Carroll County Road 321 Overpass

Located between Bosworth and Carrollton, this small pony truss bridge once carried Carroll County Road 321 across the BNSF mainline. As the ATSF double tracked the line between Chicago and Kansas City, many grade crossings were removed, either by constructing an underpass or an overpass. At this location, the railroad is set into a deep cut, necessitating an overpass. This bridge was built in 1911, reusing a 83-foot, 5-panel pin-connected Pratt pony truss, set onto concrete piers. In addition, the bridge was approached by timber pile trestle spans on either end. It is currently unknown where the truss span may have been reused from, but it appears the span was built in approximately 1885. It appears that the truss may have been constructed of iron, as opposed to steel. The members of the truss are lightly constructed, with light V-lacing on the upper chord and vertical members. The lower chord was constructed of a pin and eyebar construction, typical of 19th Century trusses. The bridge was heavily altered in 1929, when the floor system was reconstructed with new wooden stringers. In addition, outriggers were added at the vertical members to stabilize the truss.

Railroads often reused steel and iron spans for roadway use and for overpasses. This allowed the railroad to save costs on ordering new spans, and minimized the engineering required, as a railroad span could safely handle roadway traffic. Occasionally, spans were moved short distances from their original locations and received little alterations. Other spans were constructed using spare parts, and were extensively rebuilt to serve roadway use, as it appears this span was. While hundreds of these overpasses once existed throughout the United States, the number has begun to dwindle in recent years. In particular, these spans are often too narrow, have unsuitable decks and have little documentation about the condition or the history of the spans. In 2020, BNSF removed this bridge, likely to improve horizontal clearance below the structure. It is believed that the span was scrapped upon removal, and no replacement was constructed. The author hopes that removal of these bridges is advertised in the future, as it allows agencies and property owners instigate the feasibility of acquiring a span. Many of these spans could feasibly be reused for private road use or for pedestrian use. While larger projects often have a formal notice of work and advertisements to acquire a span, this bridge was not advertised. Overall, the bridge appeared to be in fair to poor condition at the time of replacement, with deterioration to the deck and substructures. The author has ranked this bridge as being regionally significant, due to the older age, reuse and preservation.