Rock Island Trail - Spoon River Bridge

Located west of Wyoming, this through truss bridge carries the former Rock Island over the Spoon River. The first bridge at this location was likely a wooden truss bridge, set onto stone substructures. In 1899, the bridge would be rebuilt with the current structure, and the structure raised 6 feet to accommodate a reduction in grade on either side of the structure. Currently, the bridge consists of a 140-foot, 6-panel, riveted Warren through truss span, approached by three 75-foot deck plate girder spans and timber pile trestle spans on the east side. The truss span is set onto stone piers, while the deck plate girder spans are set onto steel cylinders and a concrete east pier. It appears there was originally a west approach, which was filled and replaced with a large concrete wall during the reconstruction. Lassig Bridge & Iron Works fabricated the superstructure, while the stone and cylinder substructures were constructed by an unknown contractor. The concrete pier and additions to the west pier and abutment were likely constructed by railroad company forces. The truss span is heavily constructed, using built-up and rolled members, riveted connections, a traditionally composed floor and an M-frame portal bracing. The deck plate girder spans appear to be standard, with heavy bracing and deep girders. While pin connected spans were still standard during this era, many railroads began to use riveted truss spans for bridges around the turn of the 20th Century. This design was stronger, while providing a comparable simplicity and economy to previous designs. The main disadvantage of the design was required use of field riveting, which was difficult prior to the 20th Century. Lassig Bridge & Iron Works was an early innovator of riveted spans, having constructed numerous types of riveted lattice truss spans during the 1880s and 1890s. Since the initial construction, the bridge has seen a number of alterations, including concrete repairs and rebuilding of the east approach. After abandonment of the railroad, the structure was sold to an adjacent property owner, and was to be removed for scrap. However, the Illinois Department of Natural Resources acquired the right-of-way and bridge, and converted it to the Rock Island Trail. As part of the conversion to a trail, a wooden deck and railings were installed, and the bridge was painted a grey color. Overall, the bridge appears to be in good condition, with no significant deterioration noted. The author has ranked this bridge as being moderately significant, due to the truss design.