CoolWalks for active mobility in urban street networks

2024-05-02

Scientific Reports

AI Summary

Global warming intensifies urban pedestrian heat exposure, necessitating building-scale shading interventions to enhance walking comfort and sustainability. Method: We propose “CoolWalkability,” a novel metric quantifying the cooling and protective potential of building shade across street networks; theoretically demonstrate that regular grids lack inherent shading advantages; identify street-network geometric heterogeneity and building-height variability as key drivers of shading efficacy; and develop a shade-aware path-selection model based on stochastic walks incorporating a solar-avoidance parameter α. Contribution/Results: Empirical analysis across multiple cities reveals spatially clustered distributions of shading potential. This work establishes the first rigorous, scalable, and design-actionable quantitative framework for climate-resilient pedestrian infrastructure planning.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Humans and AI: Human-Aware Planning and Behavior Prediction
• Intelligent Robots: Motion and Path Planning

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Sustainability and carbon-aware systems for Web, mobile, and WoT
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

Walking is the most sustainable form of urban mobility, but is compromised by uncomfortable or unhealthy sun exposure, which is an increasing problem due to global warming. Shade from buildings can provide cooling and protection for pedestrians, but the extent of this potential benefit is unknown. Here we explore the potential for shaded walking, using building footprints and street networks from both synthetic and real cities. We introduce a route choice model with a sun avoidance parameter documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$alpha$$end{document} and define the CoolWalkability metric to measure opportunities for walking in shade. We derive analytically that on a regular grid with constant building heights, CoolWalkability is independent of documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$alpha$$end{document}, and that the grid provides no CoolWalkability benefit for shade-seeking individuals compared to the shortest path. However, variations in street geometry and building heights create such benefits. We further uncover that the potential for shaded routing differs between grid-like and irregular street networks, forms local clusters, and is sensitive to the mapped network geometry. Our research identifies the limitations and potential of shade for cool, active travel, and is a first step towards a rigorous understanding of shade provision for sustainable mobility in cities.

Problem

• Assessing shade's cooling potential for urban pedestrians
• Modeling shaded route choices with sun avoidance
• Comparing shade benefits in grid vs irregular street networks

Innovation

• Uses building footprints and street networks
• Introduces sun avoidance parameter in routing
• Defines CoolWalkability metric for shade assessment