Evaluating the sustainability performance of urban transport systems with a spherical fuzzy hybrid model

Developing sustainable urban transportation systems requires the strategic integration of multiple transport modes while accounting for economic, environmental, social, technical, and operational criteria. However, the complex and uncertain nature of urban mobility, driven by fluctuating travel demand, rapid technological change, and growing environmental concerns, makes the selection of suitable passenger transport modes a challenging decision-making problem. Therefore, this study develops a novel Spherical Fuzzy Multi-Criteria Decision-Making (SF-MCDM) framework to evaluate urban transport alternatives in İstanbul, Türkiye. The model integrates Spherical Fuzzy Delphi (SF-Delphi) with the Content Validity Ratio (CVR) to refine and validate criteria, employs Spherical Fuzzy Stepwise Weight Assessment Ratio Analysis (SF-SWARA) and Spherical Fuzzy Logarithmic Precursor Chain-Driven Objective Weighting (SF-LOPCOW) to synthesize subjective and objective weights, and applies the Spherical Fuzzy Nearest Solution to References (SF-REF) method to robustly rank transport modes while effectively tackling nonlinearities and uncertainty. The results demonstrate that suburban trains provide the highest sustainability performance among the considered alternatives. It is also revealed that by providing more informed and balanced evaluations, the suggested model supports the development of long-term, environmentally responsible, and socially inclusive transportation strategies, a useful tool for urban transport planners and policymakers.