More than distance: Novel techniques for measuring access to built environment assets

The quality and accessibility of built environment infrastructure, including public schools, parks, grocery stores, and transit, are increasingly recognized as important determinants of health. However, measures of access to such built environment assets often rely on simple counts of resources within a defined geographic boundary or buffer analysis to determine whether a population is or is not within a distance of an asset. These methods do not account for artificial borders, such as neighborhoods, which people travel between, or do not allow for quantification of the volume, quality, or relative proximity of multiple assets.

In many urban areas, sufficient data exist to create spatially refined measures of accessibility that account cumulatively for quality, relative distance, and total volume of assets. For example, retail food establishments within a defined distance of an intersection can each be weighted for their healthfulness and distance from the intersection. The sum of the assets, weighted for healthfulness and distance, can then be normalized to create an access score for each intersection. These intersection access scores can be interpolated onto a continuous surface, describing relative access to different types of resources at any point across the city. The resulting maps provide understandable and compelling portraits of which parts of the city are amenity rich or amenity poor.

This session will discuss the application of this methodology to measuring relative access to schools, parks, transit, and healthy food retail in San Francisco, California. We will provide results from our analyses and interpretation of their implications. We will then review some strengths and limitations of this approach to understanding current environmental deficiencies and utilizing this information for future planning. This session will end with a discussion of how various stakeholders might use the results from these analyses to advance equity in access to high quality environmental resources.