Approach for determining the contract duration of design-build building projects

Unreasonable contract duration is a major cause of contract disputes in construction projects. Establishing a reasonable contract duration is a key factor in minimizing disputes and enhancing the efficiency of construction project management. The design-build (DB) approach has been adopted worldwide. Although the existing approach has provided a robust construction duration estimation model, it is not designed for DB projects. This study aims to fill this gap through intensive literature review, model development, and case validation. This study establishes a robust approach to estimating a reasonable contract duration for DB building projects by using Bromilow’s time-cost model and multiple linear regression. Focusing on social housing construction projects, this study identifies key influencing factors on duration estimation by analyzing 102 completed and ongoing social housing development projects in Taiwan. This study confirmed that the number of above-ground floors, the number of below-ground floors, the adjusted project cost, the impact of uncertainty, and location are the major influencing factors in estimating contract duration. Additionally, this study addresses the uncertainty in contract duration estimation for DB projects, a facet that has not been explored in the existing literature. This study contributes to providing an innovative model for determining contract durations in DB projects.