Accounting for the uncertainty in an analysis of travel choice experiments using a hybrid choice model

To evaluate the impacts of Transportation Demand Management (TDM) policies on traffic congestion and air pollution, citizens' travel behavior should be investigated accurately. The Choice Experiment (CE) approach could be adopted to investigate the behavior of citizens who may be affected by TDM policies. However, respondents might not be sure about their choices, and this uncertainty can be intensified when CEs are used to assess combinations of TDM policies. The choice uncertainty is a degree (or index) that indicates how uncertain a respondent is about their choice, which could result in inaccuracy in predicting transportation behavior. This study focuses on the mode choice uncertainty when there are three TDM policies, including transit development, cordon, and parking pricing, in an analysis of CEs. In this regard, using a face-to-face survey, the car commuters who traveled to a region in the central part of Tehran, Iran, at peak hours for work purposes were questioned about the reduction of car usage as well as the level of certainty about their decision. Afterward, using a hybrid choice model, respondents' choices and their certainty are addressed by considering panel correlations. According to the results, choice certainty depends on the cordon entrance fee, the number of urban trips per day, the value of the cars owned by the individual's household, age, and gender. The results also indicated that increasing the cordon entrance fee and parking cost reduce the choice certainty.