An empirical investigation of values of travel time savings from stated preference data and revealed preference data

A number of studies have found that the willingness-to-pay (WTP) results estimated from revealed preference (RP) and stated preference (SP) data tend to be different. In this paper, we empirically estimate values of travel time savings from an SP data set and an RP data set and compare the findings within this study and between studies. The evidence shows that the design of a stated choice experiment has a significant impact on the ratio of SP and RP WTP values and reveals that presenting a full distribution of travel time to address random travel time variation in the choice scenarios, along with using a real market reference alternative as a pivot in the SP design, significantly reduces the gap between values of travel time savings estimated from SP data and RP data.