UP Chariton River Bridge

View an article discussing the construction of this line (digitized by Google)

Located south of Chariton, this deck plate girder bridge carries a former Chicago, Rock Island & Pacific Railroad (Rock Island) mainline over the Chariton River. Little is known about the history of this structure. When the Rock Island constructed the St. Paul & Kansas City Short Line between 1911 and 1913, it is thought that this was one of a handful of steel bridges constructed along the line. Initially, this bridge consisted of a single deck plate girder span, set onto concrete piers and approached by timber pile trestle spans at either end. Timber approaches were commonly used to allow approach embankments to settle without damaging the steel and concrete portions of the bridge. The intention was to either fill or replace these approaches with steel spans as soon as practical. By the late 1930s and early 1940s, the embankments had settled enough to allow for permanent spans to be installed. In approximately 1940, the approach spans were reconstructed with secondhand deck plate girder spans, giving the bridge its present configuration. It is unclear if the approaches were constructed as part of the same project, or were built at different dates. Currently, the bridge consists of a 100-foot deck plate girder span, approached by a 70-foot deck plate girder span on the south end and a 35-foot deck plate girder span on the north end. The entire bridge is set onto concrete substructures, which may have been constructed at different times. The main span uses a standard design, consisting of two very heavy plate girders and a timber ballast deck. It is believed that this span was fabricated in 1912, and is original to this location. The south span was originally fabricated in 1898 for use at an unknown location. This span uses a similar design to the main span. The north span was originally fabricated in approximately 1900 for use at unknown location(s). This span follows a "twinned" design, with four shallow plate girders and a ballast deck. It is unclear if the span was twinned upon being relocated here, or if it was previously twinned. The piers follow a standard design, and consist of large rectangular shaped structures founded on timber piles. This design of pier is slightly different than other bridges along this line, which use a diamond shape. The abutments also use a standard design, with the south abutment using a "U" shaped design and the north abutment having short sloped wing walls. American Bridge Company fabricated the center span, while the south span was fabricated by the King Bridge Company and the north span was fabricated by an unknown firm. It is believed that J.C. Dunn constructed the piers, while the substructures were constructed by unknown contractor(s). The different types of abutments could possibly suggest that the approaches were installed at different times. Railroads often reused steel and iron spans, as it provided a cost effective way to upgrade bridges without requiring large amounts of new material. Twinning girder spans was a popular technique to strengthen existing spans, while reusing material already on hand. The Rock Island undertook several programs in the 20th Century to strengthen mainline bridges using this method. Deck plate girder spans were popular for railroad use, as they were durable and easy to construct. Since the approaches were reconstructed, the bridge has seen no significant alterations. Today, the bridge remains in use as part of a Union Pacific Railroad mainline. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked the bridge as being locally significant, due to the common design.