CPKC Richland Creek Bridge #4

Located between Rubio and Richland, this deck plate girder bridge is the fourth crossing of Richland Creek along a former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) mainline. The first bridge at this location was a timber pile trestle bridge, constructed when the line was first built. In the late 1900s and early 1910s, the Milwaukee Road invested significant capital into this line, replacing timber bridges with new concrete and steel structures. In 1909, the bridge was reconstructed with two steel deck plate girder spans, approached by concrete deck girder spans on either end. The most recent alteration to the bridge came in 2021, when the approaches were replaced with modern spans and the main spans were rebuilt with a new ballast deck. Currently, the bridge consists of two 45-foot deck plate girder spans, approached by four 16-foot concrete modular girder spans on the east end and three 16-foot spans on the west end. The entire bridge is set onto concrete substructures. An unknown contractor fabricated the main spans, while the substructures and original concrete spans were constructed by labor employed by the Milwaukee Road Bridge & Building Department. It is possible that the center spans were fabricated by American Bridge Company, which reportedly received an order from the Milwaukee Road around November 1909, when these spans were ordered.

The main spans follow a standard design, with two light plate girders covered by a ballast deck. Originally, the ballast deck was constructed from concrete panels, before being replaced with timber in the mid-20th Century and again replaced with reinforced concrete in 2021. The approach spans follow a standard design, consisting of modern precast concrete girder spans. Originally, the approaches used a unique design, consisting of two heavy reinforced concrete girders, connected by concrete cross frames and a ballast deck. The piers all consist of rectangular structures, while the abutments use a standard U-shaped design. During the late 1900s and early 1910s, railroads throughout the United States were experimenting with various reinforced concrete designs, which were intended to supersede timber and steel girder designs. The Milwaukee Road developed a handful of designs in-house, where J.H. Prior and C.F. Loweth served as the main bridge engineers for the railroad. Among the designs developed was a concrete girder design, which functioned similar to a steel deck girder. A handful of these spans were constructed between 1908 and 1911, mainly for mainline use. By 1912, the Milwaukee Road had selected a reinforced concrete slab span as the standard concrete bridge design going forward, due to the simple design, economy and versatility. It is believed one of the main drawbacks of the concrete girder design was that it had to be constructed offsite and installed on the superstructure, instead of being a monolithic structure. During the early 20th Century, the Milwaukee Road used company labor almost exclusively to construct concrete bridges and culverts, as the company found this arrangement to be more cost effective than constructing masonry by contract. Except for the 2021 alterations, the bridge has seen no significant alterations, and remains in regular use today. Overall, the bridge appeared to be in fair condition at the time of documentation, with some cracking and spalling noted throughout the concrete. The author has ranked this bridge as being moderately significant, due to the original unusual approaches. Today, the bridge would be ranked as being locally significant, due to the common design and modern alterations.