Centennial Bridge traffic study and rehabilitation

Project Summary

Hanson was chosen by the city of Rock Island to conduct a traffic study of the Centennial Bridge in Rock Island, Ill.  The four-lane toll facility spanned the Mississippi River, connecting downtown Rock Island to downtown Davenport, Iowa.  The city of Rock Island and state of Illinois were considering removing the toll facility as a means of creating additional traffic capacity across the river in the hope of alleviating the need to make improvements to the Interstate 74 structures which were nearing capacity. 

If the tolls were to be removed from the bridge, the city of Rock Island would no longer have the means necessary to pay for the structure’s maintenance.  Therefore, the state of Illinois would need to assume ownership of the structure and adjoining roadways if the project were to move forward.  Before agreeing to the change, the Illinois Department of Transportation required the city of Rock Island to determine what improvements were needed to accommodate the projected increase in bridge traffic. 

Hanson conducted a traffic study that developed 2,020 turning-movement volumes for critical city-street intersections that served both Rock Island’s and Davenport’s bridge approaches.  Based on these projections, Hanson identified the improvements needed to help the city’s local street system safely accommodate a sudden growth in average daily traffic and enhance peak-hour traffic flow over the bridge. 

Additionally, Hanson prepared plans and specifications for the reconstruction of the local road network on each side of the Centennial Bridge connecting Rock Island to Davenport. These plans included removing and replacing pavement, subbase, and curb and gutter; constructing storm sewers and drainage structures; and installing street lights and custom electrical components for landscape features intended to create a gateway into each community.

This project involved coordinating the work of six design firms and interacting with five government agencies. Hanson also worked to build consensus with all agencies within a short time frame.