CPKC 1st Street Bridge (Milwaukee, North)

Located on the south side of downtown Milwaukee, this large trough floor steel stringer bridge carries the former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) mainline over 1st Street and Oregon Street. In the early 20th Century, the City of Milwaukee ordered grade separations at many of the busy railroad lines throughout the City. Inspired by track elevation projects in Chicago, early ordinances were passed for both track elevation and depression in approximately 1904, and the ordinances later expanded to include several other lines throughout the City. In approximately 1914, an ordinance was passed requiring the elevation of the Milwaukee Road mainline from a point near Greenfield Avenue to downtown Milwaukee. Similar to many other grade separation ordinances throughout the United States, the City of Milwaukee dictated the dimensions required for each subway. Work on the elevation project began in 1915, and the project was completed sometime in 1916. The subway at 1st Street (then Clinton Street) and Oregon Street represented a significant challenge, due to the unique geometry required. During the 1916 construction season, this subway was completed.

Currently, the bridge consists of nine trough floor steel stringer spans, approached by five concrete slab spans on the south end. Due to the unusual geometry required, the bridge uses a large curve, extensive skewed spans and spans which are present on one side of the structure and not the other. The south approach is composed of five 25-foot concrete slab spans, which are visible as only three spans on the southwest face of the bridge. Continuing north, the east sidewalk along 1st Street is crossed by a 20-foot trough floor steel stringer span, followed by a 38-foot and a 40-foot span of the same design across the roadway. The west sidewalk is crossed by a 26-foot span (span #9), followed by another 26-foot span against an adjacent building (span #10) and a 16-foot span over the south sidewalk of Oregon Street (span #11). Due to the unusual curvature of the bridge, these spans appear as one span on the northeast face of the structure. Oregon Street is crossed by two 25-foot trough floor steel stringer spans, followed by a 16-foot span over the north sidewalk. The bridge is set onto a combination of concrete and steel bent substructures. The superstructure was fabricated by an unknown contractor, while labor employed by the Milwaukee Road Bridge & Building Department constructed the concrete portions of the bridge. Trough floor spans became popular for grade separations in the early 1910s, as they could easily be adapted for complex geometry and provided a strong span with minimal maintenance required. Currently, both tracks of the bridge remain in use. Overall, the bridge appears to be in fair to poor condition, with some deterioration noted to the structure. A number of minor repairs were made to the structure in the late 2010s. The author has ranked the bridge as being locally significant, due to the common design.