In a joint venture, the Illinois Department and Transportation (IDOT) and Iowa Department of Transportation (Iowa DOT) have unveiled the $237 million preferred alternative for replacing the Centennial Bridge. While the project is firmly in the design phase, the official construction date has not yet been released.
The departments announced their preferred alternative selection during an open house event on Oct. 21. Officials determined that option E2 was superior to E7 and will now advance the project into the next stages of Phase 1. The next steps will consist of completing an environmental review, continuing overall engagement and reviewing public input before moving into final design.
While the current 85-year-old bridge has been rated in fair condition, its overall useful lifespan has reached its end. Workers have been completing patch jobs and repairs for years, which while able to extend its operability has turned the structure into an investment sink. Full replacement will ensure the corridor between Davenport, Iowa, and Rock Island, Ill., remains safe and cost-effective.
The preferred alternative will build a replacement bridge immediately west of the existing structure. By maintaining the familiar position, the departments ensure residents won’t be required to change their commutes while maintaining a similar skyline profile and connecting the downtown areas.
The new bridge configuration notably hit every purpose and need laid out in the project. The structure will incorporate features needed for long-term sustainability, ensuring residents have reliable connectivity and transportation options for decades to come.
In addition, the design removes or reduces under-designed or non-redundant features that affect maintenance burdens and load posting. The project will address unsafe roadway geometric deficiencies and enhance pedestrian and bicycle connectivity across the Mississippi River.
While the overarching bridge design will be largely similar to the original layout, the departments are evolving the structure to comply with modern standards. While travel lanes will remain 11 feet wide, the new bridge will be overall wider with eight-foot shoulders to provide more space for all travelers.
The design includes a 4-foot striped median as a better alternative to the original raised median. The project will incorporate a multi-use path with a 12-foot minimum width for non-motorized travelers. The departments are also planning to build connecting sidewalks and multi-use paths between the bridge and downtown areas.
The E2 design was selected for a number of reasons over the E7 option. Among these, the preferred alternative will have the least amount of property impacts and right-of-way acquisitions needed to facilitate construction. The option also has a significantly lower construction cost compared to its $295 million E7 alternative.
Following project completion, the existing Centennial Bridge will likely be removed. However, the bridge is eligible to be listed on the National Register of Historic Places, which may preserve the structure as a regional landmark.
Photo courtesy of Illinois Department of Transportation and Iowa Department of Transportation
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