| The design-build (DB) system has been demonstrated as an effective delivery method and has gained its popularity worldwide. Many academic researchers have conducted studies on the selection of DB delivery method; however, there are few studies on the selection of DB operational variations, which poses challenges to many clients. The selection of DB operational variation is a multi-criteria decision making process, which is often characterized by subjectivity and uncertainty. In order to resolve this deficiency, the current investigation aimed to establish a fuzzy multi-criteria decision-making (FMCDM) model for selecting the most suitable DB operational variation.;Since the classification of DB operational variation remains controversial in the DB field, a comprehensive classification framework was first constructed through a comprehensive literature review and content analysis. Five operational variations of DB system including develop and construct, novation design-build, enhanced design-build, traditional design-build and turnkey were proposed and served as the basic alternative options in the selection of DB operational variations. A three-round Delphi questionnaire survey was then conducted to identify the selection criteria and their relative importance. Seven top selection criteria and their importance weightings were finally identified, which include, namely, (1) availability of competent design-builders, with the weighting of 0.178; (2) owner's experience, with the weighting of 0.156; (3) project complexity, with the weighting of 0.147; (4) owner's control of project, with the weighting of 0.137; (5) early commencement & short duration, with the weighting of 0.132; (6) reduced responsibility or involvement, with the weighting of 0.127; and (7) clear end user's requirements, with the weighting of 0.122. A fuzzy set theory approach, namely the modified horizontal approach with the bisector error method, was applied to establish the fuzzy membership functions, which enables clients to calculate the performance of each DB operational variation against the selection criteria. The FMCDM was finally developed using the weighted mean method to aggregate the overall performance of DB operational variations with regard to the selection criteria. The selection model will not only offer a better understanding of different DB options but also can be used as a guideline for the DB delivery practice. |
