Revisiting the 15-min city through accessibility assessment: A critical systematic review of FMC-based studies

Proximity-centered planning has recently attracted increasing attention. The 15-min city (FMC) and related X-minute frameworks are promoted as strategies for advancing sustainable and equitable urban development. However, limited attention has been paid to how major critiques of the FMC are reflected in empirical studies that apply the framework to accessibility assessment. Rather than evaluating accessibility outcomes, this review examines how accessibility is operationalized and assessed in FMC-based research. To address this gap, this study conducts a systematic and critical review of 149 publications and develops a structured analytical framework across five domains: operationalization and methodological design, social equity and inclusion, implementation and feasibility, governance and participation, and service quality and scale. By organizing the literature around key challenges, the review identifies persistent blind spots in FMC-based accessibility research. The findings indicate that most studies rely on a 15-min threshold, employ quantitative methods, and prioritize residential and leisure amenities, while employment and education remain underexamined. Accessibility is predominantly measured through potential and objective approaches, with limited attention to realized and subjective dimensions. Socio-demographic diversity, multimodal transport integration, stakeholder participation, and service quality are also insufficiently addressed. These findings demonstrate that current applications capture only part of the multidimensional nature of accessibility embedded in the FMC framework. By assessing how recurring critiques are reflected in accessibility assessment practices, this review provides insights for developing more inclusive and context-sensitive accessibility frameworks. Future research should prioritize context-sensitive thresholds, adaptable service classifications, multimodal integration, and participatory approaches to strengthen FMC-based accessibility assessments across diverse contexts.