Design-Build Performance over the Years: An Exploration into Colorado’s Experience

Design-build (D-B) has been a Federal Highway Administration authorized delivery method since the special experimental projects-14 pilot program in 1990. Today D-B is used so frequently amongst select states that it is hardly an “alternative” delivery method. A large amount of literature has been dedicated to studying D-B’s cost, schedule, productivity, and quality performance. This accumulation of literature has given researchers and practitioners an understanding of D-B performance in comparison to design-bid-build (D-B-B). Missing from these studies is the D-B’s performance over time. Existing literature datasets infrequently span longer than 5 years, and none discusses D-B’s performance over time. This research fills this gap by investigating if Colorado DOT (CDOT) is increasing in their D-B performance metrics over time, as they have matured in their D-B use. CDOT was chosen for study as it is one of the more innovative states in its use of D-B, having recently developed a project delivery selection matrix that ensures D-B is considered for most potential projects. However, our findings indicate that CDOT used D-B for only 21 of the 755 (or 3%) highway construction projects analyzed between 2008 and 2016. Potentially due to the small dataset, no statistical difference of cost growth was observed between D-B-B and D-B within these CDOT projects. From existing literature, this could be caused by D-B being more often chosen for innovation, schedule acceleration, and risk transfer on complex projects versus cost savings. Finally, D-B showed no trend of improvement/decline of cost growth over the years, although D-B-B did show non-statistically significant trend data of cost growth improvement throughout 2008–2016. This study adds to the current body of knowledge and provides practitioners a better understanding of the characteristics of the D-B market.