Two dimensions of car use are considered: the discrete decision to own a car and the continuous decision of distance travelled. Because these decisions are likely to be influenced by factors unobservable to the researcher, the research applies censored regression models to
evaluate the role of biases emerging from sample selectivity.

Unlike much of the literature, the researchers find that urban form variables are a significant determinant of both automobile ownership and use, a finding that holds even after using instrumental variables to control for endogeneity.

The hypothesis of a link between urban form and automobile dependency has far reaching implications for transport and land use policy, as its verification would avail a broad palette of options to encourage alternative modes of travel. Establishing such a link empirically, however, has proved a vexing endeavour.

The study seeks to further contribute to this line of inquiry by estimating econometric models of car use on a panel of travel-diary data collected in Germany between 1996 and 2003.

Unlike much of the work to date, the researchers find that the urban form variables are a significant determinant of automobile ownership and distance driven, a finding that holds even after controlling for the possibility that these variables are jointly determined by other factors influencing residential choice decisions.

RWI Essen
Colin Vance, tel. +49 2018149237

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01/09/2006

Colin Vance and Ralf Hedel

research

Urban Policy > Urban environment

Land use