Assessing the Potential of Shaded Routing for Active Mobility in Urban Street Networks

Core Concepts

Shade from buildings can provide cooling and protection for pedestrians, but the extent of this potential benefit is unknown. This study explores the potential for shaded walking using building footprints and street networks from both synthetic and real cities.

Abstract

The authors introduce a route choice model with a sun avoidance parameter α and define the CoolWalkability metric to measure opportunities for walking in shade. They derive analytically that on a regular grid with constant building heights, CoolWalkability is independent of α, 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.
The authors 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. The 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.

Stats

"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."
"We derive analytically that on a regular grid with constant building heights, CoolWalkability is independent of α, and that the grid provides no CoolWalkability benefit for shade-seeking individuals compared to the shortest path."
"Variations in street geometry and building heights create such benefits."
"The potential for shaded routing differs between grid-like and irregular street networks, forms local clusters, and is sensitive to the mapped network geometry."

Quotes

"Shade provision is frequently overlooked in urban planning and climate-change mitigation strategies, despite being one of the most efficient and cost-effective ways to reduce heat-related health risks outdoors."
"Improving shade provision has the dual benefit of minimizing the harmful impacts of a changing climate while stimulating sustainable modes of mobility that do not contribute to further climate change."

Key Insights Distilled From

CoolWalks: Assessing the potential of shaded routing for active mobility in urban street networks

by Henr... at arxiv.org 05-03-2024

https://arxiv.org/pdf/2405.01225.pdf

Deeper Inquiries

How can the insights from this study be used to inform urban planning policies and interventions to improve shade provision and promote active mobility in cities?

The insights from this study can be instrumental in shaping urban planning policies and interventions aimed at enhancing shade provision and promoting active mobility in cities. Here are some ways in which these insights can be applied:

Optimal Shade Provision: By understanding the relationship between street network geometry, building heights, and shaded routing, urban planners can strategically design urban spaces to maximize shade provision. This can involve incorporating taller buildings strategically to create more shaded areas along pedestrian and cycling routes.

CoolWalkability Metrics: The development of metrics like CoolWalkability can provide a quantitative measure of the potential for shaded routing in urban areas. Planners can use these metrics to identify areas with low CoolWalkability and prioritize interventions to improve shade provision in those locations.

Diurnal Profiles: The diurnal CoolWalkability profiles can offer insights into how shade availability changes throughout the day. Urban planners can use this information to design interventions that optimize shade provision during peak sun exposure times, such as aligning street layouts to minimize direct sunlight exposure.

Spatial Clustering: The identification of spatial clusters with varying CoolWalkability profiles can help planners target specific areas for interventions. By focusing on areas with lower CoolWalkability, interventions like planting trees, installing canopies, or redesigning street layouts can be implemented to enhance shade provision.

Equity Considerations: Planners can use these insights to ensure that shade provision and active mobility infrastructure improvements are equitable and benefit all community members. By targeting areas with high heat exposure and low shade provision, interventions can address environmental justice concerns.

What are the potential limitations or drawbacks of relying solely on building-provided shade as an adaptation strategy, and how can these be addressed?

While building-provided shade can be a valuable adaptation strategy for mitigating heat exposure in cities, there are some limitations and drawbacks to consider:

Uneven Distribution: Building-provided shade may not be evenly distributed throughout a city, leading to disparities in shade availability across different neighborhoods. This can exacerbate existing inequalities in heat exposure and access to comfortable outdoor spaces.

Seasonal Variability: The effectiveness of building-provided shade can vary seasonally, with less shade available during winter months when the sun's angle is lower. Relying solely on building shade may not provide adequate protection during all seasons.

Maintenance and Sustainability: Building-provided shade requires ongoing maintenance, such as pruning trees or cleaning canopies, to remain effective. Without proper upkeep, the shade may deteriorate over time, reducing its cooling benefits.

Limited Reach: Building-provided shade may not extend to all areas of a city, particularly in dense urban environments with limited green space. This can leave certain areas exposed to high temperatures and limit the effectiveness of shade as an adaptation strategy.

To address these limitations, urban planners can consider a holistic approach to shade provision that includes a mix of strategies such as planting trees, installing green infrastructure, creating shaded public spaces, and incorporating shade structures in urban design plans. By diversifying shade sources and considering the seasonal variability of shade, cities can create more resilient and equitable shade provision strategies.

How might the findings from this study on the relationship between street network geometry, building heights, and shaded routing apply to other modes of transportation beyond walking, such as cycling or public transit?

The findings from this study on shaded routing and street network geometry can have implications for other modes of transportation beyond walking, including cycling and public transit:

Cycling Infrastructure: Similar to walking, cyclists also benefit from shaded routes that provide relief from direct sunlight and heat exposure. By applying the insights on building heights and street geometry, urban planners can design cycling infrastructure that maximizes shade provision, improving the comfort and safety of cyclists.

Public Transit: Shade provision can enhance the experience of public transit users waiting at bus stops or train stations. Understanding how building heights and street layouts impact shade availability can inform the design of transit hubs and shelters to optimize shade coverage for passengers.

Multi-Modal Connectivity: Considering shade provision in the design of transportation networks can improve the overall multi-modal connectivity of a city. By creating shaded pathways that cater to pedestrians, cyclists, and public transit users, cities can encourage sustainable and active modes of transportation while enhancing the overall urban environment.

By applying the principles of shaded routing and CoolWalkability metrics to cycling and public transit infrastructure planning, cities can create more comfortable, accessible, and sustainable transportation networks for all residents.