Nonstrict Priority Left-Turning Maneuvers with a Permitted Phase at Signalized Intersections: Empirical Study in China

AbstractThe study investigated the analysis of nonstrict priority left-turning vehicle maneuvers with a permitted phase at signalized intersections, based on field observation at four sites (one with a permitted phase and the others with protected phases) in Changchun, China. Trajectory densities at four cross sections along the turning paths were collected, and the concept of a left-turn group was proposed for discussing the maneuver. Then, analysis was conducted by means of clustering and probability distribution fitting. The results revealed that (1) a significantly wider trajectory distribution appears in permitted left-turning maneuvers than in protected phases; (2) four different maneuvers exist for the leading vehicle of a left-turn group; and (3) following time intervals in a left-turn group have a leptokurtic distribution that can be best fitted by the log-logistic and lognormal models. This study provides a better understanding of the nonstrict priority left-turning maneuver with a permitted phase with respect to operational performance, and offers the basis for further study on permitted left-turning streams, such as their capacity and delay.