イギリスを中心とした都市モデル研究の動向

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Urban models attempt to describe the urban system using mathematical equations. They provide a simplified and abstract view of some aspect of the complicated urban system and deal with the allocation and interaction of activities or sectors in cities and regions. These mathematical models are developed to look at different aspects of the spatial distribution of activities within the urban system. The activities might be, for example, the distribution of residential population, employment, shops, working places; and the interaction might be the journey-to-work trip pattern or the journey-to-shop trip pattern. Thus urban modelling is a practical approach to urban analysis which seeks first to understand and describe the mechanisms which govern the structure and behavior of the urban system, and second to predict the outcome of future policy decisions.
The history of urban modelling research can be very roughly divided into two periods. Urban models of the first generation were desingned and implemented in the United States mainly in the late 1950's and the 1960's, which coincided with the launching of large-scale land use-transportation studies in major metropolitan areas. The realization that there existed a deep and subtle relationship between land use and transportation generated a demand for analytic methods. The most notable publication which did much to generate wider academic interest in the subject was Lowry's “A Model of Metropolis” published by The Rand Corporation in 1964. It is worth noting that these developments took place outside of geography. The period was one of great optimism for the future of model-based planning methods.
In Britain, drawing on the experience in the United States, the history of urban modelling dates back to the latter half of 1960's. British model building has developed mainly around one type of model, that first proposed by Lowry (1964). The major features of the second generation have been theoretical improvements of spatial interaction models and the development of calibration and estimation techniques. Especially the theoretical work into spatial interaction pioneered by Wilson(1967) has been extremely useful in providing much improved formulations of the sub-models in the integrated operational urban models.
This paper attempts to sketch the development of urban modelling research in Britain, and to explore the structure of urban modelling as a research specialty in terms of the limited perspective yielded by citations. Citation analysis is a bibliometric method using reference citations found in scientific papers, and it is a useful method in the sociology of science in order to reveal the structure of community of researchers engaged in a particular research specialty. The set of papers selected in this paper is defined by those which cited Lowry (1964), and weve published up to 1986 in Environment & Planning A and Regional Studies and, articles and books closely related with urban modelling. Adopting this criterion gave a set of 88 papers. These papers are listed in the Appendix, and the recording the citations made by each paper in the set to other papers in that set is shown as an incidence matrix in Figure 3.
After this citation matrix has been transformed into not the correlation matrix but the cross-product matrix standardized by sum of squares, factor analysis was applied to it. Using the standardised cross-product matrix in conducting the factor analysis may be an appropriate procedure for the binary date matrix (Yano, 1985). The matrix shows the linkage between source papers through co-cited papers.
The factor analysis produced eleven factors corresponding to research topics in urban modelling, accounting for 64.9% of the total variance. The results of the analysis are summarized in Figure 4.