Travel time expenditures and travel time budgets - Preliminary findings

There has been discussion now for four decades on the issue of whether or not people around the world have a constant traveltime budget. Most of the research into travel-time budgets has used large aggregate data sets and has shown that average amounts of time spent travelling are on the order of 1 to 1½ hours. There have also been a number of studies that have failed to find evidence of constancy in travel-time budgets. In this paper, the authors report on some preliminary research that uses data from a panel of 50 households that provided GPS data for a period of up to 28 days. In the research to date, the analysis deals only with evidence from one wave of the panel, to determine whether there is evidence over a period of one week of stability in travel-time expenditures. The data set provides very precise times of travel for each person for up to28 consecutive days of travel. The analysis looks at travel time expenditure on a daily basis per person and then aggregates this to a week. The issue of regression to the mean is also considered and reviewed and conclusions are drawn that it is not an issue in this analysis. Evidence is found of some stability in travel time expenditures, especially when data are averaged over a two-week period