CN Boyer River Bridge #1

Located in a rural area between Boyer and Deloit, this through and deck plate girder bridge is the first bridge carrying a former Illinois Central Railroad mainline over the Boyer River. When the railroad originally was constructed, the first bridge at this location consisted of a 75-foot and two 30-foot deck plate girder spans, set onto concrete substructures. The Boyer River had long experienced severe floods, and by the early to mid-20th Century it was decided to channelize the river. In 1954, the bridge was significantly rebuilt by replacing the center span with a through plate girder span to improve clearance underneath. As part of the work, the substructures were heavily modified and the entire bridge was rehabilitated with minor repairs and new paint. Currently, the bridge consists of a 77-foot through plate girder span, approached by a 30-foot deck plate girder span on either end. The entire bridge is set onto concrete substructures, and is located on a 2-degree curve. American Bridge Company fabricated the center span, while American Bridge Works fabricated the approach spans. George B. Swift Company constructed the original substructures, and it is unclear if the 1954 alterations were made by railroad company forces or by an unknown contractor.

The center span follows a standard design for the era, with two heavy plate girders, square girder ends and a standard floor. While welded and bolted construction was becoming more common by the 1950s, this span still is heavily riveted and uses a largely traditional design for the early 20th Century. The approach spans also use a standard design for the era, with two light plate girders and an open deck. Originally, the piers consisted of rectangular structures founded on timber piles. During the 1954 reconstruction, they were rebuilt with concrete additions on either side and a concrete riser to fit the through girder span. Both abutments use a standard U-shaped design with no wing walls, typical of some bridges along this line. The abutments have also been modified with concrete additions, likely indicating the bridge was also raised in 1954. Through plate girder spans were popular for railroad use, as they were durable and easy to construct. Since the 1954 reconstruction, the bridge has seen no significant alterations, and remains in regular use. 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.