Advancing knowledge of design-build and best-value in highway projects

Highway agencies use contracting strategies such as design-bid-build (DBB), low-bid, design-build (DB), and best-value procurement to deliver their projects. Previous studies have shown that the use of DB and best-value helps improve cost project performance. However, some countries remain using DBB with consequent high-cost overruns, and other countries do use DB and best-value but fail in reaching their full potential. Thus, there is a need to revisit current DBB-low bid and DB-best-value practices and provide new knowledge to enhance their performance. To this end, this research aimed to (1) mitigate the main reasons for cost overruns in DBB low bid road projects by exploring measures based on the DB project delivery system; (2) enhance the influence of non-cost factors in DB best-value selection by proposing a systematic approach to write evaluation criteria, and (3) promote a better balance between cost and non-cost factors in DB best-value selection by proposing empirical-based ranges of weights to use in the best-value weighted criteria algorithm. These objectives were achieved by conducting three independent research. The first research provided a mapping of the primary reasons for cost overruns into the phases of design, procurement, and construction by examining 41 interviews using inductive content analysis. It determined what reasons were specific for each of the phases and discussed how the DB delivery system might help minimize these reasons. The second research identified how highway agencies articulated best-value evaluation criteria and proposed a structured approach to enhance current practice on writing these criteria. Through the lens of decision analysis, the researchers conducted a content analysis on 540 criteria included in 98 requests for proposals (RFPs) from 21 states across the United States (US). The analysis found three levels of specificity in writing evaluation criteria. Building upon these levels and on decision analysis theory principles, the research proposed a structured approach to support highway agencies in the process of crafting evaluation criteria. The third research suggested a range of weights to use in best-value procurement, aiming to reach a better balance between cost and non-cost factors in the selection. The research characterized current scoring trends based on a unique data set of 882 non-cost scores and 1,148 cost scores from best-value procurement bidding results. These data were used to simulate the weighted criteria algorithm and explore the balance between cost and non-cost factors. As a result, recommendations on weights were provided to help highway agencies to implement a real best-value selection. This research contributes to the body of knowledge of cost overruns in DBB road projects and best-value procurement for DB highway projects. It is also a unique contribution to the improvement of current state-of-the-practice of agencies managing the design and construction of highway projects.