Evaluating Awareness and Perception of Waiting Time at Signalized Intersections: Field Study

Transportation researchers increasingly acknowledge that the perceived level of service of the traffic system reflects drivers' experience much better than does the observed level of service. Especially when traffic management measures change the level of service, understanding how this change is perceived by drivers is vital to the prediction of whether drivers will adapt their behavior. Psychological and behavioral literature indicates that user awareness of changes is usually limited and that many changes go unnoticed; however, empirical evidence in a transportation context is scarce. This study focused on stopped delay at signalized intersections and addressed the accuracy of drivers' perception of absolute waiting time at signalized intersections and drivers' level of awareness of differences in waiting time. Data were collected by means of interviews and manual waiting time measurements. The results showed that on average respondents could estimate fairly accurately the size and direction of the absolute waiting time, but had little sense of relative differences in waiting time. In addition, small waiting times were found to be overestimated, but waiting times greater than 55 s were underestimated, and the perception error never exceeded the maximum actual waiting time. An unpredicted finding was that the vast majority of the respondents stated that their waiting time was shorter than expected, even in the case of long waiting times. Finally, the perception error was found to double when drivers thought that their expectations were violated.