Car-Following Criteria at a Signalized Intersection in Beijing

It is commonly agreed upon that car-following only takes place when the separation between two vehicles is within some threshold value. This threshold has been studied but most of the work focuses on highway or motorway traffic and does not consider car-following in intersection areas. This paper studies the car-following threshold criteria in a signalized intersection area. The close-range photogrammetry system is built to collect and analyze traffic data at a signalized intersection in Beijing. The speed difference analysis method and K means the cluster method is employed to distinguish the car-following status and to obtain the critical headway and spacing for car-following. The results show that the critical headway of car-following at the signalized intersection is three seconds and the critical spacing is 20 meters. The main contributions of the paper are the close-range photogrammetry system developed for data collection, and the speed difference analysis or judging the car-following status at a signalized intersection.