Study Of Congested Traffic Flow Features And Mechanism In Expressway Merging Area

In recent years, with the rapid development of China’s economy, the rising proportion of car trips, and the supply of transport infrastructure is lagging behind, the contradiction between supply and demand continues to grow, which caused the growing problem of urban traffic congestion, traffic congestion has become the world’s major city hot issues resolved urgently. Urban freeway is the main backbone of the urban road network, urban transport aorta, but traffic congestion has become increasingly prominent in recent years, has seriously affected the fast road traffic efficiency play.First, based on traffic measured data to study the expressway ramp junction generated in congestion, traffic flow diffusion and dissipation of the whole process time-varying characteristics, namely fast road traffic flow parameters:flow, speed and density varies with the characteristics of time, as well as the relationship between the characteristics of traffic flow parameters, which summed up the general rules of the road congestion during rapid changes in traffic flow; and based on traffic flow characteristics analysis method to determine Freeway Traffic state transition time, and can be applied to freeway bottleneck congestion generation and dissipation of testing.Secondly, based on the Freeway traffic merge areas inside the operating environment, through a large number of microscopic observation data to study the operational characteristics of the confluence area of the vehicle, including:mainline traffic speed, acceleration lane speed, and the speed of import clearance relationship confluence point distribution, when the main line outside lane headway distribution, summed up the general rules of traffic running confluence region, and based on this proposed acceleration lane ramp merging area import vehicle models and driving distance model, so that the main line of traffic and confluence point distribution between the two variables to create a link; and from the speed and flow characteristics of the confluence of two aspects of the congestion zone of the data analysis, regression, leading to the occurrence of critical confluence zone congestion mainline, ramp flow curve theory Modeling ready.Finally, both from a qualitative and quantitative in-depth study of the freeway ramp junction congestion occurrence and diffusion mechanism. Qualitative aspects that influence the deceleration ramp vehicles change lanes and change lanes on the main follow-up is the root cause of traffic congestion occurs, and the use of transportation with Chi theory and wave theory to analyze the slowdown in with the team disturbance Chi state propagation methods and processes, the general rules drawn merge area traffic reduced capacity; quantitative aspects, to follow Chi theory and wave theory of traffic, plus the assumption, under the premise of constant deceleration velocity equal, the establishment of a ramp at low speed vehicle import After the main lane speed perturbation caused by the propagation model to develop a traffic flow condition occurs in the Breakdown of the communication process, and thus the main line is calculated at a certain level of traffic, the traffic flow to maintain a stable ramp import maximum acceptable flow.