The I-74 Mississippi River crossing is a vital interstate connection facilitating the movement of people, goods and services across a major waterway between Iowa and Illinois. So, when the existing bridge could no longer adequately serve growing traffic volumes, regional partners including the Iowa Department of Transportation and Illinois Department of Transportation set out to provide a solution that would not only carry the estimated 80,000 vehicles per day, but serve as a signature structure for the region.
The Departments’ vision would rise 245 feet above the river and take the shape of twin, true-arch bridges that now provide an iconic structure and essential mobility solution for the community and daily commuters. Serving as an extension of Iowa DOT, HNTB provided construction engineering and inspection (CE&I) services for the eastbound and westbound river bridges, Iowa-side viaduct and roadway approaches, as well as local road connections. Services included engineering, inspection, document control, quality assurance and, as the complex project unfolded, much more.
Each bridge features a 72-foot roadway and a 795-foot basket-handle, true-arch span over the navigation channel. Fourteen parallel flange-welded plate girder approach spans create a total bridge length of 3,440 feet from the Illinois abutment to the transition pier on the Iowa bank.
Other features of the project include:
- Four traffic lanes with full shoulders in each direction
- A 14-foot-wide multiuse path connecting trail systems in Bettendorf and Moline
- Glass oculus embedded in the scenic overlook’s multiuse path
- Dramatic LED lighting
- ADA accommodations
As an extraordinary structure that has dramatically reduced congestion and improved safety, the I-74 Mississippi River Bridge has provided a transportation solution that will help propel regional growth for many years to come.