A Robust Method for Evaluating the Potentials of 15-Minute Cities: Implications for Sustainable Urban Futures

The ‘15-minute city’ (15minC) concept, which aspires to bring essential services within reach via a 15-minute walk for all residents, represents a pivotal paradigm shift in sustainable urban development. However, the achievability of this concept for different cities varies considerably across diverse population distributions, urban contexts, and development priorities. In this study, we propose a robust method for evaluating a city's 15minC potential — a city's capability to achieve widespread 15-minute accessibility while maintaining an optimal balance between resource efficiency and resident accessibility. We employ the Location Set Covering Problem optimization model to analyze the resources required to achieve full coverage of 15-minute accessibility and the knee point detection algorithm to assess a city's 15minC potential. Across 23 major Chinese cities, our method exhibits a sharp sensitivity to delineate distinct 15minC potentials. It reveals that cities’ current 15minC development level doesn't align with their inherent potential uniformly. Key determinants include how well current facility locations match population centers and the population density in remote areas. Further, reducing facility constructions by two-thirds has only a marginal impact on accessibility, emphasizing the need for tailored, data-driven planning in effective and sustainable urban development based on the distinct potentials of cities. Our approach prioritizes resource efficiency, minimizing the inefficient use of facilities that serve only a small portion of residents while maximizing the benefits of the 15minC and therefore has significant implications for a sustainable urban future.