CPKC Greenfield Avenue Bridge (Milwaukee)

Located on the south side of Milwaukee, this concrete slab bridge carries the former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) mainline over Greenfield Avenue. 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. One of the first structures constructed was located over Greenfield Avenue. This bridge was constructed during the 1915 construction season.

Currently, the bridge consists of two 22-foot concrete slab spans over the roadway and two 11-foot concrete slab spans over the adjacent sidewalks. The bridge is set onto an early art-deco style of concrete pier and concrete abutments. The two main spans consist of relatively thin concrete slabs, which appear to have originally been cast off-site and later installed. The sidewalk spans are considerably deeper, and may have been constructed integrally with the abutments and adjacent piers. The piers are composed of several concrete columns, connected by a concrete beam at the top. Similar to other nearby bridges, the abutments consist of rectangular structures with sloped wing walls. Milwaukee Road Bridge & Building Department labor constructed the bridge, typical of concrete construction along the Milwaukee Road in the early 20th Century. Concrete slab spans became popular for grade separations after 1910, as they were durable, easy to construct and minimized hazards to the public below. While the bridge was initially constructed for seven tracks, only three remain in use; while the west end of the bridge is currently used by the Kinnickinnic River Trail. Overall, the the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked the bridge as being locally significant, due to the common design.