BNSF East Branch Big Rock Creek Bridge

Located along US Route 30 west of Big Rock, this deck plate girder bridge carries the former Chicago, Burlington & Quincy Railroad over the East Branch of Big Rock Creek. The first bridge at this location was likely a timber pile trestle or truss. In 1891, the bridge would be replaced by a steel structure. This bridge consisted of a 50-foot through plate girder span, approached by a 25-foot deck plate girder span on either end, set onto stone abutments and steel caisson piers. The superstructure of the bridge was fabricated by New Jersey Steel & Iron Company, and the caissons were fabricated by the CB&Q shops at Aurora. As traffic on this line increased and became heavier, the bridge would require reinforcement. The bridge was strengthened in both 1926 and 1933. In 1937, the bridge would again be strengthened, and additional girders added. Bridge #167.34 near Juanita, Nebraska was constructed with an identical design in 1892, and all three spans were reused at this location. By the 1950s, the bridge was in poor condition. The caissons of the bridge were split and had to be banded, the steel was in poor condition and the bridge was too light for modern diesel locomotives. In response, the bridge would be replaced by the current structure in 1960.

Currently, the bridge consists of a 75-foot deck plate girder span, approached by a 39-foot deck plate girder span on either end. The bridge is set onto concrete pile substructures, which are capped with concrete. At this location, the railroad is aligned on a one-degree curve. To accommodate the curve of the bridge, all of the spans were constructed at a skew by cutting away portions of longer spans, which were reused from other locations. In addition, the bridge utilizes a slight superelevation, which pitches south. The main span of the bridge was originally constructed as an 80-foot deck plate girder span on the Casper Division at Bridge #312.99, north of Bonneville, Wyoming. This span had originally been fabricated in 1926 by an unknown contractor as part of a larger structure over an unknown creek. In 1950, the construction of Boysen Dam required the relocation of the railroad line in Wyoming, and the bridge spans would be removed and distributed for reuse. The approach spans were originally constructed as 40-foot deck plate girder spans as part of Bridge #29.82 across the Big Blue River, at Seward Nebraska. These spans had been fabricated in 1911 by the Pennsylvania Steel Company. That bridge was removed in 1952 on account of a realignment project. Both spans were likely shipped to a CB&Q yard, where they were stored until being reused here.

Both the 75-foot and 39-foot deck plate girders use a standard CB&Q design, and were rebuilt using bolts upon relocation. The bridge utilizes a ballast deck, constructed with timber. Ballast decks were standard for CB&Q bridges, as they reduced maintenance costs. Concrete piles became popular for substructure use in the early 20th Century, as they could be mass produced offsite and shipped to individual job sites. These piles could be installed by railroad crews, saving the cost of using contract labor. Railroads often reused steel bridge spans, as this method provided a cost effective way to repair and replace bridges without requiring new material. The CB&Q heavily reused bridge spans up until the BN merger. It is somewhat unusual to have installed secondhand material on a mainline, although the spans were clearly strengthened upon relocation. Overall, the bridge appears to be well maintained and in good condition. The author has ranked this bridge as being locally significant, due to the common design.