Research On Signal Control Of Roundabouts Under Flow Difference

In the low traffic requirements,the vehicles can travel continuously and freely through the roundabout,this way can make to eliminate the conflict point and improve the safety of driving.But in recent years,a simple uncontrolled roundabout is no longer applicable for the the continuous growth of traffic.The method of controlling the secondary parking of the left turn at the roundabout is proposed by Yang Xiaoguang ect.Of Tongji University.This method can not only expand the capacity bottleneck of the roundabout,make the left turn traffic be able to queue up twice in the ring space,but also improve the traffic capacity of the roundabout,reduce traffic delays.However,the left turn of the secondary control method is generally symmetrical release of the two-phase signal control,the probability of flow in the inlet direction of the roundabout is exactly the same.When there is a difference in the flow rate to the two inlet channels,the control scheme of the symmetrical release is used,which makes the internal loop in the same phase in the direction of the incoming direction.In the direction of the input signal Green time using green uneven.Therefore,it is necessary to study the signal control in the case of large-scale circular intersections in the presence of different flows at the intersection of the secondary control of the circular intersection.In this paper,we introduce the existing symmetric release control scheme for the left turn quadratic signal control of the large roundabout,and the existence of the effective green time utilization and the lack of effectiveness of the loop space utilization in the case of the existence of the flow difference The problems were analyzed and summarized.For the convenience of subsequent comparative analysis,the specific calibration process of the signal control scheme is described in detail for the specific application conditions of the conventional symmetrical release left turn quadratic signal control scheme.The main innovation of the paper is that according to the situation of the lack of loop space in the symmetrical direction control scheme,a control method is proposed to utilize the residual loop space and advance the flow direction of the high flow direction.And the detailed analysis and optimization steps of the control strategy of advance release control scheme are analyzed in detail.In the process of implementing the control scheme,the overall situation of each phase time of the relevant import road is analyzed and the corresponding import traffic is corrected.The green time of the second parking line,the green time in each phase,the time of the yellow light,the time of the whole red,and so on.The calibration process is related to the conventional symmetry.The final model calibration and subsequent optimization of the corresponding signal control parameters are carried out,and the process of proposing and determining the whole advance release control scheme is completed.Finally,through the establishment of an optimal control program evaluation system.Based on the VISSIM simulation technique,the traffic data of the circular intersection in Qujing are investigated and reasonably predicted.The advance release control scheme is compared with the symmetric release control scheme,which indicates that the advance release control scheme can shorten the signal cycle.In the case of different flow differences,the simulation analysis is carried out according to two different signal control schemes.The comparison between the two methods of symmetric control release control method and optimization control method is given to the example intersection.It is shown that the optimal control scheme has Superiority and applicability.