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Distribution of green infrastructure along walkable roads
Citation:
Yngve, L. Distribution of green infrastructure along walkable roads. Active Living Research, Clearwater Beach, FL, January 31 - February 03, 2016.
Impact/Purpose:
Demonstrate the distribution of green infrastructure benefits in walkable areas across demographic categories.
Description:
Low-income and minority neighborhoods frequently lack healthful resources to which wealthier communities have access. Though important, the addition of facilities such as recreation centers can be costly and take time to implement. Urban green infrastructure, such as street trees and other green space, can be a low-cost alternative to promote frequency and duration of outdoor physical activity. Street trees and other green space may increase outdoor physical activity levels by providing shade, improving aesthetics, and promoting social engagement. Though street trees and green space provide many benefits and are publicly accessible at all times, these resources are not evenly distributed between neighborhoods. An objective analysis of street tree cover and green space in 6,407 block groups across 10 urban areas was conducted using fine-scale land cover data. Distribution of green infrastructure was then analyzed by minority status, income, car ownership, housing density, and employment density. The objective measure of street tree cover and green space is based on 1-meter resolution land cover data from the U.S. EPA-led EnviroAtlas. Tree cover was analyzed along each side of walkable road centerlines in the areas where sidewalks are estimated to be. Green space was calculated within 25 meters of road centerlines. Percent tree cover and green space per city block were then summarized to census block group (CBG). CBG demographics from the U.S. Census and built environment metrics from EPA's Smart Location Database were categorized into tertiles. In a preliminary analysis, CBG street tree cover, green space, and intersection density were averaged for each population group and compared with linear regression and ANOVA. Average street tree cover and green space were negatively correlated with CBG characteristics: percent living below twice the poverty line, percent other than white non-Hispanic, percent of households without a car, household density, and employment density. The highest tertile of poverty had an average of nearly 10% less street tree cover and 22% less street green space compared to the lowest tertile of poverty. Results from one-way ANOVA indicate that the average street tree cover, green space, and intersection density are significantly different between tertiles of CBG characteristics (p < 0.0001). Preliminary validation of green infrastructure metrics will use physical activity data from the Survey of the Health of Wisconsin. Average street tree cover within 1 kilometer of a participant’s residence will be analyzed by multilevel linear regression, accounting for spatial autocorrelation. By comparing the distribution of street tree cover and street green space across population characteristics and intersection density, the inequitable distribution of health-promoting and publicly accessible green infrastructure can be quantified. In the areas where walkability is theoretically better and the need to walk greater, as indicated by high intersection density and low car ownership, the hospitality of the walking environment is reduced compared to less connected areas. This inequitable distribution of street-side green infrastructure is a concern for environmental justice and equitable access to environments that support and promote physical activity. Understanding the public health benefits and distribution of street-side green infrastructure can help increase its perceived value in our society and to decision-makers. City planners, landscape architects, and tree advocacy groups may use this information in conjunction with local knowledge to support landscape design, tree preservation, and plantings. This publication was supported by Cooperative Agreement Number X3-83555301 between the U.S. Environmental Protection Agency and the Association of Schools and Programs of Public Health. The findings and conclusions of this report do not necessarily represent the official views of EPA or ASPPH.