Big Cut Road Overpass

Located southwest of Mt. Carroll, this historic pony truss bridge carries Big Cut Road over the BNSF mainline. During the early 20th Century, railroads throughout the United States made improvements to their property. Often, as part of double tracking or relocation projects, railroads constructed overpasses and underpasses to improve safety of pedestrians, wagons and later automobiles. Railroads often reused iron and steel bridge spans for these structures, as they provided a cost effective and sufficiently strong structure. In 1906, the CB&Q constructed a new overpass for Big Cut Road across their tracks near the station of Burke, where a siding was constructed that year. The overpass would reuse a 73-foot, 5-panel, pin-connected Pratt pony truss span, originally fabricated in 1872 for an unknown bridge. Upon relocation, the original floor of the truss was heavily altered with timber stringers, and the bridge strengthened. The truss span would be set onto timber pile piers, and approached by timber pile trestle spans. The approaches were replaced on 1950, giving the bridge its current configuration.

Pony truss spans like this were commonly used by railroads to cross moderate sized obstacles, as it was durable, easy to construct and provided a simple design. This particular design is one of several different designs used by the CB&Q during the 19th Century. The truss span utilizes laced vertical members, laced endposts and a laced top chord. The bottom chord is constructed of solid bars, while the diagonals are constructed of rods and turnbuckles. The upper angle connections are reinforced with riveted plates. The floor appears to have been heavily reconstructed, with timber stringers replacing the original stringers. The floorbeams retain empty brackets from the two stringers, and the original bottom lateral bracing remains intact. The truss span is likely fabricated from iron, and was most likely originally located along a mainline.

The truss span is among the oldest truss spans in the state of Illinois, and retains a high level of historic integrity despite alterations which exceed 100 years old. While hundreds of railroad spans were reused for roadways throughout the United States, most were replaced by the late 20th Century. Relatively few such examples remain, and even fewer exceptionally old spans remain. The bridge was closed to traffic in the mid 2010s, and has sat abandoned since. A contract for the demolition of this structure and a replacement bridge will be awarded in 2025. The author hopes that the truss span can be preserved, either as a pedestrian span, a driveway span or another use. The loss of this span would result in the loss of one of the oldest truss spans in Illinois, and one of few remaining railroad spans from the 1870s nationwide. With replacement of the stringers and deck, and repair of the floorbeams, the bridge could feasibly be reused to serve light traffic, either on a pedestrian trail, in a park or on a golf course. Overall, the bridge, particularly the timber approaches, appears to be in poor condition. Significant rotting, holes and deterioration can be seen throughout the timber. The iron truss and timber truss stringers appear to remain in fair condition, with some deterioration noted in the floorbeams. The author has ranked this bridge as being highly significant, due to the age and design of the truss span.