UP Appleton Avenue Bridge (Milwaukee)

Located on the northwest side of Milwaukee, this through plate girder bridge carries the former Chicago & North Western Railway mainline over Appleton Avenue (former US Highway 41, now Wisconsin Highway 175). The first bridge at this location was constructed in 1911 as the Milwaukee, Sparta & North Western Railway constructed a line between Wiscona and Wyeville. This first bridge consisted of a double track 35-foot deck plate girder span, set onto concrete abutments. American Bridge Company fabricated the superstructure, while the Cleary-White Construction Company constructed the abutments. In the late 1920s and early 1930s, the Wisconsin State Highway Commission worked to improve intersections of railroads and major roadways. One of the priority projects was to widen the bridge over US Highway 41, which served as a major north-south arterial in Milwaukee. In 1933, an agreement was reached with the C&NW to reconstruct the underpass, and contracts were awarded in late 1933. In 1934, a larger through plate girder bridge was constructed to replace the original deck plate girder bridge, which may have been reused at other location(s). In the 1950s and 1960s, the Milwaukee Area saw unprecedented growth of the highway network, with several new expressways proposed, and other major arterial roadways widened to accommodate growing traffic. In 1967, the bridge was lengthened by replacing the west abutment with a pier and adding a second similar through plate girder span, giving the bridge its present configuration. This method of lengthing underpasses was used at a number of locations in the Milwaukee Area, where the original pre-World War II underpass was too narrow to serve increasing automobile traffic.

Currently, the bridge consists of a 68-foot and a 62-foot through plate girder span, set onto concrete substructures and constructed at a moderate skew. The east (68-foot) span uses a typical design for the 1930s, with heavily constructed girders, a ballast deck floor system and rounded and tapered girder ends. The west (62-foot) span uses a similar design, with less rivets than the eastern span. Both spans use a floor system constructed of parallel I-beams, which are placed between the girders. A sheet metal deck is installed on the spans, which provides the ballast deck. While constructed some 33-years apart, the abutments use a similar design, with sloped wing walls extending parallel to the roadway beneath. The pier uses a rounded concrete design, typical of 1950s and 1960s grade separations in southeast Wisconsin. Strobel Steel Construction Company reportedly fabricated and erected the east span, in addition to constructing the original abutments. An unknown contractor fabricated the west span, and an additional unknown contractor modified the bridge by constructing a new pier and west abutment. Through plate girder spans were commonly used by railroads, as they were durable, easy to construct and maximized clearance underneath. US Highway 41 was moved from Appleton Avenue in the early 1950s, with the former route becoming Wisconsin Highway 175. Overall, 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 and newer age.