Precast Concrete Products Accelerate Highway 20 Construction in Iowa

Bob Schaffler & Bill Adams

Expansion of U.S. Highway 20 in northwest Iowa from two lanes to four lanes had been planned for decades. The cost to widen the highway, however, was a reason for the delay of construction. After a letting of nine miles in 2014—won by C.J. Moyna & Sons Construction of Elkader, Iowa—Gov. Terry Branstad signed a $0.10-per-gallon increase to the fuel tax on May 25, 2015. The new tax revenue of approximately $200 million accelerated widening of the remaining 37 miles of the Highway 20 expansion. Specifications allowing precast concrete boxes and pipe for the remaining lettings expedited construction so that the widening could be completed as planned. The approximate cost would be $290 million, which would include grading and paving, precast boxes, round pipe and precast arches for culverts.

The Solution

The Concrete Pipe Assn. of Iowa had been meeting with the Iowa Department of Transportation (IDOT) to draft specifications and standards for precast concrete for as long as the widening was being planned. Even though IDOT specified portions of the final alignment of the project (some long outlet flumes and transition sections) as cast-in-place only, most of the drainage structures were specified allowing precast alternates. IDOT’s chief engineer determined that precast box culverts would be conducive to an accelerated construction schedule. Ames Construction of Burnsville, Minn., Hancock Concrete and IDOT worked to finalize a sound construction strategy.

Precast concrete boxes of various sizes have been shipped to culvert construction sites along 37 miles of Highway 20.

The initial nine-mile grading project had specified cast-in-place only for nine box culverts crossing the highway grade. A precast option was added to all box culverts on subsequent projects because of the speed of installation of precast. IDOT officials, including the chief engineer, felt this would help accelerate construction that had an October 2018 targeted completion date.

Ames Construction won the largest contract of the 37-mile widening with a bid of $62 million, while C.J. Moyna & Sons took the largest number of the remaining contracts and Peterson Contractors of Reinbeck, Iowa, took one. The participating contractors’ preference toward precast concrete structures will be key in completing the projects on an accelerated schedule. Ames and C.J. Moyna offered extensive value engineering proposals to turn cast-in-place to precast whenever possible. This strategy proved valuable by reducing the impact of record rainfall in 2016 that occurred during the prime construction period between April and November. Precast concrete products from Hancock Concrete helped keep all crews on schedule.