Stay local or go regional? Urban form effects on vehicle use at different spatial scales: A theoretical concept and its application to the San Francisco Bay Area
Abstract: This paper explores the respective roles of local and regional
characteristics of urban form on vehicle travel. We hypothesize that the
effects of urban form on vehicle use at the local and regional levels
are complementary, and we introduce the concept of local and regional
action spaces, which are defined based on the accessibility of
alternative means of transport within an acceptable travel time, to test
this hypothesis. Multilevel and ordered logit models are developed for
the San Francisco Bay Area to estimate the effects of urban form and
socioeconomic characteristics on vehicle kilometers traveled (VKT) and
vehicle trip frequency (for work, shopping, and social/recreational
purposes). We find that the two urban scale characteristics exert
complementary effects on VKT. However, because people in the San
Francisco Bay Area display significantly lower VKT in the local than in
the regional action space, we conclude that regional-scale
inter-ventions would contribute more to the policy objective of VKT
reduction, alt-hough local-scale design policies might also help reach
this policy goal. Intersec-tion density (for the local action space
models) and regional jobs accessibility (for the regional action space
models) demonstrated the strongest and most significant relationships
with VKT. The built environment did not appear to significantly affect
vehicle trip frequency, which is likely due to the uniformly high levels
of vehicle use in both the local and regional action spaces in the
area.
Keywords: Urban form; spatial scales; local; regional; VKT; vehicle trip frequency