Osaugie Trail - Nemadji River Bridge

Located along US Highway 2 on the east side of Superior, this through plate girder bridge carries the former Northern Pacific Railway over the Nemadji River. The first bridge at this location was likely a timber truss swing bridge, constructed when the line was first built. During the early 20th Century, NP made a number of upgrades to this line, replacing timber bridges with steel. By 1904, the previous bridge had become too light for traffic, and would be replaced that year. The bridge consists of a 160-foot through plate girder swing span, set onto concrete substructures. Two spans of timber pile trestle were added to the west end and four spans to the east end of the bridge in 1953, giving the structure its current configuration. American Bridge Company fabricated the superstructure, while the W.S. Hewitt Company constructed the substructures. The abutments of the bridge appear to be set onto stone, which may be from the previous bridge. These abutments were likely buried between the 1904 construction and the 1953 additions.

The swing span uses a rim-bearing design, where the superstructure rests on a metal drum, which rotates on a nest of rollers. To operate the bridge, a hydraulic line raised each end of the bridge prior to rotating. The bridge was likely operated by using a T-shaped key to turn a series of gears. The superstructure uses a standard NP design, with heavily constructed girders, a standard floor and rounded girder ends. While the Nemadji River was open to commercial traffic when the bridge was built, it is believed that navigation closed on the Nemadji River in the early 20th Century. Since the river closed to commercial navigation, the bridge has been converted to a fixed span by removing the end rollers. Despite this, the remaining machinery remains intact. Through plate girder spans were commonly used by railroads, as they were durable and easy to construct. These spans also made good short length swing spans, as they were strong and required little maintenance. Today, the bridge is owned by the City of Superior, and the Osaugie Trail uses the bridge. Overall, the bridge appears to be in fair condition, with significant cracking and spalling noted to the substructures. The author has ranked this bridge as being moderately significant, due to the swing design.