Elmen Park Railroad Bridge

Located in Sioux Falls, this quadrangular lattice through truss bridge carries the former Chicago, St. Paul, Minneapolis & Omaha Railway (Omaha Road) across the Big Sioux River near Elmen Park. The first bridge at this location was likely a timber pile trestle or wooden truss bridge, constructed when the line was first built. In the late 1880s and early 1890s, the Omaha Road invested significant capital into this line, replacing aging timber bridges with stone and iron structures. In 1892, the original wooden bridge would be replaced by the present structure. The bridge consists of a 100-foot, riveted quadrangular lattice through truss span, set onto stone substructures and originally approached by timber pile trestle spans on the east end. The main span uses a standard design for the era, including a pedimented portal bracing with decorative heel bracing, a combination of built-up and solid members and a traditionally composed floor. Typical of this type of span, the bottom chord is constructed of two parallel beams. The endposts and top chord are also composed of built-up beams, with the endposts using an X-lacing on the back side while the top chord uses thin plates spaced throughout the member. X-laced members are used for the compression members near the ends of the truss, while inner compression members are constructed of V-laced beams. The tension members are exclusively constructed of L-shaped bars. The floor follows a standard design, with two plate girder stringers and plate girder floorbeams spaced throughout the structure. The portal bracing uses a typical lattice pedimented design and solid triangular heel bracings with flower-shaped cutouts. Lassig Bridge & Iron Works fabricated the main span, while the piers were constructed by James McClure.

This type of truss design is relatively uncommon throughout the United States. However, a few railroads preferred the design, such as the Chicago, Rock Island & Pacific Railway (Rock Island), the Chicago & North Western Railway (C&NW) and the Omaha Road. Spans constructed in the early 1880s for the Omaha Road featured an arched and pedimented lattice portal bracing, light sway bracing and laced members. The second generation was nearly exclusively constructed by Lassig Bridge & Iron Works between 1884 and 1900, and featured heavier members and a pedimented portal bracing. While the design fell out of favor for the Rock Island and Omaha Road around the turn of the 20th Century, the design remained popular with the C&NW into the 1920s. The discontinuance of the lattice design is one of the few examples of the Omaha Road and C&NW bridge engineers having differing thoughts on bridge designs. This particular span uses a design typical for the second generation of quadrangular lattice through trusses. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The truss was repaired with high strength bolts in about 2010, and the original approach was replaced in 2024. The author has ranked this bridge as being moderately significant, due to the truss design.