An assessment framework for 15-minute Cities: Progress worldwide and the impact of urban form

The 15-minute city concept has underscored a commitment to redefine urban life with a more sustainable future. Given the challenges of achieving the 15-minute city and diverse geographic contexts, this study proposes an evaluation framework for assessing the feasibility and progress towards this goal across 35 major cities worldwide in Europe, South America, North America, Asia and Oceania. This framework is a time-sensitive and systematic approach integrating place-based accessibility and population-based measures. Spatial boundaries, facility data, General Transit Feed Specification data and population metrics are used as inputs. There are two key series of indicators: the Basic 15-minute Indicators (1opp15MinC), ensuring at least one opportunity for each essential facility type, and the Optimal 15-minute Indicators (3opp15MinC), providing at least three opportunities for each facility type. The latter emphasises the importance of diversity and choice in service provision. The progress of these 35 cities is then classified into one of three categories: “achieved,” “achievable,” and “unlikely”, using the 50% and 25% thresholds. Our findings indicate that European cities are closest to achieving the basic 15-minute city goals, whereas Australian cities encounter significant challenges. Extending the analysis to a 30-minute timeframe enhances feasibility, particularly in North America, Asia and Australia. Furthermore, we examine the impact of urban form, demonstrating that a decentralised concentration pattern substantially improves access to essential services. This study provides strategic insights for urban planners and policymakers to adapt the 15-minute city concept to various urban contexts and population densities.