Rockford Trail Bridge

Located immediately downstream of the former Chicago & North Western Railway bridge in Rockford, this large through truss bridge carries the former Chicago, Burlington & Quincy Railroad over the Rock River. The first bridge at this location was planned in the 1870s, and in 1874; the C&I awarded a contract to local stonemason H.T. Smith for the construction of stone bridge piers for a new bridge across the Rock River. Work on the piers was reportedly completed in 1874 or 1875, although the piers remained unused for several years. In 1882, the Chicago, Milwaukee & St. Paul Railway (Milwaukee Road) and the CB&Q reached a deal to allow the Milwaukee Road to access terminals in Rockford, and a new bridge would be constructed on the unused piers. The first bridge consisted of five 150-foot covered wooden Howe trusses, approached by smaller uncovered wooden trusses.

In 1896, the bridge received a major overhaul, and the smaller wooden truss spans would be replaced. On the west end of the bridge, two 103-foot pin-connected Pratt through trusses would be installed. These spans were likely fabricated in the 1880s, and were reused from an unknown location. On the east end, two 63-foot deck plate girder spans would be fabricated by King Bridge Company, and installed on the existing stone piers. By the 20th Century, wooden trusses had become obsolete for railroad use. As a result, the CB&Q replaced the bridge with the current through truss spans in 1929. These truss spans were originally built in 1898 by King Bridge Company, and served as a crossing across the Illinois River at Beardstown, Illinois. Upon relocation, the spans were shortened to fit on the existing stone piers, which were capped with concrete. Further repairs were made to the bridge in 1944, when concrete aprons were added around the base of the piers. In 1951, the two 103-foot spans would be removed, and pier #7 converted to the new west abutment. One of these spans was scrapped, the other was salvaged for reuse at an undisclosed location. The most recent alteration to the bridge came in approximately 2000, when a modular concrete girder span was installed on the east end, and the eastern pier reconstructed. These alterations were made to revise the elevation of the tracks at this end of the bridge.

Currently, the bridge consists of five 150-foot, 7-panel, pin-connected Pratt through truss spans, approached by two 63-foot deck plate girder spans and a short concrete span on the east end. The eastern truss span was shortened from a 199-foot span upon relocation, while the remaining spans were shortened from 155-foot spans. These trusses utilize a design standard to the CB&Q during the late 1890s and early 1900s, using pinned connections, laced vertical members and the standard CB&Q portal. The end panel lower connections feature two pinned connections, a feature occasionally seen on bridges from the 1880s and 1890s. This particular portal bracing design utilizes a shallow bar, with angular heel bracing, and the sway bracing utilizes a standard bracket style bracing. This particular portal design appears to have been a CB&Q standard, and was used on truss bridges from the 1890s until the 1930s. The eastern truss utilizes an X-frame portal bracing with laced sway bracing, likely due to its longer original length. The deck plate girder spans utilize a "fishbelly" or variable depth design, a design which was occasionally used to avoid significant alterations to existing substructures.

Railroads often reused steel and iron spans, as it provided a cost effective way to upgrade bridges without requiring new bridge material. The CB&Q extensively relocated spans, often moving mainline bridges to branch lines or reusing them as roadway overpasses. Typical of branch line bridges, this structure was constructed at different times, and has seen numerous changes since the initial construction. The railroad across this bridge was abandoned in 2010, in conjunction with the reconstruction of the nearby Morgan Street bridge. The City of Rockford acquired the bridge, and the structure was retrofitted with a concrete deck and railings for pedestrian use in 2016. Today, the bridge continues to serve pedestrians, and is a popular feature along the Rock River in Rockford. Overall, the bridge appears to be in good condition, with no significant deterioration noted. The author has ranked this bridge as being regionally significant, due to the history, design and reuse of spans from another location.