This is Cool: New Toolkit has Strategies for Heat Mitigation in Transportation Projects

By: Lydia Kenselaar and Olivia Burry-Trice, Alta

We’ve seen unprecedented heat waves throughout North America this summer, and predictions indicate these weather patterns will increase in severity unless drastic climate mitigation efforts succeed. We’ve also seen what the effects of extreme heat have on active transportation.

A new Toolkit, created in a partnership between Alta, the Southern California Association of Governments (SCAG) and the Cities of Long Beach and Pasadena, provides solutions to the urban heat island effect exacerbated by climate change, which are intrinsically linked to issues of equity and public health. The reference guide allows City decisionmakers and community members to quickly understand the range of cooling strategies that can be integrated into bike, pedestrian, and transit improvements along sidewalks, streets, and alleyways.

“Extreme heat affects people of color and low-income communities more,” said Jennifer Ly, city planner with the City of Long Beach in a recent article from the Long Beach Post. The projects in Long Beach and Pasadena focus on areas with “higher heat vulnerability.”

Similarly, Anita Cerna, senior planner at the City of Pasadena, said, “There is literature out there that suggests, based on what Alta has shared with us, that these harsh conditions do discourage people from walking, especially as temperatures continue to rise,” in a recent Pasadena-Star news article.

Community input was a key driver of this project. Support from Habitat for Humanity LA, the Washington Neighborhood Association, Day One Pasadena, and the Pasadena Complete Streets Coalition were critical to the engagement process. This team helped get people to meetings, encouraged responses to surveys, and connected the dots between heat island effects and allied projects happening elsewhere in the city.

Urban Heat Island Effect

Urban heat islands are areas that experience higher temperatures than nearby less developed areas because they have more paved surfaces and buildings, and less vegetation. They occur when buildings and pavements absorb heat during the day and radiate the heat at night, leading to poor air quality and health problems. The urban heat island effect, made worse by climate change, disproportionately impacts communities of color and low-income communities. For example, according to the EPA, a growing body of research points to “intra-urban” heat islands, or areas within a city that are hotter than others due to the uneven distribution of heat-absorbing buildings and pavements, and cooler spaces with trees and greenery. These differences can result from disparities in the way communities are planned, developed, and maintained.

Similarly, an UC San Diego School of Global Policy and Strategy study released in July showed that low-income neighborhoods with higher Black, Hispanic and Asian populations experience significantly more urban heat than wealthier and predominantly White neighborhoods, with temperatures that can be up to 7 degrees Fahrenheit warmer, compared to the highest-income neighborhoods during the summer months. And in 71% of counties studied, the significant racial urban heat disparities persist even when adjusting for income.

Impacts of urban heat islands include:

• Increased energy consumption as people use air conditioning to keep cool, affecting the energy grid and leading to blackouts and more expensive utility bills
• Compromised comfort and human health, including increased risk of heat-related illnesses, especially for children, elders and those with medical conditions
• Elevated congestion and emissions of air pollutants, like smog, and greenhouse gasses as more people drive to avoid being in the heat
• Impaired water quality; high pavement temperatures warm stormwater and ultimately impact the health of aquatic life
• Environmental impacts like drought and flooding

Urban Cooling strategies to reduce the risk of extreme heat:

The Toolkit offers a number of solutions for communities to combat the effects of extreme heat, including:

• Trees and plantings, which can cool surfaces by as much as 45° F, and improve air and water quality
• Shade structures provide shade at bus stops and in places where there isn’t space for trees
• Cool paving reflects sunlight instead of absorbing it, which can cool surfaces by as much as 20° F
• Walking, biking, and taking transit reduces emissions from driving, improving air quality and reducing heat
• Green Infrastructure reduces ambient and surface temperatures and vehicle speeds while improving wildlife habitat, mental health, and pedestrian and cyclist experiences

Urban cooling design solutions lead to environmental and economic benefits, and reduce the risk of heat-related illness for people who spend time walking, biking, socializing, and waiting for transit outside. Business owners, renters, and homeowners save on air conditioning costs. Communities can enjoy more pleasant public spaces, which encourages more people to walk, bike, and take transit for everyday trips, reducing air pollution associated with driving cars.

When people feel safe and comfortable moving through the community without a car, they become less dependent on cars and can redirect money from car ownership and vehicle maintenance to other goods and services, promoting economic vitality. When fewer people drive, everyone benefits from better air quality and quieter streets, and communities can re-focus resources on other improvements, such as streetscape enhancements.

Regional Cooling Strategies & Neighborhood Case Studies:

The Cooling Long Beach toolkit focuses on the Washington Neighborhood. This neighborhood has limited trees, an impermeable hardscape, and ranks in the 90–95 percentile on CalEnviroScreen. The vulnerability assessment completed for Long Beach’s Climate Action and Adaptation Plan (CAAP) identifies this dense neighborhood as especially vulnerable to the impacts of extreme heat and urban heat island effect.

The Cooling Pasadena Toolkit focuses on two areas: the Lincoln Avenue neighborhood and the Holly/Ramona Street Study area, which encompasses part of Pasadena’s historic Old Town and City Hall. The Lincoln Avenue study area is an ideal location to implement urban greening and cool street strategies; it includes one of Pasadena’s public high schools and is located within Northwest Pasadena with a portion of the corridor ranking in the 90–95 percentile on CalEnviroScreen. The challenges faced by this portion of the City includes above average concentrations of air pollution, hazardous waste and cleanup sites, traffic, and incidences of asthma. Though many efforts have been successful, a lot of progress is still needed with regard to establishing more desirable land uses, quality new development, and a pedestrian-friendly streetscape environment. The Holly/Ramona study area contains numerous features that make it an ideal study location for urban greening and cool streets strategies. It is multimodal, has numerous activity centers that draw a high level of pedestrian traffic, and a range of uses that attract a diverse population.

Both projects were made possible by SCAG’s Sustainable Communities Program, which supports local jurisdictions to address climate change and reduce greenhouse emissions by providing technical assistance to prepare cooling strategies.

Learn more about Alta’s Sustainability Service Area and how we work with communities throughout North America to mitigate the effects of extreme heat and climate change. If you’re interested in strategizing urban heat solutions for your community, contact Lydia Kenselaar.