I-64 Bridge over Wabash River | Illinois Department of Transportation

Knight is currently providing Phase I and Phase II engineering services for the Illinois Department of Transportation for the 27-span dual structure carrying Interstate 64 over the Wabash River. Major rehabilitation and reconstruction of the dual bridge spans are required to address critical scour conditions caused by river realignment upstream. The Wabash River upstream the crossing of I-64 has a drainage area of over 29,000 square miles. A comprehensive hydrologic and hydraulic evaluation of the Wabash River at this location was completed to provide the basis for the design of a new bridge for I-64. The evaluation of the Wabash River watershed impacting the bridge included the detailed analysis of the gage record at Mt. Carmel, Illinois, the Flood Insurance Study for the Wabash River, the USGS peak flow frequency documentation and an independent study completed by the State of Indiana. A peak flow-frequency curve for the Wabash River at the I-64 bridge location was developed utilizing the gage record and the operational characteristics of several large dams in the upstream watershed. The generated peak flow-frequency data was used to develop a HEC-RAS model comprising a section of the Wabash River from 2 miles upstream of the bridge to 4 miles downstream of the bridge. Due to the unique site conditions and the extreme skew of the I-64 approach roadway in the Wabash River floodplain as well as the over 2mile width of floodplain and the presence of an overflow bridge opening, a divided flow approach was implemented with the water surface profile of the separate reaches being balanced for each event using an optimization scheme. An existing water surface profile condition was established using the HEC-RAS model and the results of the model were used as the basis to design a proposed waterway opening for the new I-64 bridge such that there would be no increase in flood heights caused by the new bridge. Additionally, because the Wabash River is experiencing severe channel migration in the reach of the river where the I-64 bridge is to be located, an evaluation of this ongoing process was completed and a design providing river training structures (spur dikes) to mitigate the recent channel migration and stabilize the Wabash River channel thorough the proposed bridge opening was completed.