Year constructed: 1909-1910
Bridge type: Rigid-Connected Pratt Through Truss
National Register of Historic Places status: Listed
Length: 80 feet
Width: 15.7 feet
Spans: 1
FHWA: 144120
Jurisdiction: Des Moines County
Location: Hawkeye Road over Hawkeye Creek, 6.5 miles northeast of Mediapolis, Section 14, T72N-R2W
Details
This short-span through truss carries a gravel-surfaced road over Hawkeye Creek northeast of Mediapolis. The bridge consists of a single rigid-connected Pratt through truss, supported by concrete abutments. The Hawkeye Creek Bridge dates to 1909. On September 23rd of that year the Des Moines County Board of Supervisors contracted with the Clinton Bridge and Iron Works for this 80-foot span and two other, smaller steel structures. Presumably completed the following year, the Hawkeye Creek Bridge has carried vehicular traffic since, in essentially unaltered condition.
When this bridge was let for bids in 1909, the Iowa State Highway Commission had not yet begun standardizing bridge design in the state. This left counties such as Des Moines to depend, as they had for decades before, largely on the bridge companies themselves for both engineering and construction. Firms such as the Clinton Bridge and Iron Works relied almost exclusively on pin-connected trusses up until about 1910, when they began to use riveted trusses as well. With its riveted Pratt through truss, the Hawkeye Creek Bridge was built during this transitional period between independently designed, rigid-connected trusses and ISHC standard design spans. It resembled the 1914 state standards in design but differed slightly in detail, indicative of its independent source. It is thus technologically significant as one of the few of the pre-ISHC riveted through trusses, the oldest example of its type in Iowa [adapted from Crow-Dolby and Fraser 1992].