UP National Avenue Bridge (Milwaukee)

South Side, Milwaukee, Milwaukee County, Wisconsin

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Name	UP National Avenue Bridge (Milwaukee) Chicago & North Western Railway Bridge #1553 1/2A
Built By	Chicago & North Western Railway
Currently Owned By	Union Pacific Railroad
Builder	Chicago & North Western Railway Labor
Length	82 Feet Total, 25 Foot Largest Spans
Width	4 Tracks, 2 In Use (Formerly 10 Tracks)
Height Above Ground	12 Feet 4 Inches
Superstructure Design	Concrete Slab
Substructure Design	Concrete
Date Built	1915
Traffic Count	1 Train/Day (Estimated)
Current Status	In Use
Chicago & North Western Railway Bridge Number	1553 1/2A
Union Pacific Railroad Bridge Number	83.16
Significance	Local Significance
Documentation Date	10/7/2023

In the early 1850s, several railroad companies began constructing railroad lines radiating from Chicago. In 1855, the Chicago & Milwaukee Railroad (C&M) constructed a 45-mile railroad line, extending north from an existing railroad line at Ashland Avenue and Armitage Avenue in Chicago to the Wisconsin State Line near Kenosha. At the same time, the Milwaukee & Chicago Railroad (M&C) constructed an additional 40 miles north to Milwaukee. The two railroads would be consolidated into a new railroad known as the Chicago & Milwaukee Railroad (C&M) soon after completion, and would come under control of the Chicago & North Western Railway (C&NW) in 1866. The C&M was leased to the Chicago, Milwaukee and North Western Railway (CM&NW) in 1883. The C&NW acquired control of the CM&NW soon after. The C&NW had constructed and acquired a large network of railroad lines through the Midwest. This line formed a portion of the principal north mainline of the C&NW, eventually extending to northern Wisconsin and the Upper Peninsula of Michigan. Due to increasing traffic along this line, a second track would be constructed between 1890 and 1892.

In the late 19th Century, railroad traffic had become a significant safety hazard for the City of Chicago. A solution was devised to elevate the railroad tracks throughout the city, placing the railroads upon embankments and constructing subways at each street. In 1898, the C&NW completed track elevation and a third track from Ashland Avenue to Balmoral Avenue; followed by Balmoral Avenue into Evanston between 1907 and 1910. The C&NW would become a prominent railroad in the Midwest, eventually building a system over 11,000 miles long. Throughout the 20th Century, this line would continue to be an integral part of the C&NW system. The second track would be removed north of Kenosha after 1959. In 1995, the C&NW would be purchased by the Union Pacific Railroad. Union Pacific continues to operate the route as the Kenosha Subdivision. Metra operates a commuter service, the Union Pacific-North Line over the Chicago to Kenosha section.

Located on the south side of Milwaukee, this concrete slab bridge carries the former Chicago & North Western Railway freight yard 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.

Originally, the bridge was constructed to carry 10 tracks. 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. The substructures use a standard design for the era, and the piers are constructed of concrete columns connected by concrete arches. 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. Between 1995 and 2000, the western six tracks and bridge were removed, leaving the current four track structure. Currently, only two of the tracks remain in use. 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.

Citations

Build date	Chicago & North Western Railway Valuation Notes at the Chicago & North Western Historical Society Archives
Railroad History Citation	ICC Valuation Information, Compiled by Richard S. Steele