CityTime: A Novel Model to Redefine the 15-Minute City Globally Through Urban Diversity and Proximity

The “15-minute city” (15minC) model has gained global attention as a framework for promoting walkability and sustainable urban mobility. While its adoption has grown, challenges remain in adapting the model to diverse urban contexts worldwide. This paper critically examines the 15minC model, its theoretical limitations, and the need for more context- and user-based approaches to ensure sustainable urban mobility and well-being outcomes across varying morphological, climatic, and cultural settings. The article then introduces the concept of CityTime, which redefines proximity as borderless and adaptable, measuring the minutes needed to walk to customizable ecosystems of urban functions. Using a GIS-based approach, it evaluates the accessibility of points of interest (POIs) to balance their quantitative (proximity) and qualitative (diversity) distribution, proposing new metrics. The approach is tested in Dakar, Rio de Janeiro, and Milan—cities that vary significantly in size, density, and geographic location, representing both the Global North and Global South. Within each city, three distinct areas are selected using a multidimensional clustering method based on POI distributions. These case studies demonstrate the flexibility of CityTime across diverse morphological and socio-economic conditions and its potential to democratize the 15minC ideals, creating more equitable and context-sensitive urban environments globally.