original feature of the bridge.)
The emergence of New Hampshire Route 120 (Mount Support Road) diverted most of the traffic to Dartmouth away from Great Hollow Road, which has allowed the bridge to enjoy longevity. Thus, the bridge stands now as a monument to a time when the automobile took the country by storm. As well, the bridge stands as one of the few "new" stone bridges built in the twentieth century as most urban communities chose to use steel by the 1920s.
Barrett, Frank J. "Nomination Form: Great Hollow. Road Stone Arch Bridge." National Register of Historic Places. nps.gov. May 12, 1997. https://npgallery.nps.gov/pdfhost/docs/NRHP/Text/97000372.pdf
Billington, David P. Power, Speed, and Form: Engineers and the Making of the Twentieth Century. Princeton University Press, 2006.
Childs, Francis Lane, ed. Hanover, New Hampshire, a Bicentennial Book: Essays in Celebration of the Town's 200th Anniversary. Hanover: Hanover Bicentennial Committee, 1961.
Petroski, Henry. "Engineering: Reusing Infrastructure." American Scientist 98, no. 3 (2010): 191-95. http://www.jstor.org/stable/27859502.
Photo taken by Royce and Bobette Haley in May 2015 ( http://bridgehunter.com/nh/grafton/11400980005300/ )