Benesch was charged with designing a sustainable and economical replacement structure for the deteriorated Wabash River Bridge, a 12-span, narrow steel through truss structure. The project area is a harsh, ever-changing environment, involving extraordinary complexities and posing a number of design and constructability challenges, such as liquefaction and scour due to unpredictable flooding from the river, the presence of migratory and endangered species and seismic activity on the New Madrid Fault. In addition, the structure also connects two states—Illinois and Indiana—meaning the structure’s design had to conform to all roadway and structure standards for both state Departments of Transportation.
After conducting a bridge type study, including value engineering workshops, Benesch designed a 1,075-foot five-span hybrid steel girder unit with a foundation to withstand seismic activity, liquefiable soils, 10 to 100-foot deep bedrock and a riverbed susceptible to scour. The bridge also includes three units of long-span PPC Bulb-T girders with foundations addressing the same issues.
The completed structure includes widened shoulders for safe bicycle access while incorporating several economical design elements, as well. The new bridge was designed so future concrete deck replacement would allow two lanes of traffic to remain open during construction, a very important consideration since a detour would be in excess of 40 miles.