Measuring Accessibility For Pedestrians, Bicyclists, And Transit Riders To Grocery Stores In The Excelsior/Outer Mission Neighborhoods Of San Francisco

Abstract

Grocery stores are an important amenity in neighborhoods and access to grocery stores is important for health and well-being. While grocery store accessibility is a popular topic of research, studies measuring access for pedestrians, bicyclists, and transit riders are extremely rare. When a new store opened in the Excelsior/Outer Mission districts of San Francisco on a street lacking basic infrastructure for pedestrians, bicyclists, and transit riders, the importance of this study became apparent. The Excelsior/Outer Mission neighborhood has a shocking number of collisions (over 1,100 between 2015 and 2019), elevated levels of walking, biking, and transit ridership, and minimal safe infrastructure for these modes compared to other residential areas in San Francisco. To account for the effects of these conditions on accessibility, a rating system to measure infrastructure for users was used in addition to the more traditional gravity model. Combining results into a composite accessibility score highlights how using only a gravity model to measure accessibility may conceal some of the nuances of accessibility as perceived by pedestrians, bicyclists, and transit riders. While it appears from gravity indices that stores in the Excelsior/Outer Mission are only slightly less accessible, the sensitivity analysis shows that infrastructure can have a large effect on overall accessibility. Specifically in the Excelsior/Outer Mission neighborhood, with its rather low infrastructure scores, the higher the weight attributed to the importance of infrastructure the lower is composite accessibility. Rather than measuring accessibility using only travel time via a gravity model or other spatial model, this study shows the importance of combining physical proximity measurements with infrastructure information to provide a more complete picture. This is particularly important for those walking, biking, or riding transit where safety is an important consideration. This study provides one such way to include the unique considerations of pedestrians, bicyclists, and transit riders by including an infrastructure scoring system. Not only does this highlight the importance of including infrastructure measures, but it provides a framework for future infrastructure improvements around stores