BNSF Nemadji River Bridge (North)

View an article describing the collapse of the previous bridge

Located in Saunders, this large deck truss and deck plate girder bridge carries the former Great Northern Railway across the Nemadji River. The first bridge at this location consisted of a combination Pratt deck truss, approached by lengthy timber pile trestle approaches on either end. This bridge was constructed in 1892, and was set onto exclusively timber substructures. In May 1899, the bridge collapsed under the weight of a loaded ore train. All but a 300-foot section of the 1200-foot long structure collapsed. After the collapse of the previous bridge, it was decided to rebuild the structure with a permanent steel bridge. Originally, the bridge consisted of a steel deck truss span, constructed in 1928. In 1907, long deck girder viaducts would be added at each end. In 1913, the bridge was reconfigured, and additional deck girder spans were added to each end. The bridge was strengthened in 1928, and the west approach was replaced by concrete modular girder spans in 2009, giving the bridge its present configuration.

Currently, the bridge consists of a 150-foot, 6-panel, riveted Warren deck truss span, set onto stone piers. The east approach consists of 16 alternating 47-foot clear spans and 30-foot tower spans, with a 30-foot and a 40-foot span at the east end. The west approach originally consisted of a 47-foot, a 60-foot, a 30-foot, a 47-foot, a 30-foot and a 36-foot deck plate girder span. Presently, the west approach consists of 6 concrete modular girder spans, set onto steel pile piers. In addition, the 36-foot span adjacent to the deck truss has been shortened to 20 feet. The 20-foot span of the west approach and 40-foot span of the east approach were fabricated in 1913, while the remainder of the approaches were built in 1907. The east approach is set onto steel towers under the 30-foot spans, and is supported by concrete piers and pedestals. The deck truss span has been strengthened by adding an additional truss line and reconstructing the floor. An unknown contractor fabricated the initial construction, and another unknown contractor fabricated the third truss line and modified the span. An unknown contractor also completed the masonry substructures required for the bridge.

The truss span is heavily constructed, using a traditionally composed floor, large built-up members and heavy riveted connections. During the 1920s and 1930s, the GN strengthened numerous truss spans in a similar method as seen on this structure. The girder spans are traditionally composed, using heavy girders and an open deck. The pedestals use a combination of square blocks for a majority of the towers, and the main span piers use a traditional design. The towers are composed of solid beams, which are connected by plates instead of V-lacing. Deck plate girder viaducts were used where a large fill would not be practical. These spans were the most economical and most durable solution to lengthy, tall bridges. Warren trusses became popular in the early 20th Century, as they provided a more rigid and durable alternative to traditional pin-connected Pratt trusses. Since the 2009 reconstruction, some pedestals on the east approach have been repaired with a concrete encasement or epoxy. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being regionally significant, due to the size of the structure and the truss design.