A review by the Portland Cement Association (PCA) of recent project lettings in Iowa and South Dakota illustrate the dramatic shift in paving material prices. A July letting in Brookings, SD, for the reconstruction of 32nd Avenue was designed as an alternate bid project. Four bids were submitted for concrete and two bids were submitted for asphalt; with two of the concrete bids beating the low asphalt bid. Low prices for the 10,500 square yard project were $870,950 for concrete and $901,253 for asphalt. The concrete bid was also 19 percent under the engineer’s estimate.

Significant Iowa county road lettings show a similar trend, PCA reports. In August 2011, Humboldt County bid 12 miles of alternate design/alternate bid pavement rehabilitation projects. Three different route sections were let as a package due to the proximity of the jobs. The asphalt design included three inches cold-in-place recycling of existing asphalt and a 3-inch asphalt resurfacing. The concrete design specified milling of the existing asphalt to grade and a 4-inch concrete overlay. Six concrete bids were lower than three asphalt bids, with a low concrete bid of $1,792,062. The low asphalt bid was $2,093,006, a 17 percent differential.

More recently, in April 2012, another Iowa county, Delaware County, let six miles of alternate design/alternate bid work on County Road W69. Three concrete bids were lower than the low asphalt bid with a low concrete bid of $1,253,266. The low asphalt bid was  $1,362,951, a 9 percent differential.

When designs are at least reasonably equivalent, concrete bids in many states are now indicative of the shift in pavement surfacing initial cost dynamics.