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The 15-Minute City Quantified Using Mobility Data:

National Investigation and Policy Implications

Principal Investigator(s): Carlo Ratti PhD, Paolo Santi PhD

Project Partners: MIT Senseable City Lab, VW Group of America, City of Boston

Research Project Funding: $144,040

Project Start and End Date: Oct 1st, 2023 – September 30st, 2024

Project Description: In response to social and environmental challenges faced by cities worldwide, policymakers are embracing the "15-minute city" planning model, positing that most human needs should be met within a short walk from home. The 15-minute city's popularity stems from rising congestion, air pollution, climate change, energy consumption, sprawl, and a loss of social interactions, motivating cities to aim for more livable, people-oriented spaces. This popular vision of urban living has taken many names and shapes, such as Paris's 15-Minute City, Portland's Complete 20-Minute, Charlotte's 10-Minute neighborhoods, and Melbourne's 20- Minute neighborhoods. Despite its rising popularity, there is currently no large-scale empirical evidence that can be used to measure exactly how aligned cities and neighborhoods are with the 15-minute vision and assess the distributional implications of advancing that vision. Moreover, there are rising concerns that the decentralization of economic activity and fostering of more inward-focused communities, especially in the context of sprawling and highly segregated North American cities, could exacerbate existing social divides and limit economic efficiency by disrupting the inter-neighborhood flows of people and ideas. In this project, PIs introduce a new measure to quantify local trip behavior using GPS data from 40 million mobile devices across the US. This study defines local usage as the share of trips made within 15 minutes of walking from home. Finally, PIs will test the hypothesis that fomenting 15-minute access and usage could increase the level of segregation in the city.

US DOT Priorities: This project fits well within the US DOT strategic goals of Climate and Sustainability, Equity and Transformation, aiming in a heightened understanding of the benefits of the 15-minute city concept, increased sustainability in urban and transportation planning, and more inclusive and accessible communities across the United States. This project contributes to CCST’s two focus areas including VMT & GHG Reduction via Modal Shift and Changes in Travel Behavior (Focus area 4) and Smart Cities & Innovative Adaptation and Mitigation Technologies (Focus Area 5).

Outputs: The dataset and methodology proposed in this project are novel and will provide the first data-driven evaluation of potential effects of 15-min planning in US cities. In addition to the final report, policy brief, conference presentations and peer-reviewed publications, PIs intend to develop a comprehensive website offering an interactive map showcasing accessibility and local usage data for all neighborhoods and cities across the United States. This website will serve as a valuable resource for public, decision-makers, as well as urban and transportation planners. By providing a visual representation of the alignment of neighborhoods with the principles of the 15-minute city, the website will facilitate a better understanding of the degree to which communities adhere to this concept. This understanding, in turn, will highlight neighborhoods that prioritize environmental sustainability and efficient resource utilization.

Outcomes/Impacts: For the website providing accessibility and local usage maps, the anticipated outcomes include increased awareness and understanding among the public, local decision-makers, and urban and transportation planners regarding the alignment of neighborhoods with the 15-minute city concept. PIs anticipate a substantial number of users interacting with the website in the initial months after launch. As part of research outputs, PIs will develop policy recommendations for fostering 15-minute city principles, and expected outcomes involve the adoption and integration of these recommendations into urban planning discussions and policy debates. The ultimate outcomes are a heightened understanding of the benefits of the 15-minute city concept, increased sustainability in urban planning, and more inclusive and accessible communities across the US. The tangible impacts will be measured by the engagement levels, policy discussions, and potential changes observed as a result of this research.

Research: The findings establish a foundation for future studies on accessible urban living and sustainable design. Policy: The outcomes inform evidence-based policies that prioritize walkability, influencing zoning laws and infrastructure investments. Community: Accessible and local usage maps empower communities to advocate for positive neighborhood changes, fostering engagement. Social Equity: Uncovering potential social segregation effects, the project provides evidence to inform more equitable urban planning decisions.

Perhaps the most enduring benefit of this project will be the widespread adoption of methodology for measuring accessibility, local usage, and experienced segregation. Researchers will likely rely on project’s measures to conduct subsequent studies. For example, current datasets (SafeGraph) do not allow researchers to distinguish the exact mode of travel. An intriguing follow-up study would involve utilizing other data sources that capture detailed travel modes from GPS traces. This approach would enhance our understanding of the individual contributions of different travel modes to the realization of the 15-minute city concept.