Analysis And Timing Optimization On Traffic Capacity Of Urban Arterial Weaving Section Under Lane Signal Control

The weaving section is an important part of urban artery roads.Due to the complicated lane change and driving behavior in the weaving section,it is easy to form a bottleneck of constant congestion in unber area.As the traffic demand increases,the traffic pressure in the interweaving area becomes more and more serious.Not only the capacity of the interweaving area is greatly limited,but the influence of the backflow and spread of the traffic flow on the main road is also serious.Faced with increasingly saturated traffic volume,ramp control and variable speed limit control are important means to alleviate congestion in the weaving section.However,ramp control can only be applied to simpler weaving sections,and the control effect not fit well with complex interweaving operating environment,and currently there are few studies on the capacity of the weaving section under the the lane signal control.Therefore,this paper proposes a capacity calculation model for the weaving section under the lane signal control.The objective function is to maximize the weaving capacity and the constraints are to keep safety space headway in a signal cycle and the queue lengths at the entrance lanes.It plays an important part in evaluating,optimizing and improving the control mode of the weaving section.First of all,this paper summarizes the factors affecting the operation of the interweaving zone and the assessment methods of the interweaving zone's traffic capacity,and analyzes and summarizes the existing research methods of the interweaving zone's traffic capacity.Based on the analysis of the existing interweaving zone's ramp control strategy,this paper puts forward the missing points of the existing research,and on this basis,determines the research direction and content of the interweaving zone's traffic capacity under lane control.Secondly,according to the research requirements of this paper,a data acquisition and processing scheme for the interweaving area of main roads is formulated and implemented.Through traffic investigation,the time-varying characteristics of traffic flow characteristics(speed,flow rate,occupancy rate)at the upstream of the entrance to the interweaving area are analyzed,and the critical state of traffic congestion in the interweaving area is studied,providing data basis for judging the implementation of lane signal control.In addition,through a large number of measured data,the characteristics of car following and lane changing in the interweaving area of main roads are studied,which also provides a basis for the construction of the following simulation road network.Then,according to the mismatch of the entrance lanes and the reduction analysis of the traffic capacity of the interweaving area caused by the forced lane change,this paper puts forward the signal control method of the interweaving area merging into the lane to control the incoming traffic volume and the interweaving ratio,adopts the interweaving reduction factor and the basic parameters of the signal control,constructs the calculation model of the actual traffic capacity of the interweaving area under the lane control,and calibrates the model coefficient based on the measured data.On this basis,the signal control scheme under different phases in the interweaving area is constructed by using matrix variables.Taking the actual traffic capacity in the interweaving area as the objective function and the interweaving ratio,phase control scheme,entrance lane queuing and cycle duration as constraints,the optimal signal timing model for the entrance lane is proposed.The critical speed and critical occupancy rate of the entrance lane are used as control variables to determine the implementation discrimination of lane control.Finally,taking the interweaving area near Yuanjiagang as the research object,this paper applies the model to analyze the two-phase and three-phase lane control schemes,and constructs a simulation to compare the three schemes of two-phase optimal,threephase optimal and uncontrolled.The results show that the actual traffic capacity and overall operation situation of the interweaving area are obviously improved after the entrance lane signal control is adopted.