In this paper a stated preference (SP) choice experiment is designed to analyse how the interaction of a latent variable (comfort) with other policy attributes influence mode choice in an urban/interurban context and explores how the different willingness to pay (WTP) measures are affected by the levels considered for this variable. A previous revealed preference (RP) survey of 950 interviews was carried out to obtain information about actual trip behaviour in the two main interurban corridors in Gran Canaria Island and to adapt the SP experiment to each individual's experience. A focus group, recruiting public transport users and car users, helped us to define a final set of five attributes: travel cost, travel time, parking fee, frequency of the service and comfort. A fractional factorial design of 27 scenarios that allow us to measure main effects and two factor interactions among three attributes was divided into three blocks in order to reduce respondent burden. Out of an original sample of 372 individuals, 97 answered the SP survey yielding a total of 871 choice observations. A detailed analysis allowed us to detect captive, lexicographic and inconsistent individuals and to examine how the removal of these observations affected the estimation results. Several linear-in-parameter specifications of multinomial logit models considering only main effects and the interaction of comfort with the rest of the attributes have been estimated including only the SP data set. From these, consistent value of travel time savings (VTTS) and other WTP measures were obtained. The estimation results show that the VTTS decrease from 18.9 euros/h to 9.03 euros/h as comfort is improved from the lowest to the highest level considered in the experiment; it was also found that the WTP for improvements in comfort range from 12.05 euros to 4.44 euros per minute of trip length. For the covering abstract see ITRD E126595.
Abstract