UP Elkhorn River Bridge (Arlington)

Located west of Arlington, this quadrangular lattice through truss bridge once carried the Union Pacific Blair Subdivision over the Elkhorn River. The first bridge at this location was likely a wooden through truss. In 1902, the bridge would be replaced with a 160-foot riveted quadrangular lattice through truss span. It is unknown if the truss was originally set onto concrete piers, or if it utilized stone piers at first. By the time of documentation, the stone piers were long disused and in poor condition, behind the concrete piers. The bridge originally featured a 24-foot deck plate girder span, although this was later replaced with timber pile trestle spans. The approaches of the bridge were again reconstructed in approximately 1980, when two 45-foot steel stringer spans were installed on the west end of the bridge, and one 30-foot span installed on the east end. The quadrangular lattice design was the favorite truss design of the C&NW. While a few other railroads, such as Union Pacific, Rock Island and Erie all used the design at various times, no railroad relied on the design as much as the C&NW. Between 1878 and 1930, most trusses constructed by the C&NW were of the quadrangular lattice design. This span is typical of a turn of the Century design, as evidenced by the heavy members and A-frame portal. Later repairs were also made to the truss, including replacing a large number of rivets with high strength bolts. At the time of documentation, the bridge appeared to be in fair to good condition, with no significant deterioration noted. The bridge was replaced by a new bridge on a new alignment upstream in 2022. Union Pacific has spent significant capital upgrading this route, and this bridge was one of the last major chokepoints. The author has ranked this bridge as being moderately significant, due to the truss design.