The millennial question: Changes in travel behaviour or changes in survey behaviour?

Abstract

Abstract A great deal has been written in recent years in the travel behaviour research literature about “peak travel” or “peak car”—particularly with respect to the so-called “Millennials”, young adults currently between the ages of 16 and 35. The paper reports and extends the results of longitudinal multivariate regression analysis carried out on the US National Household Travel Survey data from 1995, 2001 and 2009. The results show robust evidence for a decline in auto miles traveled between 2001 and 2009 that cannot be explained by demographic, socio-economic or land use variables or by pure trend effects. The paper then provides a discussion of whether such changes in travel behaviour over time observed from surveys could be due to changes in the survey methods or the way in which different age groups respond to specific types of surveys. There is evidence that young adults have the highest non-response bias (underreporting of trips) for diary-based surveys, but it is not clear if this bias has been growing over time. The paper closes with some suggestions for further data collection.