Predicting performance of design-bid-build projects

Design-bid-build (DBB) is the most common delivery method for public and private construction projects in Spain, and is also widely used in the United States (U.S.). While the execution of DBB projects in Spain and the U.S. is similar in many ways, owners in Spain approach the procurement of the general contractor and subcontractors differently. There is a greater emphasis on selecting firms that provide the “best value” of cost, quality and expertise. Comparatively, U.S. owners leading a DBB delivery are more concerned with achieving the lowest first cost. Using data from 67 completed DBB projects in Spain and the U.S., a best subsets regression analysis was performed to develop five models, each predicting a key performance outcome of DBB projects: cost growth, schedule growth, unit cost, delivery speed and intensity. These models separated the effects of the country of origin from other explanatory variables that effect performance. These other explanatory variables include differences in the procurement process, payment terms, the initial unit cost, size of the project, and measures of the project team’s integration and cohesion. The findings of this study show that, while owners in Spain opt for a more robust procurement process, DBB projects in the U.S. have comparable unit cost and are delivered faster and with a greater intensity when all other variables are held constant. This suggests that factors unique to the country of origin, not directly related to the execution of DBB projects, have a distinct effect on their performance.