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Camanche 9th Street Bridge Replacement

Challenge

Originally built in the 1920s, the Camanche 9th Street single-span truss bridge was nearly 100 years old and very narrow, making it challenging for oncoming traffic to pass. Due to its age, the bridge was also suffering from structural deficiencies.
 

Solution

Shive-Hattery recommended a full bridge replacement, which called for removing the existing structure and constructing a new, 30-foot-wide, 80-foot-long, three-span continuous concrete slab bridge.
 
The bridge spans Rock Creek, but sits close enough to the Mississippi River that it is impacted by flooding. Design requirements called for the bottom of the bridge to be above the 100-year floodplain, which would have required raising the bridge by at least six feet. Knowing that this would have major impacts on surrounding properties (as well as very high costs), Shive-Hattery conducted a no-rise hydraulic analysis to show that the new bridge design – which was higher, but not as high as the 100-year floodplain requirements – wouldn’t impact area flooding. As a result, Shive-Hattery applied for No-Rise Certification, which indicates that the bridge will not impact pre-project base flood elevations, floodway elevations, or floodway widths.
 
Because surrounding wetlands were impacted by raising and widening the bridge, Shive-Hattery conducted wetland mitigation, adding vegetation away from the project to replace what was removed to make way for the new bridge.
 
The project also included design for approximately 700 feet of approach roadway to smoothly connect the bridge to the existing 9th Street roadway. Additional services included topographic and hydraulic surveys, and hydrologic and hydraulic modeling for permitting through the Iowa Department of Transportation and the Iowa Department of Natural Resources.
 

Impact

Replacing its original, 1920s structure with a new three-span continuous concrete slab bridge makes the Camanche 9th Street bridge safer for drivers. It will remain structurally sound, eliminating the City of Camanche’s previous concerns about potential problems. Maintenance costs will also be lower, since bridge repairs won’t need to be made as often.
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