ABSTRACT

Cost estimation accuracy is a critical factor in construction project success as it directly influences project planning effectiveness and cost control performance. This study aims to evaluate the accuracy of Building Information Modeling (BIM)-based quantity and cost estimation and to analyze its implications for cost planning and control in construction projects. A quantitative evaluative approach was applied using a case study of the Dr. Soedono Hospital Parking Building project. Project data were obtained from detailed engineering design documents, bill of quantities, and unit price analysis. Three-dimensional BIM modeling was conducted to generate material quantity take-off for concrete and steel components. Estimation accuracy was assessed using Mean Absolute Percentage Error (MAPE), statistical deviation analysis, and benchmarking against construction cost estimation standards. Cost sensitivity analysis was also performed to evaluate the impact of estimation deviations on total project cost under different material price fluctuation scenarios. The results indicate that BIM-based estimation achieves a very high level of accuracy, with MAPE values approaching 0% for concrete volume and approximately 0.09% for steel quantities, significantly below the acceptable tolerance range of ±5%–±10% in construction cost estimation practice. Sensitivity analysis shows that material price fluctuations have a greater impact on total project cost than quantification errors when BIM-based estimation is applied. These findings demonstrate that BIM enhances cost planning stability, budget transparency, and project cost control effectiveness. This study provides empirical evidence that BIM integration into cost estimation improves accuracy and supports more reliable decision-making in construction project management..