Study On Left-turn Conflict Of Two Phase Intersections During The Peak Period Of Nocturnal Travel

Due to the improvement of the urban road traffic network and the surge of motor vehicle ownership in China,the traffic pressure in some old cities or residential areas is increasing rapidly.The intersection is usually controlled by two phase signal without dedicated left turn phase because of limited factors such as road space and environment,and left-turn conflicts are the most common phenomena at the intersection.Especially,the risk of left turn conflict is great in rush hour at night because of the factors such as bad sight distance of drivers and pedestrians,drivers are prone to fatigue,poor timing of signal lights,the safety facilities used to prevent traffic accidents at night are not complete or unreasonable,no traffic police on the scene at night and so on.Therefore,This paper focuses on the characteristics of the left turn traffic conflict in the two phase cross section at the peak of the night trip,and a traffic delay model in this model was established.It provides a theoretical basis for the optimal timing of the signal lights and the special phase setting of the left turn,so as to improve the left turn traffic conflict at night.The main contents and conclusions are as follows:(1)In this paper,the types of left-turn conflict at two-phase controlled intersection are analyzed,and the requirements and contents of traffic data,such as geometric parameters,circadian environment conditions,diurnal signal control parameters,diurnal traffic flow data and so on,are defined.The method of data acquisition combining video acquisition with manual method is determined,and the relevant requirements of data acquisition and the threshold value of PET for judging the severity of conflict are put forward.(2)The current situation of the left turn conflict in the two phase cross section of the day and night peak is investigated and the characteristics of the vehicle traffic at the peak period of the day and night are summarized,the characteristics of the non-motor vehicle traffic and the pedestrian traffic characteristics are summarized,and the left turn conflict occurring at the peak time of the night travel is compared to the left turn during the day.The conflict is more serious.In the area of the conflict point distribution,the conflict point distribution area at the peak time of the night travel is narrower than the day,and the conflict points are scattered and unevenly distributed,mainly in the middle of the intersection and the area near the crosswalk line.(3)From the four aspects of "person,vehicle,road and ring",the paper puts forward the measures to improve the left turn conflict at the night trip peak intersection,and points out that “According to the change of the traffic volume of high and low peak day and night,considering the delay time caused by the conflict,the signal light timing can be optimized reasonably.”,which is an important measure to improve the safety of left turn at night.In order to reduce the left-turn mixed conflict at the nocturnal peak two-phase intersection,a traffic flow delay model under the mixed collision of the two phases of the nocturnal travel peak is established,and the model is verified based on the measured data at the intersection.The relative error is 8.65,which further verifies the feasibility of the model.