Publication Detail

Understanding the Growth in Non-Work VMT


Research Report

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Suggested Citation:
Handy, Susan L., Andrew DeGarmo, Kelly J. Clifton (2002) Understanding the Growth in Non-Work VMT. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-02-13

If the anecdotal evidence is to be believed, Americans are driving more than ever - and not just for commute trips. Americans don't seem entirely happy about this trend, at least some of this increase in driving appears to be a matter of choice rather than necessity. Either way, the trend has important social, economic, and environmental implications. An understanding of the forces behind this trend might lead to policy responses that reduce how much households drive – or at least how much they have to drive. This report presents a preliminary effort to understand the apparent increase in non-work vehicle-miles-traveled (VMT) at the household level. The first step was to review available data on travel trends to confirm that non-work VMT is in fact increasing. While available data sources provide convincing evidence of this trend, they are far from conclusive. The second step was to explore factors associated with households themselves – the demand side – and with the choices available to households – the supply side. This exploration included an assessment of the trend in each factor and the development of hypotheses about its effect on non-work travel. The final step in this preliminary study was to summarize the findings from existing models of non-work travel behavior on what variables significantly impact non-work travel and in what direction. The report concludes with a discussion of what questions remain and what research approaches may prove fruitful in answering them.