Research On Critical Characteristics Of Two-Lane Traffic Flow Based On Three Phase Traffic Theory

In this paper,we investigated the Cellular Automaton models for highway traffic flow in the theoretical frameworks of Three-phase Traffic Theory.We summarized the main points of the research as following:(1)First of all,this paper introduced the background and the methods of traffic flow and described the critical characteristics between different traffic phases and basis hypothesis after comparing the fundamental diagram approach and the three-phase traffic theory.(2)By enumerating the several classical cellular automata models under theoretical frameworks of three-phase traffic theory,we pointed out the limitations of the models from the actual traffic and theory analysis angles and then established a new cellular automata model.This model divided the operation of road traffic flow into two parts: speed adaption behavior under safety condition and vehicle disturbances.Because of introducing the concept of synchronization distance to the speed adaption,the vehicles were running in the range of distance.The speed adaption maintained a steady traffic flow,and then achieved a synchronized flow.Vehicle perturbation mainly considered the delay of vehicles.To cause acceleration or deceleration disturbing behavior,they would become less sensitive to external incentives when the vehicles keep the running states over a certain period of time.We solved the steady state solution of the model before performing the simulation experiments.The steady state solution was similar to the traditional models.Then use numerical simulation to study the various characteristics of the model.The results showed: we could simulate free flow,synchronized flow,wide moving jam and different first-order phases between them.The data were in accordance with the basic hypothesis and analysis of the three-phase flow theory by analyzing the data measured by the virtual probe.The self correlation and cross correlation analysis of the traffic parameters of the traffic flow in the synchronized flow did not exist the long-range correlation function,which was same as the basic assumption of the synchronized flow.So we believed that this model was a traffic cellular automaton model under the framework of three phase traffic flow theory.(3)Then we extended the above model and processed a two-lane traffic flow model.In actual traffic,the main differences between the multi lane and single lane were the lane change rules.Therefore one of the key researches in the two-lane traffic flow was the effect of lane changing rules.In our model,the rule of lane changing was one kind of asymmetric rules,which was divided into two parts.At the safety distance part,we judged the lane changing conditions by considering the adjacent roads and the gap of vehicles speed in front and behind.Firstly,in reference to Kerner’s assumption for multi-lane traffic flow,we defined a concept of lane changing probability to study the lane changing behaviors for the impact of traffic flow.In the lane changing probability and road density figures,we found that the lane changing probability of free flow was always greater than the synchronized flow.And the changing possibility was randomly distributed in a two dimensional region which was consistent with the synchronized flow features.In the areas of the wide moving jam,the possibility of lane changing was reduced to 0.These views met Kerner’s hypothesis.So it could be proved that substantial reduction of changing possibility was one of the reasons about phase transformation.Secondly,in order to study the influence of micro lane changing behavior on the road traffic flow and the relationship with the phase transition,we analyzed the vehicle trajectory.Lane changing could play a dual role in traffic flow: maintain free flow or in contract lead to traffic congestion at the bottleneck.