Windom Railroad Bridge

a collection of images of the derailment that destroyed the previous bridge

Located in Windom, this quadrangular lattice through truss bridge carries the former Chicago, St. Paul, Minneapolis & Omaha Railway mainline over the West Fork Des Moines River. The first bridge at this location was likely a timber truss bridge, which was constructed when the line was first built. In 1883, the bridge would be rebuilt with a two span iron quadrangular lattice through truss bridge, set onto stone substructures. The bridge followed a standard design for the era, with light members and a lattice portal with solid center plate. On September 22nd, 1899, a train derailed on the bridge, destroying both truss spans. A temporary trestle would be built and used until the current bridge was constructed in 1900. The current bridge consists of a 157-foot and a 100-foot quadrangular lattice through truss span, set onto concrete and stone substructures. The bridge originally featured four 40-foot deck plate girder spans on the south end, but these were filled prior to 1938. Lassig Bridge & Iron Company fabricated the steel, while the substructures were constructed in 1882, 1900 and c. 1930by unknown contractors.

The truss spans follow a standard design for the era, with heavy members, a standard floor and a portal bracing unlike similar spans from this era. The top chord consists of a built-up beam, covered by a solid plate on top and V-lacing on the bottom. The bottom chord is composed of two channels, which are connected by thin plates on the top and bottom. The endposts use a similar design to the top chord, with plates on the front and V-lacing on the back. The outer compression members are composed of solid beams, while the inner compression members use V-laced beams. The tension members are all composed of L-shaped bars. The portal bracing uses a double intersection lattice design, and is constructed of bars. In addition, an angular heel brace connects to the endposts. The sway bracing is constructed of V-laced beams and the upper lateral bracing is composed of square bars. The floor is composed of two plate girder stringers, connected to plate girder floorbeams. The north abutment and pier follow a standard design, with stepped wing walls at the abutment and a diamond shaped pier. Both the north abutment and pier have been encased with concrete. The south abutment originally was a diamond shaped pier, but has been retrofitted into an abutment with concrete additions.

Although the lattice truss design was popular in Europe, few American railroads utilized the design. While Union Pacific Railroad, the Chicago, Rock Island & Pacific Railway and a handful of eastern railroads utilized the design to various extents, no railroad constructed as many lattice truss bridges as the Chicago & North Western Railway and their subsidiary Omaha Road. Throughout the 19th Century, the Omaha Road used this truss design nearly exclusively. Although lattice trusses were not popular with American railroads after the 1880s, the C&NW and Omaha Road relied heavily on this design, as it had proven to be resilient towards derailments and damage. The main drawback of the design was the unpredictable nature, as the structure was not statically determinant. Since the initial construction, the bridge has seen a number of alterations, including the filling of the south approach and strengthening of the trusses. Several members on the southern truss were replaced by similar high strength steel members in the 20th Century. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The rehabilitation of the bridge also appears to have lengthened the life of the bridge. The author has ranked this bridge as being moderately significant, due to the truss design.