Comparing the performance quality of design-bid-build and design-build delivery methods

摘要

The choice of delivery method is one of the most important decisions that can determine the quality of construction projects. Two basic delivery methods, design-bid-build and design-build, have been compared in terms of project quality; however, an important quality dimension, performance quality, has generally been ignored in previous studies. In this study, the authors used existing economic theories to develop a model to examine the performance quality and project profits of these two delivery methods. The equilibrium points of the model were analyzed with consideration given to influencing factors such as cost coefficient, cooperation efficiency, and coordination cost. Four propositions were made to facilitate the quality-profit comparisons between design-bid-build and design-build. The first proposition showed that to maximize personal profit, the project coordinator should always keep a balance between design quality and construction quality, regardless of the delivery method. The other three propositions indicated that both methods can generate relatively higher levels of performance quality and project profits in an appropriate project environment. Based on these propositions, the authors ranked the performance quality and profits of the two methods within different conditions and used a real project to exhibit the practical value of these findings. Via case study, cooperation efficiency was identified as the most critical factor that determines the selection of delivery method. In addition, three key steps were summarized to facilitate the application of the model developed in this study.