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I-74 Mississippi River Bridge – Illinois Approach Corridor

The I-74 corridor in the Quad cities is approximately 7 miles long and crosses the Mississippi River between Bettendorf, Iowa and Moline, Illinois. Modjeski and Masters, as part of the Alfred Benesch team, was chosen to design multiple Illinois approach structures.

M&M completed a VE Study, revised the Phase I Type, Size and Location plans for the grade separation structures, and provided final design for 5 interstate overpass bridges and 15 retaining walls. 

The structures at 19th Street carry I-74 WB, EB, and Ramp 7th-A over four separated lanes of traffic and a pedestrian sidewalk on 19th Street. The new structures consist of three, three-span continuous steel plate girder structures with straddle piers to span the roadway which is skewed at 65 degrees. The stub abutments, retained by MSE walls, and the straddle piers are founded on h-piles. 

The structures at 12th Avenue carry I-74 WB and EB over two lanes of traffic and a pedestrian sidewalk on 12th Avenue. The new structures consist of two single span steel girder structures skewed at 18 degrees. The stub abutments retained by MSE walls are founded on h-piles. The design was complicated by a noise wall required on the exterior barrier of the EB structure.

The retaining walls consist of 10 MSE walls and 5 soldier pile walls.  Multiple walls included necessary ground improvements. The design was also complicated by 5 temporary retaining walls, a three year construction staging sequence, and coordination with multiple disciplines and entities.

Bridge Geometry
MSE Retaining Walls 10 walls–6,100’
Soldier Pile Retaining Walls 5 walls-3,900’
Temporary MSE Retaining Walls 5 walls – 350’
Structures range from 385’ to 82’