Patent on Truss says 1876
Pin-Connected Pratt Through Truss
National Register of Historic Places status:
Bertram Road SE over Indian Creek, 1.5 miles east of Cedar Rapids, Section 30, T83N-R6W (Bertram Township)
This short-span through truss extends northwest-southwest across a stream in southern Linn County on Bertram Road about a mile east of Cedar Rapids. A plate located on the bridge's south portal notes that the Wrought Iron Bridge Company (WIBCo) erected the structure, using a design that it had patented in 1876. This bridge was presumably constructed shortly after the patent had been issued. WIBCo's patented design was a variation of a standard Pratt truss configuration, employing double-intersecting counter members radiating outward from the center of the span. WIBCo used this unusual Whipple truss configuration on another Linn County bridge, the Upper Paris Bridge, which it constructed in 1879, and on other bridges in the state. The Wrought Iron Bridge Company was established in 1864 and was ultimately absorbed into the American Bridge Company in 1900. It was one of several Ohio companies that provided many of Iowa's that provided many of Iowa's early metal bridges. This early wrought-iron truss features four timber stringer spans at its north approach and is supported by a combination stone/timber substructure. With no alterations of note, the bridge continues to carry intermittent vehicular traffic.
In its extensive dealings with the Wrought Iron Bridge Company in the 1870s, Linn County was simply following a regional trend. In the 1870s, Wrought Iron was one of the largest fabricators in America; its president, David Hammond, distinguished himself as one of the country's most prolific bridge innovators. The period of extensive rural road and bridge construction in the state during the 1870s coincided with the firm's ascendance in the industry, combining to create a booming market for WIBCo's regional sales representatives. The Ohio giant was extremely active in the region at this time. By 1885 WIBCo had installed 21,600 feet of bridges in Iowa, almost equaling the total output of WIBCo across America in its first nine years of business. That year WIBCo's bridges could be found in 41 of the state's 99 counties. The Indian Creek Bridge typifies WIBCo's penchant for the esoteric. Although the company marketed bowstrings and single-intersection Pratt trusses extensively, it also experimented with other forms, such as this double-intersection Pratt. The Indian Creek Bridge is significant as a well-preserved example of an uncommon early wagon truss configuration, built by what was perhaps the most influential bridge building in Iowa in the 1870s [adapted from Roise, Hess, and Crow-Dolby 1992].