Duck Creek Swing Bridge

Located near Duck Creek Junction in Howard, this unique through plate girder swing span carries the former Chicago & North Western Railway mainline over Duck Creek. In the 19th and early 20th Century, Duck Creek was considered a navigable waterway as far inland as present-day Velp Avenue. The first bridge at this location likely consisted of a wooden truss swing bridge, constructed when the line was first built. In 1879, the main span was replaced by a 112-foot wooden Howe pony truss swing span, likely set onto a timber pile pier. In addition, the main span was approached by timber pile trestle spans, which were last renewed in 1894. In the first years of the 20th Century, the C&NW invested significant capital into this line, replacing aging timber bridges with stone and steel structures. Plans were developed for a new steel swing span in late 1903, and a new through plate girder swing span was installed on stone substructures in 1904. It is believed that the original northern approach consisted of timber pile trestle spans. This approach was replaced by a steel stringer span in approximately 1910, giving the bridge its present configuration. Currently, the bridge consists of a 113-foot rim-bearing through plate girder swing span, approached by a 29-foot steel stringer span. The entire bridge is set onto stone substructures.

The through plate girder span is one of two identical spans fabricated for the C&NW in 1904, with the other located at Oconto, Wisconsin. These spans both use a variation of a standard heavy through plate girder design, with massive girders, curved girder ends and a traditionally composed floor. The swing span uses a rim-bearing design, where the superstructure is placed onto a metal drum, which rotates on a roller nest set onto a geared track. The drum was turned by a gear system, which used the geared track to turn. The ends of the spans were lifted by a standard wedge-style block, which was controlled by an external metal rod placed onto small rollers. The swing span was operated by using a T-shaped key, which turned the gear system and activated the wedge end lifts. The approach span uses a standard design, with shallow steel stringers. Typical of swing spans, the center pier consists of a round design, while the approach pier uses a diamond shaped design. Both abutments use a standard design, with stepped wing walls extending diagonally from the structure. Stone for the substructures consists of a white limestone, likely quarried at the Duck Creek Quarry immediately south of this bridge. This quarry supplied high quality limestone for bridges and buildings throughout much of the eastern portion of the C&NW system. American Bridge Company fabricated the swing span at their Lassig Plant in Chicago, while the approach span was fabricated by an unknown contractor. The substructures were also constructed by an unknown contractor. Through plate girder spans were commonly used by railroads, as they were durable and easy to construct. These spans were also ideal for small swing spans, as they were simple to design. Since the initial construction, the bridge has seen a number of alterations. The northern pier has been repaired with concrete, and the original end lift mechanisms have been removed from the structure. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. A significant amount of strike damage is present on the swing span, likely due to a shifting load or derailment in the 20th Century. The author has ranked this bridge as being moderately significant, due to the swing design.