A multi-criteria decision-making framework for strategy selection in hydrogen-based public transportation in metropolitan cities

The transition to hydrogen-based public transportation systems has attracted increasing attention as metropolitan areas seek low-carbon, sustainable mobility solutions. However, large-scale implementation remains constrained by economic, infrastructural, regulatory, and operational barriers. This study proposes an integrated multi-criteria decision-making (MCDM) framework based on Fermatean Fuzzy sets to identify the most appropriate hydrogen transition strategy for Turkish metropolitan municipalities under uncertainty. Barrier weights are determined using Fermatean Fuzzy Analytic Hierarchy Process (FF-AHP), while alternative strategies are evaluated through Fermatean Fuzzy Comprehensive Distance-Based Ranking (FF-COBRA). The findings indicate that economic and financial barriers constitute the most influential barrier group (0.2779), while high capital investment requirements (0.0791) and investment risk and demand uncertainty (0.0718) emerge as the most critical sub-barriers. The results further reveal that the public-private collaboration strategy provides the most effective and scalable transition pathway. Sensitivity analyses conducted under 60 different weighting scenarios confirm the robustness and stability of the proposed framework.