County Road G-76 over Interstate 35


County Road G-76 over Interstate 35


Iowa Department of Transportation


Warren County, Iowa

Project Details

Schemmer provided final bridge and roadway design with construction phase support services for the replacement of a structure on County Road G-76 over Interstate 35 and associated new I-35 access ramps. The structure consisted of a two-span, 212-foot by 41-foot Pretensioned Prestressed Concrete Beam (PPCB) bridge. Integral abutments founded on steel H-piling and a single T-pier strengthened for potential traffic impact were designed for the substructure elements. PPCB beams with an eight-inch cast-in-place concrete slab were designed for the superstructure elements. The bridge is superelevated to accommodate the horizontal curve on G-76. However, the bridge was designed on a tangent alignment with one-foot additional width to accommodate the horizontal curvature of the roadway. The project also reconstructs the entire interchange including four ramps, County Road G-76 and frontage roads. The roadway elements required construction phasing in order to maintain traffic. Multiple culvert extensions and new culverts were also designed.