Eagle Flats Railroad Bridge (North)

Located beneath the Oneida Street Bridge, this long girder and steel stringer bridge carries the former Chicago & North Western Railway mainline over the Fox River alongside the former Milwaukee Road bridge. The first bridge at this location consisted of a long timber pile trestle, set onto piers constructed of timber cribs. In 1889, two stone piers (piers #30 and #31), a new stone west abutment and two through plate girder spans (spans #31 and #32) were added to the west end of the bridge. By the turn of the 20th Century, the bridge had become in poor condition, and the railroad began investigating options to construct a permanent structure at this location. The first proposal involved constructing numerous 48-foot through plate girder spans, set onto stone substructures. This plan proved to be unfeasible, and the plan was instead modified to constructing several smaller spans. Work on the bridge began in 1901 as part of a joint project with the Milwaukee Road to improve this crossing. Initially, the bridge consisted of two 55-foot through plate girder spans on the west end, with several steel stringer spans approaching from the east. In 1922, the bridge was modified, and the western spans were replaced with deck plate girder spans, giving the bridge its present configuration. Currently, the bridge consists of an 18-foot steel stringer (span #1), 26 24-foot steel stringer spans (spans #2 through #27), two 22-foot steel stringer spans (spans #28 and #29), a 16-foot deck plate girder span (span #30) and two 55-foot deck plate girder spans (spans #31 and #32). Piers #1 through #29 are constructed of steel cylinders, while piers #30 and #31 are constructed of concrete. The east abutment is also constructed of concrete, while the west abutment is constructed of both stone masonry and concrete. The west end of the bridge is slightly curved, and the entire bridge is set at a modest skew.

The western spans (spans #31 and #32) are unusual , consisting of multiple deep plate girders which do not contain exterior stiffeners. This style of span was often used for shorter shallow spans, but is unusual for use on deeper spans constructed at this length. Span #30 consists of a shallow deck plate girder span, which may have been reused here from elsewhere and appears to have several modifications. This span initially crossed a spur of the C&NW Northern Wisconsin Division, which served industry south of this bridge. Spans #1 through #29 all consist of standard steel stringer spans, consisting of six shallow beams arranged into two sets of three. A spur also crossed under span #2, and was carried by a timber pile trestle. Chicago Bridge & Iron Company fabricated spans #1 through #29, while unknown contractors fabricated spans #30, #31 and #32. The Adolph Green Construction Company constructed all substructures for the bridge, and an unknown contractor made alterations to piers #30 and #31 when the present western spans were installed. 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 #30 was removed in 1928 and the spur under span #2 was removed in the 1940s. Since the 1922 construction, the bridge has seen no significant alterations, and remains in regular use. Overall, the bridge appears to be in fair condition, with no significant deterioration noted. The author has ranked this bridge as being locally significant, due to the common design.