HR Green, the Iowa DOT, and HDR won the Honor Award in the ACEC National competition for the I-29 Improvements in Sioux City. A panel of nearly 30 judges selected the year’s most outstanding engineering accomplishments from nearly 175 entries. The project also won the Grand Place Award in the ACEC Iowa competition.

The I-29 project in downtown Sioux City modernized the existing 1960’s-era facility, which had deficient weaving sections, short ramps with abrupt entrances and exits, and horizontal and vertical curves that no longer met standards to squeeze four uncommon interchanges into 3.5 miles. This segment of urban freeway caused safety concerns for state officials, with an accident rate two to four times the statewide average.

The new $276 million project reduces and flattens the I-29 horizontal curves, improves interchange spacing, replaces 13 bridges, makes ramp configurations more consistent with driver expectations, and adds a mainline lane in each direction.

The project improved access to and through downtown for all motorists, enhanced access to the riverfront for pedestrians, and replaced thousands of feet of subsurface utilities. These changes have resulted in a facility that connects and unifies the City while improving system reliability and resiliency.