C&NW Wilson Creek Bridge

Located in Menomonie, this lattice through truss bridge carries the former Chicago, St. Paul, Minneapolis & Omaha Railway Menomonie branch over Wilson Creek along Meadow Hill Drive. The first bridge at this location was a timber pile trestle, which was periodically upgraded through the late 19th and early 20th Centuries. By the mid-20th Century, it was desired to replace the wooden bridge with a more permanent structure. In 1943, a truss span was relocated here, and installed on timber pile substructures. The bridge was again altered in 1957, when a deck girder span was installed on the north end, and concrete substructures constructed, giving the bridge its present configuration. Currently, the bridge consists of a 150-foot, riveted quadrangular lattice through truss span, approached by a 47-foot deck plate girder span. The abutments and pier base are constructed of concrete, and the pier is constructed of a steel bent. The steel bent appears to also be secondhand material, reused from an unknown location. The bottom of this bent has been encased in concrete to protect the steel from pooling water. An unknown contractor constructed the substructures.

The truss span was reportedly fabricated in 1896, and originally used at an unknown location. The Dunn County news reported on August 4th, 1943 that a new steel railroad bridge was being constructed to replace a damaged structure; and that the steel was salvaged from the Spring Valley to Elmwood line, abandoned that same year. It is unknown where the materials may have came from, as most bridges on that line were wooden trestles and Howe trusses in 1917. Because of this, it is believed that the truss span may have been reused on that branch in the 1920s. Based on the design, is believed that Lassig Bridge & Iron Works fabricated the span. Lassig Bridge & Iron Works fabricated dozens of these lattice trusses for the Omaha Road and the Chicago & North Western during the late 19th Century. The truss span uses a standard design for the era, including a pedimented portal bracing with decorative heel bracing, a combination of built-up and solid members and a traditionally composed floor. Typical of this type of span, the bottom chord is constructed of two parallel beams, while the endposts and upper chord are composed of built-up beams with X-lacing on the back/bottom. Rolled members are used for the compression members near the ends of the truss, while inner compression members are constructed of V-laced members. The deck plate girder span was originally fabricated in 1905 by the American Bridge Company, and was originally installed at an unknown location. The span uses a standard design, with shallow girders and an open floor.

This type of truss design is relatively uncommon throughout the United States. However, a few railroads preferred the design, such as the Chicago, Rock Island & Pacific Railway (Rock Island), the Chicago & North Western Railway (C&NW) and the Omaha Road. Spans constructed in the early 1880s for the Omaha Road featured an arched and pedimented lattice portal bracing, light sway bracing and laced members. The second generation was nearly exclusively constructed by Lassig Bridge & Iron Works between 1884 and 1900, and featured heavier members and a pedimented portal bracing. While the design fell out of favor for the Rock Island and Omaha Road around the turn of the 20th Century, the design remained popular with the C&NW into the 1920s. The discontinuance of the lattice design is one of the few examples of the Omaha Road and C&NW bridge engineers having differing thoughts on bridge designs. This particular span uses a design typical for the second generation of quadrangular lattice through trusses. Railroads often reused steel and iron spans, as it provided a cost effective way to rebuild bridges on branch lines without requiring large amounts of new material. Overall, the bridge appears to be in good condition, with no significant deterioration noted. The bridge has been acquired by the City of Menomonie for potential future trail use. The author hopes that this bridge will be reused and preserved for generations to come. The author has ranked this bridge as being moderately significant, due to the truss design, age and unclear history.