In 1900 Des Moines bridge builder N.M. Stark built a pinned through truss over the Iowa River immediately west of the small town of Goldfield. This structure carried traffic for twenty years, before the county began contemplating its replacement. In 1920, the Iowa Bridge Company was awarded a $40,584 contract to build the most expensive structure in the county up to that time. "The new structure is to be of the cantilever deck girder type," the Wright County Monitor reported in March. "A pathway for pedestrians is provided on the south side of the structure and eight electroliers will furnish light."
The choice is to use a rather esoteric structural type at this crossing was, for the state highway commission, a logical extension of its design policies. ISHC had first developed the design for simply supported concrete girder bridges--designated Standard Series H--among its first standardized bridge plans in 1914. Three years later the Highway Commission designed its first cantilevered deck girder for a three-span structure over the Boyer River at Woodbine. The Woodbine Bridge was followed by a handful of other cantilevered girders in the 1910s and 1920s, including the Herrold Bridge and this bridge at Goldfield. According to the ISHC, a cantilevered span could carry more weight over a greater distance than a shorter, simply supported girder. Moreover, the arched profile of ISHC's cantilevered girders was considered more architecturally accomplished than the straight spandrel of simply supported girders.
Construction on the Goldfield Bridge was completed on June 27, 1922. The lampposts have been removed, but little else has changed during the bridge's nearly 70 years of service. It continues to carry vehicular traffic in the town of Goldfield, and maintains a high degree of structural integrity.
The decision to build a cantilevered concrete bridge at Goldfield was evidently made both for engineering and aesthetic reasons. A concrete structure was clearly more durable than a steel truss. And a cantilevered design could withstand greater loads than a simply-supported girder while providing greater clearance underneath. But regard for aesthetics was also a factor in the choice of a cantilevered deck girder design. From a strictly utilitarian standpoint, a simply supported steel stringer span could have been employed at far less cost. The highway commission's engineers, though, apparently believed that the arched concrete structure would be more harmonious in this small-town setting. The Goldfield Bridge gracefully blended aesthetics with functionality, one of the earliest remaining examples in Iowa of this uncommon concrete girder bridge type [adapted from Fraser 1991].
- Lost concrete cantilevered deck girder bridge over Boone River on Oak Street in Goldfield
- Goldfield, Wright County, Iowa
- No longer exists
- Built 1922; replaced 2004
- - Iowa Bridge Co. (1902-193X) of Des Moines, Iowa
- Iowa State Highway Commission of Ames, Iowa (Design)
- Concrete deck girder
Length of largest span: 64.0 ft.
Total length: 158.0 ft.
Deck width: 29.0 ft.
Posted to the National Register of Historic Places on May 15, 2008
- Approximate latitude, longitude
- +42.73712, -93.92463 (decimal degrees)
42°44'14" N, 93°55'29" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 15/424314/4732037 (zone/easting/northing)
- Quadrangle map:
- Eagle Grove
- Inventory numbers
- NRHP 98000456 (National Register of Historic Places reference number)
IA 5590 (Iowa bridge number)
BH 14808 (Bridgehunter.com ID)
- October 29, 2015: New photo from Luke
- March 26, 2015: Photo imported by Dave King
- March 23, 2013: Photo imported by Luke Harden
- July 26, 2011: Updated by Luke Harden: Added description