IIW led the emergency replacement of the North Cascade bridge after it was washed out by a summer storm in Dubuque, Iowa. IIW’s engineering team conducted a hydrologic and hydraulic analysis to determine the optimal type, size and location of the bridge over South Fork Catfish Creek.
The mapped floodplain and detailed flood study led IIW to raise the bridge and roadway by 5 feet. The completed bridge includes a 34-foot roadway and an 8-foot sidewalk on one side. A 181-foot long four-span continuous concrete slab structure, the bridge sits a 9.5-degree curve with a 15-degree skew.
IIW worked closely with the Iowa Department of Transportation and Federal Highway Administration, which provided the funding. IIW prepared multiple cost estimates for alternatives in the roadway alignment to allow a final alignment and type to be selected.