KBSR Kankakee River Bridge (Aroma Park)

Located in the small town of Aroma Park, this large deck plate girder bridge carries the former Big Four over the Kankakee River. The first bridge at this location likely consisted of a wooden truss, set onto stone substructures. By the late 1870s or early 1880s, the bridge would be reconstructed with a three span iron truss bridge. This bridge consisted of three 156-foot pin-connected through truss spans, likely approached by trestle spans. In 1896, this bridge would be replaced by a large deck plate girder structure. This bridge would reuse the larger stone piers from the truss bridge, and smaller stone piers would be constructed between the larger piers. The superstructure would consist of six 78-foot deck plate girder spans. An additional 71-foot deck plate girder span was added to the north end of the bridge, and a 67-foot and a 27-foot span were added to the south end of the bridge. By the late 1910s, the bridge had become too light for traffic, and needed to be upgraded. Between 1917 and 1919, the current bridge would be constructed.

Currently, the bridge consists of nine deck plate girder spans, set onto stone and concrete substructures. The southern span (span #1) utilizes a 27-foot deck plate girder span, which has been strengthened with two additional girders. It is believed that portions of this span date to 1896, but it is unknown where the additional girders were reused from, or how old they may be. Span #2 consists of a 67-foot deck plate girder span, built in 1919. Spans #3, #4 and #5 all consist of 78-foot deck plate girder spans, constructed in 1917. Spans #6, #7 and #8 all consist of 78-foot deck plate girders, which have been strengthened with additional girders. These spans date to 1896, and the additional girders were likely reused from spans #3-#5. Span #9 consists of a 71-foot deck plate girder span, constructed in 1919. The piers of the bridge are mainly concrete, which replaced the original stone piers. The south abutment, south two piers, north pier and north abutment all reused the stonework from the previous bridge. These piers were heavily modified with concrete to accommodate the current bridge. Bethlehem Steel Company fabricated spans #2 and #9, and an unknown contractor fabricated the remaining spans. It is currently unknown if the concrete was constructed by contract or by railroad forces.

Railroads often were creative when upgrading bridges, looking to save costs wherever possible. This bridge is a great example of reducing the amount of new steel required, by strengthening existing spans with components of the same bridge which had been replaced. Adding additional girder likes was a common technique for railroads to strengthen spans, and the work was commonly done by company forces in the field. While many bridges reused piers from previous structures, it is unknown why this bridge replaced the stone piers. It is possible that the original stone piers had begun to fail, or were prone to causing ice jams. Numerous repairs have been made to the bridge since 1919, including the addition of timber helper bents at spans #3 and, #8 and #9, repairs to the piers, and a new concrete cap on pier #4. Overall, the bridge appears to be in fair condition, although a fair amount of deterioration is present in the substructures of the bridge. The author has ranked this bridge as being locally significant, due to the unique history and common design.