Spatiotemporal Dimensions of Modal Accessibility Disparity in Boston and San Francisco

Abstract

The disparity of accessibility between cars and public transit provides important information about the degree of auto orientation in urban spatial structure. Using spatial data from 1990 and 2000 and a geographical information system, the present study examined the degrees and spatial variations of accessibility disparity between commuting by car and public transit as well as the temporal changes in this disparity in the metropolitan areas of Boston and San Francisco. In both metropolitan areas there was a considerable disparity in job accessibility in a comparison between users of cars and public transit, which turned out to differ substantially by location. Between 1990 and 2000 regional levels of this accessibility disparity lessened in the two metropolitan areas, but the temporal changes in the accessibility disparity varied considerably among different locations within the metropolitan areas. The accessibility disparity decreased in the majority of central areas and in a number of suburban zones near rail stations, whereas the accessibility disparity increased in a number of suburban zones near major highways. Improving accessibility for public transit, relative to that for cars, should be a key strategy for redressing auto-orientation urban spatial structure, an important objective of sustainable development.