Quantitative Modeling of Change Order Impacts on Cost and Time Overruns in Indonesian Toll Road Infrastructure Projects

Change Orders (COs) are a major challenge in toll road infrastructure projects, often causing cost and time overruns. This study aims to identify key CO drivers and quantify their impacts on project performance in Indonesian toll road projects. A mixed-methods approach was applied, involving qualitative interviews with 35 experts (project managers, consultants, contractors) and quantitative surveys from 75 respondents covering 20 projects implemented between 2015 and 2023. Data analysis employed descriptive statistics, multiple linear regression, correlation analysis, and hypothesis testing using SPSS. Results show that five significant factors, namely poor planning, technical design changes, discrepancies between plans and site conditions, delays in land acquisition, and inadequate stakeholder coordination, explain 94.5% of CO variation (R² = 0.945). COs accounted for 94.9% of cost overrun variation (R² = 0.949) and 93.6% of time overrun variation (R² = 0.936). Design changes most strongly affected cost overruns (β = 0.419), while land acquisition delays had the greatest effect on time overruns (β = 0.537). COs have interrelated effects on cost and time, requiring integrated management from initiation to closure. The findings provide engineering and policy implications for precise contract documentation, rigorous planning, and proactive risk management to mitigate CO-induced overruns.