Quantitative Evaluation of the Bim-assisted Construction Detailed Cost Estimates

The increased interest in using Building Information Modeling (BIM) in detailed construction cost estimates calls for methodologies to evaluate the effectiveness of BIM-Assisted Detailed Estimating (BADE) tools in generating detailed construction cost estimates. The focus of this study is on developing a quantified evaluation method to measure the impact of these BADE tools. Further, in order to understand the cognitive details of the estimator, this study also tested and evaluated the impact of the visualization factor and the compound impact of the visualization factor and aggregated calculation factor on the construction cost-estimating process. Two types of BADE tools were tested in this study in order to differentiate the impact of the visualization factor on estimating performance from the compounded impact of both visualization and aggregation functions. A set of test cases with different levels of estimate complexity was designed and tested on entry-level estimators using both traditional manual estimating and BADE approaches. Results obtained from the test cases at several complexity levels helped to reinforce the reliability of the observations and the evaluation. Four parameters were used to evaluate the performance results individually in the first step: generality, flexibility, efficiency, and accuracy. Then a multiattribute utility model, which took into account the four individual parameters, was developed and used to evaluate the overall performance of BIM-assisted estimating versus the performance of the traditional estimating method on quantity takeoffs. The study concluded that the BIM-assisted estimate demonstrated better performance over traditional estimating methods for the entry-level user. Both the visualization and aggregation functions of the BADE tool had significant impact on the performance of the detailed estimate. The study further indicated that the more complex the estimating tasks, the clearer the advantages were of using BADE tools instead of traditional estimating methods. The limitations of the test cases and the test subjects will affect the extrapolation of the conclusions of this research to the broad construction industry. Further study on industry-level cases and subjects is needed to obtain more conclusive findings.