Utilization of BIM for Construction Cost Estimation of the Girder Bridge Structure in the IKN Project (Karang Joang–KKT Kariangau Segment)

Abstract

The implementation of Building Information Modeling (BIM) is increasingly important for improving the efficiency and accuracy of quantity takeoff and cost estimation in large-scale infrastructure projects. This study evaluates 5D BIM using Allplan Engineering for girder bridge structural work (pile cap, pier, and pierhead) in the IKN Toll Road project, Karang Joang–KKT Kariangau Segment and compares the results with Quantity Surveyor (QS) data and manual recalculation based on Detailed Engineering Design (DED) drawings. Using a comparative quantitative approach, the study developed a 3D model from DED data and performed BIM-based quantity extraction and cost estimation using unit prices from the project Budget Plan (RAB). The results show close agreement across methods, with total differences below 1% for both reinforcement and concrete quantities and costs. Compared with QS, BIM results are 0.17% lower for reinforcement and 0.17% higher for concrete; compared with manual recalculation, differences range from approximately 0.17% to 0.23%. Item-level discrepancies are most evident in Pierhead PH1 (up to 2.72% for concrete) and Pier P1 (up to 3.02% for reinforcement). Overall, 5D BIM in Allplan Engineering provides reliable and traceable outputs for quantity takeoff and cost estimation and supports faster updates during design revisions in national-scale infrastructure projects.