Research On Capacity Of Left Turn Lane At Signalized Intersection

City signalized intersection is the main place of traffic conflict，while theleft-turning flow is one of the primary factors of traffic conflict. The left-turning flowhas an important influence on capacity of the intersection. In the traffic managementand organization of an intersection, it is very important and difficult to manage andorganize the left-turning flow. The capacity of entire signal controlled intersection hasbeen extremely restricted by left-turning flow.In order to improve the capacity of signal controlled intersection, this thesiswhich based on the existing research results and the measured data used the method oftheoretical analysis and traffic simulation to study the traffic flow characteristics andcapacity of left turn lane with waiting area in signal intersection. The results of thisstudy will provide the theoretical basis for signal control intersection planning, design,transformation, traffic organization, signal timing, evaluation of the traffic operation,and lane setting.Based on the study of traffic operating characteristics and the signal controlcharacteristics of a left turn waiting zone in the intersection, signal control strategy ofa left turn lane had been provided. And a traffic simulation model of signalizedintersection was established. According to the measured data and traffic simulationmode, this thesis studied the influence of left turn waiting area size, opposite rightturn flow, exit lanes number, the proportion of large vehicles and turning radius on thecapacity of left turn lane. The primary aspects are as follows:(1) The relation curvebetween the size of left turn waiting area and the saturation flow rate had beenestablished, and the correction model of the left turn lane saturation had been given.(2) Under the condition of different exit lanes number, this thesis analyzed theinfluence of opposite right turn flow on the left turn lane saturation flow rate; theresults showed that: when the intersection exit lanes number are2lanes, the oppositeright turn flow has a great influence on the left turn lane capacity.(3) This thesisanalyzed the influence of the turning radius on the left turn lane saturation flow rate.And, the correction model had been build between saturation flow rate and left turnradius.(4) The influence of the traffic composition on left turn lane saturation hadbeen studied. And, the correction model of left turn lane capacity had been built bythe proportion of large vehicles.(5) Finally, according to the road and traffic condition of Changsha, this thesis provides a model to calculate the capacity of theleft turn lane with waiting area in signal intersection.