Year constructed: 1882
Bridge type: Pin-Connected Pratt Through Truss
National Register of Historic Places status:
Listed
Length: 400 feet
Width: 15.9 feet
Spans: 2
FHWA: 131670
Jurisdiction: Dallas County
Location: River Street ("Old Waukee Road") over North Raccoon River in Adel, Section 29, T79N-R27W (Adel Township)
Details
Located as it is on the North Raccoon River, Adel, the Dallas County seat, was the site of one of the county's earliest river crossings. A ferry was first established at the eastern outskirts of town in March 1850--three years after the town's platting--to provide safe passage across the river during periods of high water. The county later contracted with local bridge builder Johnathan Peppard to construct a timber structure at this point that would carry the Waukee Road. However, this early span had deteriorated to the point of replacement by the early 1880s. In June 1882 the Dallas County Board of Supervisors received a citizens' petition for a replacement bridge. The board studied the request, solicited competitive proposals from several bridge companies, and in September awarded a contract to fabricate and erect a two-span wrought iron truss to the King Iron Bridge and Manufacturing Company for $12,500. The Cleveland, Ohio firm used wrought iron components rolled by the Carnegie mills in Pittsburgh to fabricate these medium-span Pratt through trusses, using a King standard Pratt configuration. The company erected the trusses on steel cylinder piers later that year. The Adel bridge has carried vehicular traffic since, although due to the construction of a new highway bridge in 1932, it has been relegated to secondary road status. The trusses and two of the three cylinder piers remain intact, but the approach spans on the bridge's east end and one of the piers have subsequently been replaced.
From the early 1880s until the establishment of state bridge standards in 1913, the pin-connected Pratt through truss was virtually the exclusive structural type for medium-span roadway crossings in Iowa. Its standardized fabrication, economy of materials and ease of erection made it a mainstay among the various state and regional bridge companies. Thousands of such trusses were built throughout the state during this period, and numerous examples remain in place today. The Adel Bridge is noteworthy as among the oldest remaining Pratt trusses in Iowa. It is also important for its two-span configuration. Although many multiple-span trusses were erected in Iowa in the late 19th century, almost all have subsequently been demolished. The Adel Bridge is thus a well-preserved, early remnant of early wagon truss construction - a regionally important crossing of a major river [adapted from Fraser 1991].