Is there a link between urban form and automobile use in Germany? Evidence from a selectivity model

Abstract

This study estimates an econometric model of the influence of urban form on non-work automobile travel using a panel of travel-diary data collected in Germany between 1994 and 2003. Two dimensions of car use are considered: the discrete decision to own a car and the continuous decision of distance traveled. Because these decisions are related and, moreover, are likely to be influenced by factors unobservable to the researcher, we apply the Heckman model to control for potential biases emerging from sample selectivity. In addition to including variables that capture the tools commonly advocated by land use planners to influence mobility behavior, an important contribution of this study is to allow the possibility that these variables are endogenous. Unlike much of the work to date, we find that land use variables are a significant determinant of both automobile ownership and use, a finding that holds even after using instrumental variables to capture the effects of urban form.