Year constructed: 1929
Bridge type: Concrete Open Spandrel Arch
National Register of Historic Places status:
Listed
Length: 106 feet
Width: 24 feet
Spans: 1
FHWA: 010270
Jurisdiction: City of Shell Rock
Address: Cherry Street over tributary of the Shell Rock River in Shell Rock, Section 11, T91N-R15W (Shell Rock Township)
Details
On March 7, 1929, the Butler County Board of Supervisors awarded a contract to the A. Olson Construction Company to build a concrete arch bridge on Cherry Street in the town of Shell Rock. The Waterloo-based bridge builder erected the structure, which replaced a 140-foot steel through truss, using special plans designed in January 1929 by the Iowa State Highway Commission. The highway commission's plans - Butler County Design No. 229 - called for a 100-foot reinforced open-spandrel concrete arch, with a 24-foot roadway width and a 5-foot sidewalk. The span required 544.6 cubic yards of concrete and 16,960 pounds of reinforced steel in its arch ribs. Olson completed the structure during the summer of 1929 for a cost of $15,690. County supervisor's records show that between May and August 1929, Olson received four Butler County warrants, totaling $23,780.58. These payments evidently included compensation for the Cherry Street Bridge. During its existence, the span has carried local traffic over a tributary of the Shell Rock River. At some point the original lights were removed from the guardrail bulkheads, but otherwise, the bridge retains a high degree of physical integrity.
The significance of this handsomely proportioned bridge is technological and aesthetic. Despite an often-stated preference for concrete for highway bridges, the state highway commission designed steel trusses for its medium- and long-span structures. As a result, most of Iowa's concrete arches feature relatively short spans and filled spandrel configurations. The 1992 statewide historic bridge inventory identified fewer than ten open-spandrel arches, all in urban or small-town settings. At these locations ISHC employed open spandrel arches, regarded by many engineers of the time to embody the highest aesthetic of bridge design, to blend its bridges with the built environment. A well-preserved, well-proportioned example of an uncommon structural type, the Cherry Street Bridge thus represents a rare foray into aesthetics by a highway department widely known for its starkly utilitarian engineering
[adapted from Fraser 1990].