Value of travel time and travel time reliability

The value of travel time is an important input to cost-benefit analysis of transport projects. Time gains are often one of the main benefits of transport projects, but they need to be converted from hours and minutes to money units, using a value of travel time. Many countries around the world have official values of travel time (by travel purpose, often also by mode) for this conversion. Only a few countries also include travel time reliability benefits in project appraisal, partly because of lack of values of travel time reliability, but mainly because of a lack of forecasting models that include travel time reliability. This chapter describes methods used for deriving the value of travel time and reliability and briefly discusses how to forecast time and reliability changes. Finally, some selected outcomes and suggestions for future research are presented. In this chapter, we focus on national value of travel time (and reliability) studies, that have been carried out especially in Europe, and that have been feeding into official appraisal guidelines.