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

农村地区的小城市和乡镇依赖当地的道路网络，改善这些网络以促进社会经济活动是必不可少的。传统的道路规划方法适用于原始分布路网的设计，而车辆OD调查等道路交通普查为这类规划提供了基础数据。然而，人口普查数据总是适用于农村地区的小城镇。城市中交通区域的大小可能与调查区域不一致。小城市和乡镇可用的分析方法尚未得到研究。本研究计划旨在发展一种分析方法来描述和估计当地城市的网络交通流量，以支持道路网络规划过程。主要研究课题分为两部分。首先，对基于链路交通计数的OD估计模型进行改进，将道路交通普查观测到的OD矩阵转化为与城市区域大小一致的详细OD矩阵；其次，对实践中经验使用的两阶段交通分配方法进行了改进，用于估算城市交通流量。将OD估计与流量分配相结合的方法应用于爱媛县西条市和新滨市的网络。数值算例表明，该方法对于缺乏丰富交通调查数据的农村城镇路网规划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.