Does Public Transit Counteract the Segregation of Carless Households? Measuring Spatial Patterns of Accessibility

Abstract

Although local transit agencies struggle to keep pace with low-density urban development, most people who depend on transit continue to live in concentrated clusters at the core of metropolitan regions, becoming more distant to the variety of places they need to access. Standard transit performance measures fail to help local transportation agencies adapt their services to changes in demographics and urban form. Geographic information systems (GIS) provide a method for measuring transit service at the neighborhood scale while accounting for land-use changes. The first aim was development of a GIS-based accessibility indicator that is straightforward to calculate, easy to interpret, and flexible enough to use for employment and nonwork travel alike. The second objective was to introduce recent advances in spatial statistics to transportation planners to help them quantitatively assess changes in accessibility patterns over time. A case study is examined of accessibility to supermarkets in Syracuse, New York. The analysis finds that over 7,500 households, representing 12 percent of the city’s households, do not have reasonable access to supermarkets. Furthermore, using visual assessment of maps, aspatial database operations, and spatial statistical tests, the study provides statistically significant evidence that poor accessibility is associated both with low-income neighborhoods and with neighborhoods with disproportionately high populations of African Americans.