, Volume 34, Issue 5, pp 575–588 | Cite as

The impact of urban form on automobile travel: disentangling causation from correlation

  • Colin Vance
  • Ralf Hedel


A longstanding question within the field of transportation demand management is the strength of the relationship between urban form and mobility behavior. Although several studies have identified a strong correlation between these variables, there is as yet scant evidence to support policy interventions that target land use as a means of influencing travel. To the contrary, some of the more recent research has cast skepticism on the proposition that the relationship is causative, recognizing the possibility that households endogenously self-select themselves into communities that support their preferences for particular transportation modes. Focusing on individual automobile travel, the present study seeks to contribute to this line of inquiry by estimating econometric models on a panel of travel-diary data collected in Germany between 1996 and 2003. Specifically, we employ the two-part model (2PM)—a procedure involving probit and OLS estimators—to assess the determinants of the discrete decision to use the car and the continuous decision of distance traveled. Beyond modeling variables that capture the urban form features that are commonly suggested to influence mobility behavior, including mixed use and public transit, this study employs instrumental variables to control for potential endogeneity emerging from the simultaneity of residential and mode choices. Unlike much of the work to date, our results suggest that urban form has a causative impact on car use, a finding that is robust to alternative econometric specifications.


Individual travel behavior Instrumental variables Urban form Two-part model 



We wish to thank Elmar Brockfeld for assistance in creating the GIS measures of road density. We would also like to express our gratitude to Manuel Frondel and to three anonymous reviewers for their comments on an earlier draft.


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Rheinisch-Westfälisches Institut für Wirtschaftsforschung (RWI Essen)EssenGermany
  2. 2.Institute for Transport ResearchGerman Aerospace Center (DLR e.V.)BerlinGermany

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