The Contribution of Work, Leisure and Travel to the Subjective Value of Travel Time Savings
JARA-DIAZ S and GUEVARA C A, Universidad de Chile, Chile
The subjective value of travel time (SVTT) calculated from discrete travel choice models as the trade off between cost and time in modal utility, represents the willingness to pay to diminish travel time (either in vehicle, waiting or walking). This SVTT
The subjective value of travel time (SVTT) calculated from discrete travel choice models as the trade off between cost and time in modal utility, represents the willingness to pay to diminish travel time (either in vehicle, waiting or walking). This SVTT can be shown to reflect the sum of at least two effects; first, the willingness to substitute travel time for other more pleasurable or useful activities and, second, the direct perception of the reduction of travel time itself. Regarding the first effect, one such substitute activity could be paid work, in which case the SVTT will also include the additional money earned (or its equivalent goods consumption). Hundreds of travel choice models have been estimated throughout the world from which values of time have been calculated. Its components, however, have never been examined quantitatively. In this paper we formulate a framework that permits the estimation of these components, which is then applied experimentally using reliable data from Santiago, Chile.
The paper is organised as follows. First, we develop a microeconomic model of time assignment to activities that follows DeSerpa (1972), from which a discrete travel choice model can be derived. An association is then established between the SVTT and the value of leisure (or resource value of time), the wage rate, the marginal value of work, and the marginal value of travel time. Using a Cobb- Douglas form for utility, in section three we show that the mode choice model can be coupled with a model that links activity times with the wage rate, such that the components of the SVTT can be actually calculated. To apply this approach, data on activities (time at work, at home and travelling) and on mode choice from a sample of users in Santiago (two income strata) is described in section four along with models and results. A synthesis and conclusions are offered in the final section. Beyond this novel methodological approach, the main numerical results are that all individuals dislike both work and travel, and that the resource value of time contributes between 11% and 14% to the SVTT.
Association for European Transport