© Iowa Department of Transportation
BH Photo #256945
Built in 1921, the Herrold Bridge spans Beaver Creek near the abandoned town of Herrold on the Iowa Army National Guard installation in west-central Polk County. This outstanding early structure is comprised of three arched concrete deck girder spans, cantilevered from concrete abutments and piers. County engineer M.D. Blue surveyed the site late in 1920 for a new bridge that would replace an earlier timber pile structure here. That year engineers for the Iowa State Highway Commission's Bridge Department designed the new concrete structure, as well as a 150-foot steel through truss--the two configurations to be bid as alternates. As drawn up by ISHC, the deck girder alternate was comprised of a 64-foot central span, flanked on both sides by 42-foot girders; the bridge would consume some 607 cubic yards of concrete and 52,000 pounds of reinforcing steel. Polk County solicited competitive bids for the two bridges early the following year, using ISHC's designs and specifications. On March 29, 1921, the county awarded a contract to Ben Cole of Ames, Iowa, to build the concrete girder bridge for $24,550. Cole began work on the substructural excavation soon thereafter, completing the new Herrold Bridge later that year. It has functioned in place since, in essentially unaltered condition.
The choice to use a rather esoteric structural type at this crossing was for the 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 ISHC 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 spans at Goldfield in Wright County, and this one at Herrold in Polk County. In its 1917 annual report, ISHC deemed the cantilevered deck girder design "particularly well adapted for use on deep drainage ditches and streams subject to widening." 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. The Beaver Creek structure allowed the ISHC the opportunity to demonstrate the superiority and flexibility of concrete for bridge construction. With a 68-foot center span and a total length of 156 feet, the Herrold Bridge is an excellent example of this type of construction. It is one of the most technologically significant of the state's numerous concrete girder bridges [adapted from Crow-Dolby and Fraser 1993].
- Concrete deck girder bridge over Beaver Creek
- Herrold, Polk County, Iowa
- Closed to all traffic
- Built 1921
- - Ben Cole & Sons Construction Co. of Ames, Iowa
- Iowa State Highway Commission of Ames, Iowa (Designer)
- Cantilevered concrete deck girder
Length of largest span: 68.0 ft.
Total length: 156.0 ft.
Posted to the National Register of Historic Places on May 15, 1998
- Approximate latitude, longitude
- +41.72200, -93.75030 (decimal degrees)
41°43'19" N, 93°45'01" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 15/437592/4619182 (zone/easting/northing)
- Quadrangle map:
- Inventory numbers
- NRHP 98000490 (National Register of Historic Places reference number)
BH 49371 (Bridgehunter.com ID)
- March 26, 2015: Photo imported by Dave King
- June 21, 2013: New photo from Luke Harden
- August 16, 2011: Added by Luke Harden