3D Model-Based Quantity Take-Off for Construction Estimates

Reliable estimation of construction project costs requires generation of accurate quantity take-offs. Quantity take-offs are, traditionally, experience-based exercises that are often tedious and time-consuming. Although the BIM platform has been used to improve accuracy and efficiency of quantity take-offs, its widespread use is limited by the intellectual property issues associated with the transfer of complete BIM models or standardized IFC files from owners to contractors. Instead, owners may provide 3D model review files, such as Navisworks, that are capable of integrating 3D models created by various modeling platforms, to contractors. However, this platform does not explicitly provide essential 3D model data, such as component type, shape information, and geometric dimensions, that are essential for generating quantity take-offs. This significantly limits the use of the Navisworks platform, requiring estimators to manually create necessary data for millions of model items. Here, a novel computational approach that addresses these limitations, allowing quantity take-offs to be generated quickly, accurately, and cost-effectively, is proposed. The proposed method was cross-validated by comparing the obtained results to manual measurements. A practical case study based on an industrial construction project in Alberta, Canada, was conducted to test the functionality of the proposed method.