Semi-Actuated Signal Algorithm Study For Two-Phase Signalized Intersections

In two-phase signalized intersections of many domestic median cities, especially in major road & minor road intersections, the arrivals of vehicles are unstable,and many pedestrian-bicycle groups exist . If the pretimed signal control mode is selected, partly green time will be wasted, and green time efficiency of whole intersection will decrease a lot also. If actuated signal control mode is selected, left-turn vehicles are affected heavily by the pedestrian-bicycle groups when crossing the crosswalk, even part left-turn vehicles can not pass through the intersection normally. Current actuated control algorithm is not fit to the signal control demand, so it is necessary to study the semi-actuated signal control algorithm.This paper determines the research content of this paper, based on the summary of the research fruit about actuated signal control and gap-acceptance theory.Then considering the current condition, data is collected in two-phase signalized intersections by using the video and artificial observation method, the definitions of"pedestrian-bicycle group"and"left-turn critical gap to cross pedestrian-bicycle group"are defined, the conflict characteristic of left-turn vehicle with pedestrian-bicycle group is analyzed, the gap types are classified, the"Gap- Projection Theory"method is proposed,and gap observation standard is determined. Rejected gap and accepted gap are obtained by using the Simi Video Software under the determined gap observation standard, average accepted gap and critical gap is computed with RAFF method.According to the balance principle of the left-turn vehicles arriving and departing, the new minimum green interval algorithm model is built by combining with the ideas of queue service time model which mentioned in HCM2000. This paper does gap-acceptance study with collected data in Fule Street & Yingbin Road of Huairou District in Beijing, semi-actuated signal timing plan is computed with the new algorithm model, and is validated with index of the control delay and Level of Service (LOS) in intersection.