Community design and how much we drive

Abstract

The preponderance of evidence suggests that communities with denser and more connected street networks and a higher degree of mixed land uses results in fewer vehicle kilometers traveled (VKT). However, there is less agreement on the size of the effect. Also, there is no clear understanding of the specific aspects of community design-such as street networks and land use mix-that are most important in contributing to lower VKT. One reason why there is some confusion on this point is that past studies have not always made a clear distinction between different street network design characteristics such as density, connectivity, and configuration. In this research, care was taken to control for land use mix while fully characterizing the different features of the street network, including a street pattern classification system that works at the neighborhood level but also focuses on the citywide street network as a separate entity. We employ a spatial kriging analysis of National Household Travel Survey (NHTS) data in combination with a generalized linear regression model in order to examine the extent to which community design, particularly in terms of street network design while controlling land use mix, influences VKT in 24 California cities of populations from 30,000 to just over 100,000. Our results suggest that residents of more compact street network designs tend to drive less. Street connectivity, however, played an adverse role in performance. © 2012 Wesley E. Marshall and Norman W. Garrick.