Historic Bridges of Iowa
||pinned Pratt pony truss|
||remains in use|
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220th Street over Kemp Creek, 4.2 miles west of Corning, Section 1, T71N-R35W (Nodaway Township).
Adams County's Snider Bridge is a medium-span pony truss built in 1885 to cross an unnamed stream four miles west of Corning. In June of that year the Adams County Board of Supervisors received petitions from county residents for the placement of seventeen small bridges. The largest of these proposed bridges was that requested by George Snider, who asked that a 60-foot bridge be built in the west part of Section 31 of Quincy Township. For the two longest spans, including the Snider Bridge, the board decided to solicit bids to erect iron structures.
On June 15th bids were received from eight firms, and a contract to build both bridges was awarded to Reeve, Ward and Keepers of Clinton, Iowa. The contract price for both crossings was $1,451.00. Completed later that year, the Snider Bridge has carried wagon and automobile traffic ever since. Although the substructure and approach spans have been replaced over time, the pinned Pratt truss remains today in unaltered condition.
The Pratt through-truss design was patented in 1844 by Thomas and Caleb Pratt, the Pratt design is distinguished by vertical members acting in compression and diagonals that act in tension.
"The Pratt truss is the type most commonly used in America for spans under two hundred and fifty feet in length," noted bridge engineer J.A.L. Waddell wrote in 1916. "
Its advantages are simplicity, economy of metal, and suitability for connecting to floor and lateral systems." Virtually all of the major regional bridge fabricators manufactured Pratt trusses and marketed them extensively to Iowa's counties. This included the fledgling Clinton, Iowa, firm of Reeve, Ward and Keepers, founders of what would grow to become the state's most prolific bridge builder--the Clinton Bridge and Iron Works. Thousands of pinned Pratt trusses were erected throughout Iowa, in both through- and pony-truss configurations, and many remain in service today.
The Snider Bridge is distinguished as one of the earliest of the Pratt pony trusses still standing in the state. The oldest remaining roadway bridge in Adams County, Snider Bridge is further distinguished as the earliest truss in the state attributable to Clinton Bridge and Iron Works. In well-preserved condition, the Snider Bridge is an important early resource of Iowa transportation [adapted from Fraser 1991].http://www.douglascoulter.com/BridgeSigns/clinton_bridge.html Clinton Bridge & Iron Works