Weaving Traffic Flow Modeling And Characteristic Analysis Under Heterogonous Vehicles Condition

ABSTRACT:Weaving section is an important part of urban expressway road network. In weaving section, the traffic is disordered since the drivers need to change lanes in a limit space. At the same time-, there are many vehicles which have large sizes and move slowly on the road, the efficiency of weaving section will be reduced severely when they change lanes. Analyzing the operation characteristics of weaving section under heterogeneous conditions is meaningful to design efficient traffic control model.In this paper, heterogonous vehicles condition, including small fast and large slow vehicles, is taken into account and a revised cellular automata based weaving section model is proposed. Vehicle characteristics in weaving section, isolated on-ramp and isolated off-ramp are analyzed separately. And the capacity of weaving section is intensively investigated under heterogeneous vehicles condition. At last, the effect of side-road control is studied. The following are the main results:Firstly, the cellular automaton model is used to model the type A weaving section under the condition of heterogeneous vehicles. We analyze the vehicle characteristics in the system of weaving section and get the conclusion that the larger the proportion of large slow vehicle, the more serious the influence on the efficiency of weaving velocity. The system is easier to achieve congestion state and the maximum saturation flow decreases. And when there are fewer vehicles in the weaving section, the increase of large slow vehicles will not cause a great impact on the weaving section. But when the more vehicles in the weaving section, it would seriously reduce the vehicles’operation efficiency of weaving section.Secondly, various impact factors on weaving section are analyzed and the capacity of weaving section under the condition of heterogeneous vehicles is investigated based on the volume ratio and weaving ratio. The capacity of weaving section decreases seriously with the increase of volume ratio and the proportion of large slow vehicle. The capacity of weaving section model under the condition of heterogeneous vehicles is calibrated and from the result we get a better fitting result. It can be used to analyze the capacity of weaving section.Thirdly, the effect of side-road control on the off-ramp traffic is investigated. When the side-road has a little effect on the off-ramp vehicles, the off-ramp vehicles can enter the side-road in a relatively short time, which improves the operation efficiency of the weaving section. But if there isn’t side-road control, the side-road has a great influence on the off-ramp vehicles, the vehicles cannot be out of the weaving section in time, which results in heavy congestion in weaving section.