Eagle Flats Railroad Bridge (South)

Located beneath the Oneida Street Bridge, this long girder and steel stringer bridge carries the former Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road) Appleton Branch over the Fox River alongside the former Chicago & North Western Railway bridge. The first bridge at this location likely consisted of a long timber pile trestle, constructed when the line was first built. The first permanent improvements to the structure were made in 1894, when two through plate girder spans were constructed at the west end of the bridge. The remainder of the timber pile trestle was replaced by steel stringer spans in 1901 as part of a joint project with the C&NW to improve this crossing. The most recent alterations to the bridge were made in 1972, when the eastern two spans (spans #1 and #2) were replaced by modern steel stringer spans, giving the bridge its present configuration. Currently, the bridge consists of two 55-foot type "B" through plate girder spans, a 15-foot deck plate girder span, 28 24-foot steel stringer spans and an 18-foot steel stringer span on the east end. The entire bridge is set onto steel cylinder piers and concrete abutments. At the west end of the bridge, the westernmost span is curved, and all spans throughout the bridge are slightly skewed.

The western spans follow a standard design for type "B" girders, one of several standard Milwaukee Road plate girder designs. Typical of spans of this design, the floor is placed approximately halfway up the girders, and is composed of plate girder floorbeams, placed throughout the span. Unique to this design, no stringers are used to carry the ties, and instead the ties are set directly onto plates riveted to the girders. Both spans use modest sized girders with squared ends. This design was used by the Milwaukee Road in the 1890s. It is believed the main benefit of this design is that it required less material, as it did not contain stringers. Span #3 consists of a shallow deck plate girder span, which originally crossed a spur of the C&NW. This span appears to be heavily constructed for its length, and was possibly modified and reused from another location. Spans #4 through #30 all use an identical design, which consists of six shallow beams arranged into two sets of three. Spans #31 and #32 use a similar design with bolted connections instead of riveted connections. A second C&NW spur crossed under span #31 on a timber pile trestle bridge. All piers follow a similar design, with steel cylinders which are filled with concrete. The abutments use a modified version of a standard design due to the proximity of the adjacent bridge and terrain on either bank. Lassig Bridge & Iron Works fabricated spans #1, #2 and piers #1 and #2; while unknown contractors fabricated the remainder of the superstructure. Labor employed by the Milwaukee Road Bridge & Building Department is believed to have constructed all remaining substructures.

Girder and stringer bridges were commonly used by railroads, as they were durable and easy to construct. Long bridges composed of several short spans were a popular design for crossings of canals and waterways in the Fox Cities, as it is believed that the unpredictable nature of the river required more piers with less bearing capacity. Many bridges in the Fox Cities area use a similar design to this bridge, due to the dynamic nature of the Fox River and need for lengthy, permanent structures with no concern for clearance underneath. Steel cylinder piers were popular for long bridges in this area, as they could easily be constructed under live traffic without requiring cofferdams or dredging. The railroad spur under span #3 was removed in 1928 and the spur under span #31 was removed in the 1940s, giving the waterway its present configuration. This bridge was abandoned by the early 1980s, and has remained unused since. Overall, the bridge appears to be in fair to poor condition, with some settlement noted at piers #2 and #3. The City of Appleton investigated reusing this bridge as a pedestrian crossing in the 2010s, but ultimately determined that reuse was not feasible, and a new pedestrian bridge would provide a more suitable crossing. The author has ranked this bridge as being locally significant, due to the common design and unclear history.