Development of Combined OD Estimation and Traffic Assignment Method for Road Network Planning of Small Cities and Towns in Rural Areas.

农村地区的小城镇依赖于当地的公路网，改善这些公路网对于促进社会经济活动是必不可少的。传统的公路网规划方法主要用于主干道的路网规划，而小汽车OD调查等道路交通普查为此类规划提供了基础数据。但普查数据始终适用于农村小城镇。城市中交通区的这种大小可能与勘测区不一致。针对小城镇交通流的分析方法研究较少，本研究旨在建立一种描述和估算小城镇路网交通流的分析方法，为小城镇路网规划提供支持。主要研究课题有两个方面。首先，对基于路段交通量的OD估算模型进行改进，将道路交通量普查得到的OD矩阵转化为与城市区域大小相一致的详细OD矩阵。其次，对实际应用中的两阶段交通分配方法进行了改进，并将其应用于城市直达交通量的估算。结合OD估计和交通分配方法应用于爱媛县的西条和新滨市的网络。通过算例表明，该方法在交通调查数据不丰富的农村城镇路网规划中具有良好的应用前景。

Small cities and towns in rural areas are dependent on local road networks and it is indispensable to improve those networks for promoting socio-economic activities. Traditional road planning methods are useful for designing highway networks of primal distributors, and the road traffic census such as car OD survey provides fundamental data for those types of planning. However, the census data are always suitable for small cities and towns in rural areas. This size of a traffic zone in a city may not be consistent with a survey zone. Analytical methods available for small cities and towns have not been studied.This research project aims to develop an analytical method for describing and estimating network traffic flows in local cities in order to support road network planning precess. Main research topics are two folds. At first, the OD estimation model using link traffic counts is improved for transferring the OD matrix observed by the road traffic census into a detailed OD matrix which is consistent with the zone size of a city. Secondly, the two stage traffic assignment method empirically used in practice is reformulated for estimating through traffic in a city. The combined OD estimation and traffic assignment method is applied to the networks in Saijo and Niihama cities of Ehime Prefecture. Through numerical examples, it is found that the performance of the proposed methods is promising for road network planning in rural cities and towns without rich traffic survey data.