Estimating Individual Values of Time in Stated Preference Surveys
2006; Volume: 15; Issue: 1 Linguagem: Inglês
ISSN
1037-5783
Autores Tópico(s)Transportation Planning and Optimization
ResumoThe willingness to pay tolls to obtain reductions in travel time is characterised by the Value of Time (VoT) for each driver. Stated Preference (SP) surveys typically ask respondents to choose between different scenarios, which usually involve a reduction of travel time in conjunction with an increase in toll. This paper describes the methodology and typical results of a survey of drivers, using a variation of the Adaptive Stated Preference survey termed the Semi-Adaptive Boundary-Value SP (SABVSP) survey method. Rather than ask the respondent to evaluate all possible combinations of toll and time saving, the SABVSP method 'learns' from the respondent's early answers, and omits questions which have already been effectively answered by the respondent. This allows the interview to be briefer than is commonly the case, using simple questions that the respondent can understand. The method is innovative in that it produces individual values of Value of Time (VoT) and Toll-Road Constant (TRC) (the amount the driver is prepared to pay to use the toll road at zero time savings, to capture the other benefits of using the tollroad) for each respondent in the sample. Measures of the distributions of these variables can then be derived, rather than assumed, as is usually the case. These show wide variations between respondents, contrary to previous methodologies which work only with mean values of value of time, on the assumption that it is broadly constant across population groups. This finding has significance for toll road operators (e.g. enabling post-stratification of the results to identify market segments with specific values of VoT and TRC). The method has been validated through simulations, with generally good agreement, and has been shown to produce results that are consistent with more conventional SP surveys.
Referência(s)