An Empirical Comparison of Cost Growth between Highway Design-Bid-Build and Design-Build Projects by Project Size

Abstract

The design-build (D-B) project delivery has been increasingly used in the highway construction industry because of its documented benefits. Many studies have shown the superior performance of D-B projects when compared to traditional design-bid-build (D-B-B) projects. However, there is a lack of an empirical comparison of project performance between D-B and D-B-B projects. This study analyzed cost performance of 2,766 D-B-B and 210 D-B highway projects from five state Departments of Transportation (DOT), including Florida, Indiana, Ohio, Oregon, and Utah DOT. These projects were classified into five categories in cost: $2 million to $10 million; $10 million to $20 million; $20 million to $50 million; $50 million to $100 million; and over $100 million. The result of the statistical analysis shows that D-B projects statistically performed better than D-B-B projects regarding cost growth for project size from $10 million to $20 million, $20 million to $50 million, but not for project size from $50 million to $100 million. Likewise, there is no statistical significance of cost growth between D-B-B and D-B projects for the project size between $2 million and $10 million and the project size over $100 million. The study is, however, limited in sample size to project sizes from $50 million to $100 million and greater than $100 million. Further research should be conducted to validate the findings. State transportation agency officials can use these results to support their decisions when selecting D-B delivery.