Anomalies in the value of travel-time changes

Standard practice in econometric estimation of the value of travel-time cha nges divides travellers into market segments and assumes linear utility fun ctions in each category. Here instead we derive a RUM-model from a second-o rder approximation to the utility function. The model is estimated by probi t on data from a recent SP value-of-travel-time study. The influence of soc io-economic variables, trip duration, and so on, on the value of travel-tim e changes is estimated and tested. Our conclusions differ in several ways f rom those of a previous study evaluating the same dataset with the conventi onal method. We find a considerably lower value of travel-time savings and signs of a cognitive threshold; respondents decline travel time savings sma ller than 10-15 minutes irrespectively of the bid price. The non-linear app roach also provides a convenient means for benefits transfer, that is, to c alculate the mean value of time savings for a specific road project, depend ing on how it will be used, and by whom.