I-74 Corridor Final Design, Central Section

I-74 Corridor Final Design, Central Section


WHKS was a core part of the consultant team selected by the Iowa Department of Transportation (Iowa DOT) and the Illinois Department of Transportation (Illinois DOT) to provide final design services for improvements along the 7.8 mile I-74 corridor in the Quad Cities. The work included the final design of the Central Section, which is the area just south of Lincoln Road in Bettendorf, Iowa to just south of 12th Street in Moline, Illinois. The project widened the roadway to three lanes in each direction, replaced the bridge over the Mississippi River, and reconstructed two interchanges. 

WHKS’ role involved final bridge, drainage, and roadway design. WHKS produced several construction packages with an emphasis on two issues: maintaining traffic flow for both mainline and local roads and maintaining drainage and other utilities during staged construction.

Bridge design by WHKS included the Iowa Viaduct Bridges on mainline I-74 on approach to the main spans of the new Mississippi River crossing. These are curved and straight continuous welded steel girder bridges (westbound to be built by staged construction) and include:

  • Eastbound – 2271′-6″ x variable width (four units)
  • Westbound – 2274′-7″ x variable width (four units)

In addition to final design activities, WHKS was involved in corridor-wide coordination activities including project management, project advisory committee participation, traffic management and construction staging.


  • Final roadway, drainage, and bridge design
  • Local road design
  • Traffic control and staging plans


The I-74 bridge project was 20+ years in the making after the existing bridge was declared outdated and dangerous. The Mississippi River is one of the most important waterways in the world and being able to cross it safely, allows residents and tourists to travel from state to state for generations to come. The new facilities provide opportunities for the economies of Iowa and Illinois and improves regional and global options for moving goods produced in each state.