The role of source preference and subjective probability in valuing expected travel time savings

This paper proposes a fully subjective approach to capture the impact of travel time variability on travel decision making that accommodates subjective probabilities and source preference, the latter construct referring to respondent preferences to make judgments on matters that they have reasonable if only vague beliefs about than on matched chance events. The methods of eliciting subjective probabilities and source preference are discussed together with a suggested way forward to introduce, and hence capture parametrically, attitudes towards uncertainty. Using a 2014 survey of commuters in Sydney, we provide examples of modelling source preference and the implications for valuing expected travel time savings. The paper highlights the limitations of stated choice experiments when subjective attribute levels and their occurrence are relevant, suggesting a return to a revised focus on revealed preference data.