Comparing Cost, Schedule, and Quality of CM/GC and DBB Project Delivery for Repetitive Commercial Construction

ABSTRACT Design/Bid/Build (DBB) delivery is the traditional approach for establishing the least cost for building projects, but other alternative project delivery methods have become increasingly popular. Although multiple studies have compared delivery methods for vertical construction, there have not been any comprehensive studies quantifying how delivery methods compare specifically for repetitive commercial construction. This research utilized a mixed methods approach to compare the cost, schedule, and quality of Construction Manager/General Contractor (CM/GC) delivered projects with DBB projects for repetitive commercial construction, using 173 facilities built with the same base floorplan. A comprehensive quantitative comparison was conducted, excluding potential confounding variables and including short- and long-term direct and indirect costs, construction time, and quality assessment scores. Contractors and project managers were also surveyed regarding their perceptions of CM/GC process effectiveness in a repetitive construction environment. This research demonstrated that the CM/GC delivery method was more effective for repetitive commercial construction, uniquely quantifying the relative cost, schedule, and quality improvements of CM/GC delivery over DBB projects. Compared to DBB, CM/GC projects produced total construction cost savings of 5.4%, a 20% shorter construction cycle time, consistently higher quality assessment scores, and an overall reduction in repair costs of 34%.