UP 35th Street Bridge

Located in Council Bluffs, this unusual deck plate girder bridge carries a former Union Pacific Railroad mainline and yard over 35th Street. Much of the history of this bridge is unclear. It is believed the first bridge at this location was constructed in 1900, and consisted of a deck plate girder bridge constructed for two tracks (now the northern tracks, #6 and #7). In approximately 1910, the bridge was widened and three additional tracks were added (now the southern tracks, #1, #2 and #3). Due to the expansion of the Pacific Fruit Express icing facility near this bridge, the bridge was expanded again in 1921, when tracks #4 and #5 were added to the bridge, giving the structure its present configuration. Currently, the bridge consists of a 43-foot deck plate girder main span, approached by a 23-foot deck plate girder span on either end (tracks #6 and #7) or a 28-foot deck plate girder span on either end (tracks #1 through #5). The bridge is set onto a variety of steel bents, stone footings and concrete abutments. It also appears that several components of the bridge may have been reused here at other locations. Due to the various expansions, the bridge has a number of different designs.

Tracks #1 and #3 are virtually identical, with the girders using a consistent depth and standard design. The interior of the girders are connected with standard X-frames and lateral bracing. The bents consist of V-laced beams, formed into an A-shape. Track #2 consists of a very unusual design, with the main span significantly overhanging the bents on either side. The ends of the girders are rounded, and additional triangular plates have been added at the ends. Inside the main span, the interior bracing consists of light X-frame braces and a light lateral bracing on the top. The approach spans use shallow girders, which have no internal bracing and are stacked on blocks at the ends. The bents are considerably lighter than the other tracks of the bridge, and are constructed of light V-laced beams, constructed in a rectangular shape. It appears the main span was likely fabricated in approximately 1890, likely for use at an unknown location. It also appears that the approach girders and bents were fabricated around the same time and salvaged from unknown structure(s). Tracks #4 and #5 are also vertically identical, consisting of similar spans to tracks #1 and #3. The bents for these tracks consist of four X-laced columns, connected by transverse bracing at the bottom, middle and top. A number of additional repairs have been made to the bents, including new structural members. Tracks #6 and #7 also use a standard design, with three girders of the same depth. The X-frames and lateral bracing is slightly lighter than adjacent spans. The bents are composed of four solid columns, connected by transverse bracing at the top, bottom and middle.

Unique to this bridge, the abutments use a design giving the bridge two different lengths. Tracks #6 and #7 are slightly shorter than the remaining tracks, and the abutments jog in between track #5 and track #6. Both abutments use a standard U-shaped design, and do not use wing walls. The bents for tracks #1 through #5 are set onto a continuous concrete wall, which appears to have been constructed at one time. The bents for tracks #6 and #7 are set onto a stone footing, constructed of a tan limestone. Lassig Bridge & Iron Works fabricated the superstructure for tracks #6 and #7, while unknown contractors fabricated the remaining superstructure. It is unclear if the substructure was constructed by railroad company forces, unknown contractors or a combination of both. Deck plate girder spans were commonly used by railroads, as they were durable and easy to construct. Deck girder spans with steel bents were popular for both tall and long bridges, as they provided the most cost effective design. Other than the various expansion projects, the bridge has seen only minor repairs, including various concrete repairs. Today, the bridge remains in regular use, with five of the seven tracks remaining active. Overall, the bridge appears to be in fair to good condition, with no significant deterioration noted. The author has ranked this bridge as being moderately significant, due to the unusual combination of similar spans and various build dates. In particular, the center span of track #2 is extremely unique.