DAIR Sixmile Creek Bridge

Located alongside Iowa Highway 12 south of Hawarden, this deck plate girder bridge carries a former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) line over Sixmile Creek. The first bridge at this location was a timber pile trestle bridge, which had been periodically renewed since it was first constructed. In the 1930s and 1940s, the Milwaukee Road made improvements to this line, replacing deteriorated timber bridges with steel spans. A secondhand steel span was installed at this location in 1936. In 1955, the timber approaches were extensively rebuilt and the bridge was raised due to repeated floods. Currently, the bridge consists of a single 63-foot deck plate girder span, approached by three 16-foot timber pile trestle spans on either end. The entire bridge is set onto timber pile substructures. The steel span was originally fabricated in 1894 for use at Bridge #I-792, a large viaduct over Chicken Bristle Creek located near Elmira, Missouri. When a new alignment was constructed between Polo, Missouri and Kansas City in the early 1930s, spans from the original alignment were salvaged for reuse. Two spans from the viaduct were combined into a single double strength span and installed here. The steel span uses a somewhat unusual design for a deck girder, with four girder lines and tapered ends at the bottom of the girder. American Bridge Works fabricated the superstructure, while the timber components were constructed by railroad company forces. Deck plate girder spans were commonly used by railroads, as they were durable and easy to construct. Railroads often reused steel spans, as it provided a cost effective way to upgrade bridges without requiring a large amount of new material. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being locally significant, due to the common design.