Simulation Research On Capacity Of Urban Expressway Confluence Area

With the gradual development of urban road systems,most cities have built expressways,but there are few studies on expressway confluence areas,especially in terms of traffic capacity,which leads to insufficient theoretical support in expressway planning and design and traffic management and control.The current research methods of capacity are mainly based on model calculation and actual data estimation.These methods have a series of problems such as complicated formula derivation,low accuracy,and difficulty in obtaining data.To this end,this paper builds a method that uses simulation technology to obtain the headway time,combined with data regression to calculate the capacity of expressway confluence area,analyzes the error through the measured speed and flow of traffic flow and the simulated value,and refers to the estimated capacity to verify the effectiveness of the research method in this article.This article starts with the basic concepts and influencing factors of the capacity of expressway confluence area,summarizes the general combination of basic traffic flow parameters in the confluence area,analyzes the common research methods of confluence area capacity,and determines the data regression model as the method of calculating capacity.Select a typical confluence area in the west section of the South Second Ring Road in Xi’an as the research object,choose a reasonable collection time and place by field photography and collection,and compare 5 minutes as the statistics by comparing the characteristics of the traffic data at different statistical time intervals Data collection is performed at intervals,and after data processing,traffic flow data is obtained,which provides basic parameters for later calculations and simulations.Then,based on the real data,research and analyze the vehicle driving characteristics and traffic flow statistical characteristics of the expressway confluence area,and obtain the traffic flow speed and flow changes in different lanes and different locations in the confluence area,and different inflow behaviors.The impact on the main line traffic speed.Based on the measured datas,the relationship between the three parameters of traffic flow speed,flow and density is discussed.It is concluded that the traffic flow model basically conforms to the Greenhills model.The extrapolation of the speed-flow relationship trend is used and the confluence area is calculated according to the flow frequency after the sudden change of speed The capacity of the main lane and ramp is estimated,and the recommended value of the capacity of the confluence area is finally determined to be 5250 pcu / h,which will provide a reference for the following simulation.With the paramics for simulation,build a road network model based on the actual road parameters in the confluence area,and use the field survey data to calibrate and simulate the parameters of the expected speed,expected acceleration and deceleration characteristics,vehicle type and traffic composition of the simulation model.The error analysis of the actual measured speed and flow rate and the simulation value shows that the error is within 5%,indicating that the simulation method is feasible.The vehicle headway is obtained through simulation,and the actual capacity of the confluence area is calculated to be 5300 pcu / h using a regression model,which is in good agreement with the estimated 5250 pcu / h.On the basis of research,this paper proposes traffic organization and control measures in the confluence area to provide a reference for the planning,design,operation,and control of the confluence area.