Research Of Traffic Flow Simulation In Special Sections Of Freeway

Facing up the situation of increasing road resources in order to meet the increasing traffic demand only by relying on the way to traditional newly-built or expansion and the status of increasingly serious traffic congestion, by taking the special sections of freeway as the research objects, based on analysis of the traffic flow characteristics of special sections, the traffic flow characteristics and spatial evolution mechanism of special sections were studied by using the improved cellular automaton theory, the aggregation and dissipation process of traffic flow were simulated in the situation of different operation rules and limit conditions.For the specific situation, the corresponding management and control strategies were proposed in this dissertation, it can provide theoretical basis and decision-making proposal for highway decision-makers to regulate the temporal distribution of road network flow, relieve the peak traffic congestion and realize the optimization of road resources.The research content under this article mainly covers:An introduction of background, significance and ideas of this dissertation. The theoretical models, emulation methods as well as management and control strategies were employed to research the freeway traffic flow, combined with the status of present traffic,analyzed the research contents, basic ideas and the implementation methods of the dissertation.Review on correlation theory of freeway traffic flow. The theories and models of traffic flow were discussed separately from macroscopic, mesoscopic and microcosmic, the theory of traffic wave was analyzed from the perspective of origin, principle and development, the cellular automaton theory was summarized separately from the definition, characteristics,classification and application.An analysis on characteristics of freeway traffic flow and the establishment of cellular automaton model. Considering the characteristics of the basic section traffic flow, based on the theory of traffic wave, the maintenance and tunnel sections traffic flow of freeway were studied. This dissertation takes a bidirectional and four lane freeway as an example, the traffic flow operation state of sections were redefined, through analysis of the temporal and spatial distribution characteristics to reveal the transformation mechanism between traffic state of the key nodes of special road section. A temporal effect model was established which related with closed lanes, maintenance time as well as traffic flow of upstream, the length of waiting vehicle queue and the influence time of the special road sections were deduced. On this basis,an improved traffic flow model is proposed based on cellular automaton(CA) considering the operation rules and the limit conditions, it provides pre-conditions for the next research.Study on traffic flow simulation in special sections of freeway. The time-space evolutionprocess of basic and special section traffic flow in freeway is simulated based on the improved CA model. As for the basic sections, the simulation results showed that with the increase of traffic density, the traffic congestion becomes more seriously. During the simulation of the maintenance section, different type of lanes and different proportion of vehicles, are considered to research respectively, the results showed that construction and maintenance have a great influence on the freeway traffic flow and considerably on traffic flow density within 0.05 to 0.45. And the influence of closed lane on traffic flow on fast lane is less than on slow lane. Meanwhile, the longer the blocking time and the length of closed lane, the greater the influence of traffic flow is. For the tunnel sections, different density of arrived vehicles and different proportion of mixed vehicles, are considered to research respectively, the results indicated that the light and shade effect in exit and entrance of tunnel has a great influence on the freeway traffic flow, one of the solutions is to increase the probability of the vehicles in the tunnel exit. Meanwhile, the more proportion of mixed vehicles and the length of tunnel, the less efficiency of traffic flow is. Finally, this dissertation make some countermeasures and suggestions according to the shortcomings exist in the traffic management and control strategies, and it can offer support and help for the operation management of modern highway.