IR Fox River Bridge (Sheridan)

Located in Sheridan, this deck truss bridge carries the former Chicago, Burlington & Quincy Railroad over the Fox River. The first bridge at this location was constructed in 1871, and likely consisted of a timber truss bridge. In 1888, the bridge would be reconstructed with secondhand iron truss spans, reused from an unknown location. These truss spans consisted of 154-foot, pin-connected Whipple through truss spans, set onto new stone substructures. These spans were reportedly constructed in 1878, and were fabricated by an unknown builder. There are a number of locations which these spans may have been reused from, and 154-foot spans were a standard CB&Q size. It is also possible that the spans were converted from through trusses to deck trusses upon relocation here. The bridge was again rebuilt in 1905, when the southern Whipple deck truss was removed, and a new Pratt deck truss span installed. The two Whipple spans were then combined into a single double strength span for the north span. The most recent upgrades came in approximately 1975, when the Whipple span was replaced by three steel stringer spans, giving the bridge its current configuration.

Currently, the bridge consists of a 154-foot, 8-panel, pin-connected Pratt deck truss span, approached by two 54-foot and one 46-foot steel stringer on the north side. The bridge is approached by timber pile trestle spans on either end, and is set onto stone piers. New steel and concrete bents were constructed for the stringer spans in approximately 1965. The truss span was fabricated in 1905 by an unknown contractor, and consists of heavy members and a combination of riveted and pinned connections. This type of truss was commonly used by the CB&Q, as the simple design was both economical and durable. The Pratt truss design was the standard railroad truss bridge design during the late 19th Century, before it was superseded by riveted Warren designs in the early 20th Century. The CB&Q continued to construct pin connected spans after most railroads had switched to using riveted spans. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being moderately significant, due to the truss design.