Performance of Highway Design-Bid-Build and Design-Build Projects by Work Types

Abstract

The design-build (D-B) project delivery method has been used increasingly by state departments of transportation (DOTs) 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, these studies often rely on experts’ judgments or small sample sizes based on data collected from surveys, interviews, or case studies. There are few, if any, empirical studies that have compared D-B-B and D-B highway project performance by work types. This research analyzed 139 pairs of D-B-B and D-B highway projects built by the Florida DOT. The 139 pairs of projects were classified into five categories of work types: (1) new construction; (2) reconstruction; (3) resurfacing, restoration, rehabilitation (3R) projects; (4) intelligent transportation systems (ITS)–related projects; and (5) miscellaneous construction such as sidewalks, bike lanes, or landscaping. The study employed both parametric and nonparametric statistical tests to compare cost growth, schedule growth, and construction intensity metrics across the five project work types. The results show that D-B projects statistically perform better than D-B-B in terms of cost growth and schedule growth for miscellaneous construction and 3R project work types, respectively. Design-build projects also statistically provide a higher construction intensity (more work put in place) than D-B-B for new construction and reconstruction work types. No statistically significant differences between D-B-B and D-B projects were found for other project work types. This study contributes to the construction engineering and management body of knowledge by providing empirical comparisons between D-B-B and D-B project performance on the basis of different types of work. The findings from this paper may provide guidance for state DOTs and practitioners to select D-B project delivery for specific work types and benchmarks D-B against D-B-B.