论文部分内容阅读
为准确掌握高速公路交通流的运行状态及变化规律,给驾驶人和高速公路管理者提供科学决策依据,通过分析传统交通流计算模型存在的不足,对现有高速公路交通流状态划分方法和基于尖点突变理论的交通流模型进行改进,并引入混沌状态和突变区间的概念,同时添加大车混入率作为改进后的模型参数,得出不同大车混入率下混沌流状态、自由流状态和非自由流状态下的判别标准。以八车道高速公路标准路段为例,借助VISSIM交通仿真软件模拟车流的实时运行状态及变化过程,计算获得仿真情形下不同交通流状态的判别标准和方法。通过对典型高速公路代表性路段实测数据的统计分析,验证了判别标准和方法的合理性与可行性。研究结果表明:交通流在自由流和非自由流状态之间转变时,存在着一种短暂的突变,呈现出一种混沌流的状态;大车混入率对行车速度和时间占有率影响明显,可以对应获得混沌流、自由流和非自由流状态的判别标准;将仿真所获得的交通流状态界定标准与中、美高速公路服务水平划分标准进行对比,自由流状态处于二级或C级及以上服务水平,而且对自由流服务水平的标准要求更高。该方法对于高速公路运营管理、养护路段划分、安全性评价等具有科学、便捷、实用、可行的实际意义。
In order to accurately grasp the operation status and variation rule of expressway traffic flow and provide drivers and managers of expressway with scientific decision-making basis, by analyzing the existing problems of traditional traffic flow calculation model, Cusp catastrophe theory, and introduced the concept of chaos and mutation interval. At the same time, the mixed rate of carts was taken as the improved model parameters, and the chaotic flow states, free-flow states, Discriminant criterion in non-free-flow condition. Taking the standard section of the eight-lane expressway as an example, real-time running status and changing process of the traffic flow are simulated by VISSIM traffic simulation software to calculate the different standards and methods for judging the different traffic flow states in the simulation. Through the statistical analysis of the measured data of representative expressways of typical expressways, the rationality and feasibility of the discriminant standards and methods are verified. The results show that when the traffic flow changes between the free flow and the non-free flow state, there is a sudden mutation, showing a state of chaotic flow. The mixed ratio of the cart has an obvious influence on the driving speed and the time share, The criteria for judging the condition of traffic flow obtained by the simulation can be compared with that of the expressway service level in China and the United States. The free flow condition is at the second or C-level and the second is at the free flow state. Above the level of service, but also higher standards of free flow service standards. The method is scientific, convenient, practical and feasible for the highway operation and management, the conservation of road sections, safety evaluation and so on.