Design-Bid-Build (DBB) vs. Design-Build (DB) in the U.S. public transportation projects: The choice and consequences

Should public-sector owners use Design-Build or Design-Bid-Build to deliver projects? To seek answers to this question, this study tackles the following questions related to fundamental decisions in the procurement process: 1) For which project owners are likely to employ one delivery method or the other? 2) To which contractor owners tend to award Design-Build projects? and 3) How different are the consequences of the decisions between the two methods in terms of cost and schedule? Economic theories of contract selection suggest that Design-Build would fit better with large, environmentally uncertain, and technologically challenging projects, thereby, requiring better-qualified contractors. However, analyses of comprehensive data on public transportation projects in Florida reveal some misfits between theories and the reality. Regardless, Design-Build seems advantageous to schedule control, while cost advantages of one method over the other is still inconclusive. This study concludes with some implications of these findings for efficient deliveries of public infrastructure projects.