Impact of Traffic Images on Route Choice and the Value of Time Estimates in Stated Preference Surveys

A difficult aspect of the use of stated preference (SP) experiments to predict travel behavior is the proper presentation of attributes and characteristics of hypothetical trips to respondents. With an increase in the number of transportation choices, the task of concisely and accurately communicating trip attributes in the SP setting becomes increasingly more important. Recent attempts to introduce innovative strategies into the SP setting have yielded techniques to summarize trip attributes more efficiently for respondents. One technique is to use images of traffic conditions as a supplemental means to summarize average trip speed, travel time reliability, and degree of congestion. However, little research has been performed to test the effects of the use of traffic images on models of route choice built from this kind of SP data. In this research, an SP setting was developed to measure the influence of images of traffic conditions on SP responses. Pictures of traffic conditions that correlated to average trip speed were either shown to or withheld from a survey population from Austin, Texas, depending on random assignment. A panel-effects, mixed, multinomial logit model was built to estimate the respondent's route choice behavior. Overall, the model parameters discovered no evidence to support the assertion that traffic image presentation had a statistically significant effect on route choice with respect to the value of travel time savings or the value of travel time reliability.