Chippewa Falls Railroad Bridge

Located in Chippewa Falls, this iconic through truss bridge carries the former Chicago, St. Paul, Minneapolis & Omaha Railway line over the Chippewa River. The first bridge at this location consisted of a six span wooden Howe through truss bridge, set onto timber piers. In the late 1880s and early 1890s, the Omaha Road made significant improvements throughout the system, replacing wooden bridges with steel and stone. Between 1891 and 1892, the bridge would be replaced by a new iron truss bridge, consisting of six spans set onto timber piers and approached by wooden pile trestle spans on either end. The bridge remained unchanged through much of the 20th Century, requiring only occasional repairs to the timber components of the bridge. On July 20th, 1993, the bridge was intentionally set on fire, and the northern two spans collapsed into the river. To repair the bridge, three deck plate girder spans were reused from an abandoned bridge nearby, and new steel pile piers built to replace the collapsed spans. The bridge was significantly upgraded in 2014, when the truss spans were shifted to new concrete and steel piers, and the original south approach replaced with a modular concrete girder span, giving the bridge its present configuration.

Currently, the bridge consists of two 100-foot and two 160-foot riveted quadrangular lattice through truss spans. These spans are approached on the north by a 42-foot steel stringer, three 100-foot deck plate girder spans and a 24-foot steel stringer span. The south approach is comprised of a single 24-foot modular concrete girder span. The entire bridge is set onto piers consisting of steel piles and caissons, capped with concrete. The truss spans were fabricated in 1891 by the Lassig Bridge & Iron Works, and consist of a standard design for the Omaha Road. These trusses use a pedimented lattice portal bracing with decorative heel bracing, a combination of built-up and solid members and a traditionally composed floor. The deck girder spans were fabricated in 1916 by the Wisconsin Bridge & Iron Works, and were originally part of an eight span bridge across Lake Wissota northeast of Chippewa Falls. When that bridge was abandoned, the girders were salvaged, and three reused here. It is unknown where the remaining five spans were reused, but it seems likely that the spans were repurposed instead of scrapped. The girders are heavily constructed, and were exceptionally long for the time period when they were fabricated. The two stringer spans appear to be modern, and were likely constructed for this bridge. When the bridge was rebuilt in 2014, the truss spans were shifted 30 feet south, and an original 12-foot stringer span in the middle of the bridge replaced with the current 42-foot span.

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 bridge uses a design typical for the second generation of quadrangular lattice through trusses. Overall, the bridge appears to be in good condition, with no significant deterioration noted. It appears that the trusses were also strengthened at an unknown date. The bridge remains in use, carrying heavy frack sand cars. Because of the 2014 rehabilitation, it is likely that this bridge will continue to serve railroad traffic in its current configuration for years to come. The author has ranked this bridge as being regionally significant, due to the truss design, age and unique history.