IL 97 over Spoon River

The bridge carrying IL 97 over Spoon River was originally constructed in 1926.  Various repairs had been completed throughout the years, but the future use of the bridge was in question because of its condition.  Oates Associates conducted a condition analysis, and a full replacement of the 15-span structure was recommended.

A hydraulic analysis was performed for the structure to determine replacement options.  Runoff was calculated and water surface profiles were computed for natural, existing and proposed conditions.  Scour analyses for the 50, 100 and (overtopping) 300-year storm frequencies were performed.  To improve the hydraulics of Spoon River and meet created head and clearance requirements, Oates Associates designed a 7-span structure consisting of reinforced concrete deck on steel plate girder superstructure.