Measuring user awareness at signalized intersections

Drivers have limited awareness of changes in trip attributes or the performance of the traffic system. Due to non-utilitarian behavior and perceptual biases a distinctive amount of changes go unnoticed or are valued incorrectly, which makes drivers indifferent to changing traffic conditions to a certain extent. Quantifying user awareness and understanding the probability of behavioral response to changes is valuable input for road operators and traffic engineers designing traffic management measures. This paper presents the results of a field study on user awareness at signalized intersections. The study focused on the ability of drivers to observe and rightly value differences in the timing of traffic lights. Measurements of actual waiting times were compared with perceived waiting times derived from interviews. Results show that drivers’ perception of waiting time was on average fairly accurate, but widely variable, and that waiting times were systematically underestimated. Remarkably, the classification of deviations from the average waiting time showed that the vast majority of the respondents considered their waiting time ‘normal’ or shorter than they were used to. Although in terms of representativeness, field studies are believed to be of great importance to perception studies, the selected approach for this study did not provide the expected data. Therefore it was not possible to provide definite answers related to user awareness at signalized intersections. Advantages, disadvantages and lessons learned are discussed in the paper and have been incorporated in a follow up study as much as possible.