S. Yamamoto (Ed.): HIMI/HCII 2013, Part II, LNCS 8017, pp. 558–567, 2013. © Springer-Verlag Berlin Heidelberg 2013 Human Behavior of Prioritizing Right-Turning Vehicles and Traffic Flow at Intersections Hironori Suzuki 1,* , Yoshitaka Marumo 2 , Tsuyoshi Katayama 3 , and Yuuki Yazawa 1 1 Nippon Institute of Technology, School of Engineering, Saitama, Japan viola@nit.ac.jp, yazawa.yuuki@nit-trlab.net 2 Nihon University, College of Industrial Technology, Chiba, Japan marumo.yoshitaka@nihon-u.ac.jp 3 Kurume Institute of Technology, School of Engineering, Fukuoka, Japan tkataya@cc.kurume-it.ac.jp Abstract. This study evaluates the effect of prioritizing right-turning vehicles in traffic flow not only at an artificial intersection but also at an existing corridor equipped with several intersections. The traffic simulator used in this study quantifies the effect of prioritizing a right-turning vehicle on traffic efficiency, safety, and the environment of an intersection. The ratio of prioritizing a right- turning vehicle is given as stochastic probability density functions. Numerical analysis showed that low traffic demand and low probability of prioritizing a right-turning vehicle brought significant improvement to traffic efficiency, safe- ty and the environment. The effect was as significant as installing a general right-turn pocket and its special signal phase. It was concluded that humans have potential to improve this efficiency as significant as that of when a right- turn pocket is installed, which is costly and time-consuming. Keywords: Driver Assist, Man-Machine System, Human Interface, Active Safety, Motivation, Right-turn Prioritizing. 1 Introduction Vehicles waiting to complete a right turn often block the vehicles upstream of the intersection and yield a long queue. The traffic congestion due to such blockage is usually avoided by preparing a right-turn pocket (RTP) and/or a special signal phase for the right-turning vehicles as is a conventional method in civil or traffic engineer- ing. Due to the restricted use of land in Japan, many intersections that are prone to such congestion have no available space to prepare a special lane for right-turning vehicles, even at intersections along national highways. The authors have focused on human factor and the motivation of the drivers of the on-coming through traffic to give a “right-of-way” to a right-turning vehicle in order to alleviate traffic congestion around intersections. Although a right-turning vehicle has lower priority when passing through an intersection, according to Japanese traffic * Corresponding author.