Comparative Analysis on Design Error Risks in Design- Bid-Build and Design-Build Construction Approaches

Abstract

This study was conducted to compare design errors risk in Design-Bid- Build (DBB) (traditional) and Design-Build (DB) methods in building projects. Several construction projects under both DB and DBB method were reviewed. On most of construction projects under DB method, it was found that there were over supply of floor area due to different reasons. Also, it was found that, clients’ requirements were changed during project execution, which resulted into change on schedule, contract value and project quality. It was also revealed that in most cases, designs were in accordance with the clients’ requirements as submitted earlier but during construction clients requested to add some items, which resulted in change of both contract sum and period. For projects under DBB method, the results showed that during project enactment, projects experienced design errors in different ways such as change in specifications, slow decision making, unforeseen conditions and change in clients’ requirements as the aspect of design errors. Approvals of changed materials and additional works were delayed in some occasions; thus, leading to contractors to slow down the construction. It was also further found that the variation in final cost, time and project quality of building construction projects due to design error aspect is more likely to occur when using DB as a delivery method than DBB. The study suggests knowledge sharing, visitation to site before designing and proper planning for design error reduction.