The benefits of transport projects are mainly derived from individual travel time savings. However, the value or values that should be attached to those savings for the purpose of social projects appraisal remains a question with no clear answer. Many national studies have been conducted throughout the world in order to calculate individual subjective values of time for a variety of difference to travellers facing different circumstances. These values have been used either as direct prices of time or as inputs to calculate one or more synthetic values for transport planning and appraisal. In this paper the social valuation of travel time savings in general is discussed, assuming that all required travel demand models (involving required travel demand models (involving implicit subjective values of time) are available to the analyst. It is shown that social values of time welfare consistent with welfare theory involve users' perception of time, the valuation of money of those whose funds are used, and political (value) judgments. Both a single social value of time and individual specific values are shown to be particular cases of a general analytical expression that is derived from this paper.
Abstract