A STUDY OF TRAFFIC FLOW PATTERNS IN THE URBAN AREA

Abstract

This paper is concerned with urban traffic flow patterns on the basis of investigation of the traffic flows in the central part of Kagawa Prefecture, Shikoku, in terms of trip purposes. The results of this study are as follows: Characteristics of traffic flow patterns based on trip purposes. On the whole, there are different traffic flow patterns based on the kind of trip purposes, and each pattern has its own specific characteristics. In journey to work, the important places of origin whichh have high factor scores in the principal component analysis (P. C. A.) are generally locatedd in the suburban districts, and the important places of destination which have high factor loadings in the P. C. A. are located in the center of the city. Therefore, the extent of traffic flow pattern involving journey to work is the largest of all. But this tendency varies with the degree of urbanization: a well-urbanized city has particularly important places of origin in the suburbs and those of destination in the center of the city respec-tively, while the particularly important places of origin are at the same time the particularly important places of destination in a poorly urbanized city. In journey to school, the extent of traffic flow pattern is comparatively small because the important places of destination are controlled by the location of schools and the important places of origin are in the neighborhood of these schools in accordance with the regulations of school district. In the trip for private purposes, the extent of traffic flow pattern is the smallest of all. Because the important places of both origin and destination are located very close to each other around a shopping district. These important places of destinationn consist of a part of the important places of destination for journey to work and for business purposes in a well-urbanized city. On the other hand, the important places of destination of the trip for private purposes are nearly at the same time the important places of destination for journey to work and/or for business purposes in a poorly urbanized city. In the trip for business purposes, places which have lively economic activities result in the important places of destination and they are not always consistent with the important places of journey to work. However, in a poorly urbanized city, the important places of destination of the trip for business purposes are at the same time the important places of destination for journey to work and both movement patterns are similar to each other around a shopping district. It should be noted here that, all-purpose movement patterns (the movement patterns set up without referring to specific trip purposes) are generally different from those set up in reference to there purposes. The degree of this differ-ence, however, varies with the progress of urbanization: when the degree of urbanization is low the all-purpose traffic flow patterns are similar to those for private or business purposes. Furthermore, the important places of destination of the all-purpose traffic consisting of a part of the important places of destination of the trip for business purposes plays an important role in the all-purpose traffic. The relationship between traffic flow patterns and urban structures can be summarized as follows: The number of trips to work which a district generates is closely related to the population of the district, and the number of trips which a district attracts is closely related to the number of people employed in urban occupations. Since the number of inhabitants of the suburban districts is generally larger than that of the center of the city and since the number of people with urban occupations in this section is larger than that of people who have occupations in the suburban districts, the particularly important places of origin are located in the suburbs, and the particularly important places of destination in the center of the city.