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Formulation of Traffic Estimation Models by Observed Link Flows and Comparative Study of Their Accuracy

通过观测链路流量建立流量估计模型及其精度比较研究

基本信息

批准号：
60550372
负责人：
IIDA Yasunori
金额：
$ 1.15万
依托单位：
Kyoto University (1986)Kanazawa University (1985)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550372/
关键词：
Observed Link Flows OD Matrix Estimation ネットワーク

项目摘要

The existing models for estimating OD matrix from traffic count data on links have been formulated in different ways depending on the theoretical grounds. The basic idea common to these kinds of models proposed so far is that the most likely OD matrix can be produced by obtaining a consistency or a goodness of fit between the esimated and the observed link flows. In most of the models, moreover, a closeness measure between the estimated and the outdated OD matrices is incorporated into the formulation. It has not known, however, what form of the model formulation is the most appropriate for practical use. On this context, we make comparative study on the different model formulations and examine the model properties concerning the prediction errors caused by various kinds of noises or errors in the prior informations or the given data. The models presented in this paper are formulated in terms of minimization of the sum of square errors between the estimated and the observed or the outd … More ated flows, which can be considered as an approximation of the model formulations for the exixsting models derived from such as the entropy maximizatiom principle or the most likelyhood method. The merit of this simple model formulation is that the estimates of the elements of an OD matrix can be easily obtained by simultaneous linear equations, which is unnecessary to perform iterative procedure as seen in the many existing models. In addition, since the generation trips from nodes only are regarded as unknown variables in the model formulation, we can achieve outstanding savings of necessary computer memories.In this comparative study on the model properties through the numerical analyses, the follwing three types of model formulations are considered. Model A is formulated by minimization of the sum of square errors between the estimated and the observed link flows only, Model B by that of the sum of square errors between the estimated and the outdated generation trips at nodes under the constraints of consistency of link flows, Model C by that of the total sum of square errors in the generation trips at nodes and in the link flows. For these three types of model formulations, we examine and compare the properties concernig the prediction errors by fluctuations in OD pattern, variations in route choice probabilities, noises in observed link flow data and differences in the number of observed links by using hypothetical data made artificialy. The aim of this research is to find out the most appropriate model formulation for practial use through these numerial analyses, which can yield the more accurate and the more stable estimates of OD trips even if there exist some degree of errors in the given and the observed data. Less

现有的根据路段交通量数据估算OD矩阵的模型是根据理论依据以不同的方式建立的。到目前为止提出的这些类型的模型的基本思想是，最可能的OD矩阵可以通过获得估计的链路流和观测的链路流之间的一致性或拟合度来产生。此外，在大多数模型中，估算的OD矩阵和过时的OD矩阵之间的贴近度被纳入公式中。然而，还不知道什么形式的模型公式最适合实际使用。在此背景下，我们对不同的模型公式进行了比较研究，并考察了由先验信息或给定数据中的各种噪声或误差引起的预测误差的模型性质。本文所提出的模型是以估计值与观测值或OUTD…之间的平方误差和最小为准则的。更多的流动，这可以被认为是现有模型的模型公式的近似，这些模型是由诸如熵最大化原理或最大似然法等派生出来的。这种简单模型的优点是，OD矩阵元素的估计可以很容易地通过联立线性方程获得，而不需要像许多现有模型那样进行迭代过程。此外，由于在模型公式中仅将节点的生成行程视为未知量，因此可以显著节省必要的计算机内存。在通过数值分析对模型性质进行比较研究中，考虑了以下三种模型公式。模型A仅由估计潮流与观测潮流之间的平方误差之和最小化，模型B由节点潮流一致性约束下估计出力与过时出力之间的平方误差之和最小，模型C由结点和路流中发电出行的平方误差总和最小构成。对于这三种模型公式，我们检验和比较了OD模式的波动、路径选择概率的变化、观测路段流量数据中的噪声和观测路段数目的差异对预测误差的影响。这项研究的目的是通过这些数值分析找出最适合实际使用的模型公式，即使给定数据和观测数据存在一定程度的误差，也可以得到更准确和更稳定的OD出行估计。较少