Cost-Benefit Analysis of Continuous Pavement Preservation Design Strategies Versus Reconstruction

Abstract

The Arizona Department of Transportation (ADOT) has traditionally employed continuous pavement preservation as part of an overall design strategy to maintain the highest levels of service for highway users. Concerned about the effects of continual weakening of substructure material layers on preservation treatment cost and performance (i.e., more extensive and more frequent preservation activities), ADOT sponsored a study to determine the cost-effectiveness of the continuous preservation approach as compared with a reconstruction strategy. One goal of the study was to determine the break-even point for the two strategies (i.e., after how many rehabilitation treatments reconstruction becomes as cost-effective as continuous preservation). With inputs such as (a) service life estimates, (b) best estimates of unit costs, (c) work zone-related user costs, and (d) the typical analysis period and discount rate used by ADOT, the total life-cycle costs for four alternative strategies were determined and compared for the 15 commonly occurring pavement scenarios in Arizona. The results of the analysis showed a consistent reduction in total life-cycle costs as the number of rehabilitation treatments performed between original construction and reconstruction increased from none to two. Results also showed that for nine of the 15 scenarios, total life-cycle costs associated with the third reconstruction alternative (two rehabilitations occurring prior to the first reconstruction event) were within 3% of the total life-cycle costs of the continuous preservation strategy. Hence, the break-even point occurs when two to three rehabilitation treatments are performed prior to reconstruction.