城市道路U形转向交通流特性模拟分析

以NaSch模型为基础建立设置U形转向的路段交通流模型,对其特性进行模拟分析. 结果表明,U形转向路口对交通流影响显著,会导致在较小进车概率时发生自由流状态到拥挤状态的相变,相应的临界流量也随之降低. 设置双U形转向系统的相变、临界流量等交通流特性与单转向系统具有明显差异,其系统效率较高. 在实际交通规划与管理时应避免设置单转向系统,以减小U形转向的负面影响. 关键词： 交通流 元胞自动机 U形转向 相变

The influence of U-turn movement on the dynamics of traffic flow

U-turn movement is a common form of traffic organization in urban streets. A traffic flow model for U-turn movement based on the NaSch cellular automaton model is proposed to simulate and analyze the dynamics of U-turn movement. The results indicated that the U-turn movement has significant effect on the traffic flow, and it is a typical bottleneck. The U-turn movement can cause phase transition at small probability of vehicle generation and the critical flow also decreases obviously. The system with two U-turn movement is different from the system with one U-turn movement in traffic features such as phase transition and critical flux. The one U-turn system has a good performance. It is suggested that the system with a couple of U-turns may help mitigate the negative effect of U-turn movement in traffic planning and management.