Micro Modeling Of Urban Intersections With Multi-flows Based On Conflicting-point Detection

ABSTRACT:Under the heterogeneous traffic condition, motorized vehicles, non-motorized vehicles and pedestrians interfere with each other seriously at intersection. Intersection becomes a complex system which has got multi motion agent and competite for road resource with each other. Some models, such as car-following model, two-dimension cellular automation model, and multi-agent model, are quite difficult to depict the conflicts and game process when apply to intersection simulation. Therefore, it is very necessary to research on the simulation model which can depict heterogeneous traffic exactly.Based on the careful observeation and existed research achievements on micro-simulation of intersection, the disseratation proposes a new continuous micro-simulation model of intersection which is named Conflicting-point Detection model (CPD model) from a new angle of view. Main works and conclusions of this dissertation are summarized as below:(1) Mixed considering the thoughts of vehicle following model, Cellular Automation (CA) model and mutlti-agent model, a continuous micro simulation model for mixed-traffic intersection with conflict points as the virtual research subject-Conflict-point Detection (CPD) model, is established. This model has the characteristics of displacement continuity, containerness and openness, and can call a variety of mathematical models as simulation rules.(2) Unlike the previous simulation models, which only take the moving subjects or discretespace as the researching objects, the virtual conflict-point is selected as the studying object, at the same time, the concepts of conflict-point gaming rule, system dynamics function are proposed. Through the cooperation, the comprehensive "predecide-finaldecision" process of multi-subjects can be converted to the "preview-reaction" process of virtual conflict-points, and has counteractions to the moving subjects parting in the game. So, the "stimulus-response" process can be more micro-decribed and detailed. Therefore, the new model has more advanced capability for describing the conflict behaviour between vehicle and non-vehicle traffic inside the intersection than the previous models.(3) Based on the CPD model, a new intersection topological description modal with conflict-points as the network nodes, is come up. Moreover, this new modal can dynamicly integrate several moving subjects forming the dynamic network, prepare for the micro description of conflict between different subjects gaming for the way right.(4) Based on the characteristic of CPD model, conflict-points gaming rules and system dynamics function, a single-step two-stage simulation is built. Then the right-of-road gaming behaviors and influence of gaming results on all moving subjects inside the intersection are described hierarchically. Therefore, from a new angel the nature of conflict is described detailed inside the micro-length.(5) According to the characteristic of CPD model, coordinating with the parallel method of P2P grid calculation structure and large-scale parallel calculation using advanced general graphics processor, a hierarchical description of network forming by road sections and intersections is put forward. Then, the parallel simulation framework and algorithm is proposed, and the calculation efficiency is calculated. Result shows that the algorism based on GPGPU has at least 5 times advantage to the traditional algorism with based on only CPU architecture, and the grid based architecture can also bring obvious promotion in the case of simulation in a large-scale traffic network.