Value of time by time of day: A stated-preference study

This paper proposes an alternative, dynamic framework for estimating time-varying values of travel time savings and values of schedule delay, in which time-preferences are represented as the time-varying excess-willingness-to-pay (EWPT) to being in the one location, over being elsewhere. It is shown how the conventional linear model, with time-independent values of travel time savings and schedule delay costs, is a special case of our model, and that it is implausible particularly in that it implicitly assumes that the willingness to pay for spending a minute at home instead of being in the vehicle does not vary by time of day, even not for very early departures. The framework is applied to SP data representing the respondents' departure time choices for the morning commute. The results suggest that individuals' time-related shadow prices indeed vary strongly over the morning peak, and values of travel time savings are consequently strongly time-dependent, following plausible and intuitive patterns.