A universal framework for inclusive 15-minute cities (2408.03794v1)

Abstract: Proximity-based cities have attracted much attention in recent years. The 15-minute city, in particular, heralded a new vision for cities where essential services must be easily accessible. Despite its undoubted merit in stimulating discussion on new organisations of cities, the 15-minute city cannot be applicable everywhere, and its very definition raises a few concerns. Here, we tackle the feasibility and practicability of the '15-minute city' model in many cities worldwide. We provide a worldwide quantification of how close cities are to the ideal of the 15-minute city. To this end, we measure the accessibility times to resources and services, and we reveal strong heterogeneity of accessibility within and across cities, with a significant role played by local population densities. We provide an online platform (\href{whatif.sonycsl.it/15mincity}{whatif.sonycsl.it/15mincity}) to access and visualise accessibility scores for virtually all cities worldwide. The heterogeneity of accessibility within cities is one of the sources of inequality. We thus simulate how much a better redistribution of resources and services could heal inequity by keeping the same resources and services or by allowing for virtually infinite resources. We highlight pronounced discrepancies among cities in the minimum number of additional services needed to comply with the 15-minute city concept. We conclude that the proximity-based paradigm must be generalised to work on a wide range of local population densities. Finally, socio-economic and cultural factors should be included to shift from time-based to value-based cities.

• The paper introduces a novel Proximity Time (PT) score to measure the average time required to access essential services by walking or biking.
• It applies an innovative algorithm for reallocating existing points of interest, demonstrating significant improvements in local accessibility and service equity.
• The study emphasizes that tailored urban planning policies are crucial to achieving a 90% 15-minute city status, especially in sprawling urban areas.

Analyzing the Feasibility of the 15-Minute City Model in Global Urban Environments

The concept of a 15-minute city has gained attention as a promising urban planning model aimed at enhancing local accessibility to essential services. This paper provides a rigorous analysis of the feasibility and practicality of implementing the 15-minute city framework in various urban contexts worldwide.

Methodological Approach

The authors present a robust methodological framework to evaluate the accessibility of urban services using open-source data, including OpenStreetMap for points of interest (POIs), WorldPop for population density, and accessibility measurements from the Open Source Routing Machine. The accessibility is quantified using a newly introduced metric, the Proximity Time (PT) score, which measures the average time required to access services within 15 minutes by walking or biking.

The paper further employs an innovative algorithm for optimally reallocating existing POIs across cities. This optimization aims at homogenizing the distribution of services per capita, enhancing equitable access to amenities, and reducing disparities between different urban areas.

Key Findings

The paper reveals significant heterogeneity in accessibility within and across global cities. By evaluating PT scores, the paper identifies stark differences in local accessibility patterns, underlining the core-periphery gradient prevalent in many cities. The computed Gini index further highlights this inequality, pointing towards larger disparities in cities with higher average proximity times.

A simulation of reallocating POIs, using the developed algorithm, shows potential improvements in local accessibility by better distributing existing resources. The paper finds that even without adding new services, a reallocation can substantially improve access in underserved areas. This suggests that policy interventions focusing on decentralizing services could be pivotal in enhancing urban accessibility.

Moreover, the authors explore scenarios requiring additional services to achieve a "90% 15-minute city" status, where 90% of a city’s population can access essential services within 15 minutes. The results show profound differences in the number of POIs required per capita across cities, with denser cities generally needing fewer additional services than sprawling urban areas.

Implications and Discussions

The experimental results and simulations advocate for tailored urban planning policies that consider local population densities and existing service distribution. The paper argues that while the 15-minute city is a viable model for dense urban areas, it is less feasible in cities characterized by low-density suburban sprawl unless significant policy shifts are made.

Furthermore, the findings suggest that while improving spatial distribution of services is critical, integrating socio-economic and cultural considerations is equally essential in shifting towards value-based urban planning models. Such integration would ensure that accessibility enhancements also address broader aspects of urban equity and sustainability.

Future Prospects

This research underscores the necessity for diverse approaches in urban planning to cater to varying urban fabric characteristics. While the paper provides a valuable quantitative framework for assessing and implementing proximity-based cities, future studies should explore integrating other mobility and urban quality-of-life metrics. This comprehensive approach would better account for complex human behaviors and urban dynamics, facilitating more informed and adaptive urban planning strategies.

In conclusion, the paper makes a significant contribution to urban studies by providing empirical evidence on the effectiveness and limitations of the 15-minute city model. It catalyzes a necessary discourse on transforming urban environments into equitable, sustainable, and accessible spaces, setting the stage for continued exploration and policy innovation in designing future cities.