ABSTRACT
Traffic states are important traffic information for travelers. The existing traffic regulations have a detailed and unique criterion for distinguishing the traffic states. Mostly, the traffic states are defined based on the objectively estimated travel speeds. Yet, it is reported that travelers’ perceptions on travel speeds and traffic states might be different from the objective ones. This paper employs the empirical perception data collected in the city of Beijing to investigate travelers’ perceived travel speeds and traffic states in relation to the objective ones. The effects of travelers’ social characteristics on their perceived speed differences are explored as well. 120 videos, each recording a 5-second traffic condition data, are prepared representing a variety of traffic conditions on different road sections. The objectively estimated travel speed of each video and the associated traffic state based on the traffic regulations were pre-processed. 94 effective participants were asked to judge the traffic states of all 120 videos, and then to report their perceived travel speeds and traffic states for each video. The differences between the perceived and objectively estimated travel speeds and traffic states are analyzed based on the collected data. The results show that users do have significant perceived differences in travel speeds and traffic states. High heterogeneities are found among participants in their perceptions, especially among different gender, age and risk-attitude groups. This study suggests that the existing criterion for distinguishing the traffic states should be adjusted by considering travelers’ perceived differences in travel speeds.
