CPKC Markham Creek Bridge

Located on the south side of Janesville, this deck plate girder bridge carries a former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) line over Markham Creek. The first bridge at this location likely consisted of a timber pile trestle bridge, constructed when the line was first built. Between the 1920s and 1940s, the Milwaukee Road invested significant capital into their lines, replacing timber bridges with steel structures. In 1931, a new bridge was constructed at this location, using rebuilt secondhand deck plate girder spans. Currently, the bridge consists of three 30-foot deck plate girder spans, approached by a 15-foot timber pile trestle span on either end. The entire bridge is set onto timber pile substructures. It is believed that the superstructure was originally fabricated in approximately 1900 for use at up to six unknown locations. The south and north spans are nearly identical, using shallow plate girders which lack a vertical stiffener at the center. The center span uses a slightly deeper design, with stiffeners placed throughout the span. All four spans use four girder lines, which are arranged equidistant and appear to have been rebuilt by rebuilding the interior bracing with new lateral bracing, consisting of plate girder laterals. Unknown contractor(s) fabricated the main spans, and the Milwaukee Road Bridge & Building Department constructed the approaches and substructure. The Milwaukee Road often rebuilt short plate girder spans into "twinned" spans, with the alterations made at the bridge shop in Tomah, Wisconsin. Railroads often reused steel and iron spans, as it provided a cost effective way to upgrade bridges on branch lines without requiring large amounts of new material. During the 1930s, the Milwaukee Road upgraded bridges on numerous main and secondary lines, freeing up secondhand spans for reuse. The Milwaukee Road preferred to reuse spans wherever possible, and continued the practice into the late 20th Century. Since the initial construction, the bridge has seen few alterations, and remains in regular use. 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 and unknown history.