A Review of Evidence on the Value of Travel Time in Great Britain

Abstract

The purpose of this research was to review the large number of empirical studies which have been conducted in Britain since 1980 which provide value of time estimates. The wealth of evidence that exists is useful in interpreting the results of current studies and in evaluating current practice, both in estimation and application, whilst it can be expected to identify areas for further research. We have reviewed 105 studies based on disaggregate methods and either Revealed or Stated Preference data. These studies have yielded 444 value of time estimates, disaggregated by at most purpose and mode, which represent a wide range of circumstances. The main aspect of the research has been the development of a regression model to explain variations in the value of time across studies as a function of relevant variables. The latter include GDP, distance, journey purpose, type of data and choice context, method of SP presentation and mode used and valued. This model allows value of time estimates to be obtained for situations which can be covered by the variables it contains. The study has also conducted a detailed review based on within-study variation in the value of time. A number of interesting findings have emerged, including the consistency between current Department of Transport recommendations and previous evidence and similarity between the reviewed studies and the results of the Department of Transport's recently completed value of time study. The value of time is found to vary according to mode, purpose and distance whilst there is encouraging evidence with regard to the correspondence of values of time derived from Revealed and Stated Preference models. A number of recommendations are made on the basis of this review. These include the extension of this type of review to cover types of travel time other than in-vehicle time, and further research relating to the impact of group travel, the numeraire and the size and sign of travel time variations on the estimated value of time