Timing of Cost Certainty in Highway Construction Project Delivery: Perceptions versus Empirical Results

Abstract

The early timing of cost certainty during highway project delivery is a primary reason for using alternative contracting methods, but the relative performance of these delivery methods has not been quantified by previous researchers. This research addresses the gap in knowledge by quantitatively showing how the traditional design-bid-build delivery method and the alternative contracting methods of construction manager/general contractor (CM/GC) and design-build (D-B) compare in the timing of cost certainty on U.S. highway construction projects. A novel comparison of the performance of CM/GC versus D-B projects procured by best value is performed. The results reveal a difference between the perceptions of agency decision makers and empirical project performance. By comparing empirical project data with findings aggregated from experts in a Delphi study and with a review of the limited relevant literature, this paper highlights contradictory findings and inconsistencies in the relative performance among the different sources of information. For the alternative contracting methods, the empirical project results show earlier timing for cost certainty than perceived by agency experts. Results reveal that agency personnel underestimate the potential time savings of CM/GC because they believe that D-B is faster to the point of cost certainty. However, empirical data show that CM/GC is substantially faster. The authors emphasize the need for further research to clarify the contradictions and inconsistencies in order to produce reliable, validated results that can provide useful recommendations for application in highway construction project delivery.