A small but growing body of evidence that questions the traditional view that travel is a derived demand is beginning to be assembled. Rather than assuming that all the positive components of a trip are contained in the activity at the destination, while the trip itself contains only disutility, a view is emerging that perhaps some people actually enjoy the travel component of the trip or at least are not willing to pay for reductions in the duration of the trip. One small addition to the patchwork of studies that are starting to form a basis for challenging the conventional assumption about positive value of time (VOT) is provided. By using the results obtained from a study of VOT in Singapore that used an adaptive stated preference survey technique, it was found that 23% of public mode users in that study had zero VOT, whereas 0% of private mode users in Singapore had zero VOT. Analysis of the characteristics of those with zero VOT shows either that they had lower incomes or that they had a greater degree of flexibility in their use of time. Some recent studies that have considered changes in VOT over time, in which there are indications that the marginal utility of time has been decreasing over time (because of increased free time, the increased utility of time spent traveling because of improved telecommunications, and a range of other factors), are also described. The implications of the findings are described in terms of the modeling of travel behavior and the evaluation of transport proposals.
Samenvatting