Left-Turn Gap Acceptance Behavior of Tee Type of Unsignalized Intersection

Gap acceptance is the main parameters of intersection capacity and safety research. Although the domestic and foreign scholars and researchers have studied the critical gap deep in the capacity researches, very few paper has been discussed the process of gap acceptance from the view of traffic safety behaviors. The objective of this paper is to analyze the safety behavior of gap acceptance, to examine the relationship between gap acceptance behavior and waiting time, and to make suggestions of safety traffic control design for unsignalized intersections. The authors observed 1216 left-turn gap-acceptance behavior samples from 11 tee type of unsignalized Intersections, which are two ways four lanes in majors and two ways two lanes in minors (i.e. 4 x 2 T Intersections). It is found that some drivers' gap-acceptance behaviors change along with their waiting time. It is also found that the precision of the traditional prediction model for critical gap could be improved if waiting time is considered, which implies that drivers' gap acceptation behaviors have much to do with drivers' waiting time. The waiting time is longer, and the possibility of taking risks to accept the small gap is larger. The quantitative model was also developed to explain the relationship between values of accepted gap and waiting time.The conclusions of paper are expected to be useful in safety control design and discussing safe driving behavior for unsignalized intersections.