C&NW National Avenue Bridge (Milwaukee)

Located on the south side of Milwaukee, this concrete slab bridge carries the former Chicago & North Western Railway passenger line over National 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 C&NW tracks at Washington Street and National Avenue. 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. During the 1915 construction season, three subways across National Avenue was completed by the C&NW. The two western subways served the passenger line and Allis Depot, while the eastern subway carried a freight yard.

Currently, the bridge consists of two 25-foot concrete slab spans over the roadway and two 16-foot concrete slab spans over the adjacent sidewalks, set onto concrete substructures. The superstructure consists of standard concrete slab spans, which have a beveled shape and decorative paneling. The superstructure is covered by a decorative concrete fascia on the east side, which resembles a concrete arch. The substructures use a standard design for the era, and the piers are constructed of concrete columns connected by concrete arches. Originally, a second bridge was located immediately east of this structure, with the depot located between the two structures at the south abutment. However, this parallel bridge was removed between 1995 and 2000. Labor employed by the C&NW constructed the bridge, and the structure was likely designed by railroad engineers. Concrete slab spans became popular for grade separations after 1910, as they were durable, easy to construct and minimized hazards to the public below. Originally, the bridge was constructed for two tracks, with one remaining intact until approximately 2020. Currently, the bridge carries a private pedestrian walkway, maintained by a factory north of the bridge. Overall, the the bridge appears to be in fair condition, with some spalling noted throughout the structure. The author has ranked the bridge as being locally significant, due to the common design.