交通仿真系统中车辆出发时间分布模式研究

Study on the vehicle departure time distribution mode in traffic simulation systems

对于交通仿真系统尤其是实时交通仿真系统而言,仅在具有准确的动态OD矩阵输入,并且每个动态OD流量中车辆出发时间间隔的分布模式有可靠估计的前提下,这些系统才可能准确地复现实际的交通状态.迄今尚不存在任何针对车辆出发时间分布模式的研究.将动态OD估计的每个时段细分为若干更小的等长度时间间隔,采用"直方图"逼近动态OD流量沿着这些子时段变化的轨迹,以便更准确地刻画车辆出发时间的分布模式;建立了OD流量在每个子时段内的分配比例的参数估计模型,并采用高效率的同步扰动随机近似(SPSA)算法对估计模型进行优化求解.针对美国加州I805号高速公路上一段拥挤的网络进行测试,表明本文的方法是十分有效和高效率的.

For existing traffic simulation systems, especially for real-time ones, only given correct dynamic OD matrix input and reliable estimation of vehicle departure time distribution for each OD pair, the traffic simu- lation systems can replicate the real traffic accurately. So far, no research has been performed for the estimation of vehicle departure time distribution mode. In this paper, each OD estimation interval is subdivided into some shorter time spans with same length along which each OD flow curve can be approximated using a series of histograms. In this way, more accurate vehicle departure time distribution mode can be characterized. Also, a parameter estimation model of OD flow distribution ratios within sub time spans of each OD estimation interval is established, and the hight efficient simultaneous perturbation stochastic approximation algorithm（SPSA） is adopted to solve the parameter optimization problem. The actual test using the traffic detector data of I805 freeway in California of the U.S. shows that the proposed method is very effective and efficient.