Abstract
Urban metro tunnel construction frequently suffers from schedule overruns. Although the Umbrella Arch Method (UAM) mitigates ground deformation, its stepwise installation remains highly time-consuming. This study evaluates the Continuous Pipe Arch Method (CPAM) as a time-efficient alternative using scenario-based schedule analysis from Türkiye’s Üsküdar-Ümraniye-Çekmeköy metro project. Construction time uncertainty is modeled via Interval-Valued Fuzzy sets, verified through two concordant computational routes. Results reveal that CPAM reduces per-meter construction time by 32.14% compared to UAM, cutting total project duration from 60.0 to 56.3 months. Combining CPAM with fiber-reinforced shotcrete shortens the timeline to 48.0 months, while expanding the tunnel boring machine (TBM) fleet reduces it further to 38.9 months. Sensitivity analysis confirms robustness, demonstrating CPAM retains its advantage even if drilling times rise by 120%. Seven TBMs represent the optimal fleet size before diminishing returns occur. Ultimately, CPAM shifts the critical path from conventional tunneling to TBM operations, providing evidence-based guidance for urban project selection.