OICC Press Iranian Journal of Earth Sciences 2228-785X 18 2 2026 06 30 Uncertainty Modeling for Estimating the Construction Scheduling of Mechanized Tunneling 10.57647/j.ijes.2025.16985 EN Javad Ziaei Faculty of Mining, Petroleum and Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran Mohammad Ataei Faculty of Mining, Petroleum and Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran Reza Kakaie Faculty of Mining, Petroleum and Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran Journal Article 2026 06 30 Accurately estimating the construction duration of long tunnels during the feasibility and initiation phases is crucial. Traditional estimation methods often lack precision. This paper introduces novel simulation-based approaches to provide more accurate forecasts of tunnel construction time, thereby minimizing the gap between planned and actual durations. This innovation involves identifying risks influencing tunnel construction, categorized as known and unknown, by experts. These risks are then ranked and weighted using the Fuzzy Analytic Hierarchy Process (FAHP). Significant risks are simulated as inputs in MATLAB software using the Monte Carlo method. The results indicate a six-year construction duration for the identified risks. The probability of adhering to the schedule is 100% in the first year, decreasing to 89% in the second year, 92% in the third year, and 90% in the fourth, fifth, and sixth years. For unknown risks, the probability is 90% in the first year, 93% in the second year, 90% in the fourth year, and 92% in the fifth and sixth years. Based on these findings, contingency and management reserves should be added to the forecasted schedule in accordance with the PMBOK standard to minimize discrepancies between planned and actual schedules.