Parallel Program
Limits to Urban Growth and Urbanization *
A case study of Bangkok Problems
Orasa Suksawang and Hari Srinivas
Faculty of Social Sciences, Kasetsart University
Bangkok 10900, Thailand
Abstract
This paper suggests integrated teaching approaches of System Dynamics method for socio-
economic analysis, and Geographic Information System for spatial analysis, in examining,
evaluating and planning the limits to urban growth and urbanization of a city in the course of Urban
Planning by taking Bangkok city as a case study. The course is offered for graduate students in the
field of Social Sciences at Kasetsart University. Urban Dynamic Model applied in this study
includes interactions of population, capital investment of housing, industry and transportation;
economic development in terms of gross provincial product and loan interest rates, and land
subsystems. The model aims to illustrate problems of shortage and ineffectiveness of City Planning
Act which could not control disorderly urbanization and the over supplies of capital investment of
housing and industry. Historical patterns of spatial settlements interacting with changes of socio-
economic behaviour were illustrated. The policy revising the City Planning Act to limit clearly floor
area ratio for building construction within the city in relation to land use categories - commercial
areas, residential areas, industrial areas - generates the desired urban growth and urbanization.
Summary
Problems
One way of geographically understanding the evolution of cities is to think of urban future
as being a response to the present pattern of socio-economic forces. Urban system can be
conceived of as comprising two main components : the system of cities focusing on cities as points
in space and the internal structure of cities focusing on the spatial arrangement of place and
activities within those cities (Cadwallader, 1985:1). Model-building approaches to understanding
urban process and phenomena are only selective approximations of reality, in that incidental detail is
omitted in order to generalize certain fundamental relationships. Although models can be used as
tools in that they allow complex phenomena to be visualized and understood more easily , they also
entail disadvantages. In particular, despite the recent advances involving dynamics models (Clarke
and Wilson, 1983: Wilson, 1981), models can present an overly simplified view of reality which
leads to unsuccessful predictions. Most analytical modelling methods seldom incorporate the
historical context of urban development, thus failing to appreciate the role of changing patterns of
landownership, legislation, government or institutional policy (Gordon, 1981). Observations in real
behaviour of urban development such as Bangkok, both government and business sectors consider
the importance of economic growth as priority and separately from the spatial planning. The delay
and unawareness of urban legislations due to political economy result in uncontrolling urban
growth and disorderly urbanization. City Planning Act was ineffective to control specific land use
policy and speculative development, especially at the edge of the city within the rural-urban fringe
due to rapid economic growth and regulations related to City Planning are disorganized and
diverged in implementation.
RSA
System Dynamics '95 — Volume II
Many studies and teaching in the City Planning Courses also individually focus on socio-
economic planning or spatial planning. Due to this shortcomings, this paper attempts to integrate
both aspects into one approach, based on modelling concepts of classical model - the Concentric
Zone Model and advanced model: System Dynamics Model of Urban Growth.
Model Design and Reference Modes
Two models are linked and applied for spatial and socio-economic analyses for this study.
The Concentric Zone Model which was formulated by Burgess (1925), suggested that the urban
pattern could be summarized in terms of five concentric land use zones. These land use zones not
only described the pattern at a particular point in time, but also represented the successive zones of
urban expansion. The innermost zone was the central business district. This zone contained the
downtown retailing districts, plus major office building and banks. Surrounding this area was the
wholesale business district, with its associated warehouses called the zone in transition. This zone
was characterized by inner factory belt and an outer ring of deteriorating residential
neighbourhoods. The third zone was labelled the zone of independent workingmen's homes while
the fourth zone was the zone of better residences. The fifth or outermost zone was the commuter's
zone. This zone lay outside the legal boundary of the city (Cadwallader, 1985:118). This model is
applied to explain patterns of spatial interaction or movement patterns within the city. Spatial
distributions of particular variables such as land use and land value are connected to the Urban
Growth Model which was formulated based on the URBAN1 model developed by Alfred and
Graham in 1976, to explain the dynamic interactions of socio-economic variables within the urban
system. The model represents interactions between population, housing, business structure,
economic development, transportation access and land system subsystems with the policy inputs of
exercising the City Planning Act. Two key-policy parameters- floor area ratio and building code-
coverage area were tested.
Three kinds of maps were used for spatial analyses by means of Geographic Information
System- (1) spatial data from a color composite of three Spot Pla Images acquired on 7 December
1989, 10 November 1992 and 14 April 1994 were employed showing the expanding urban area of
Bangkok and spatial analyses of urbanization; (2) Aerial photo map of particular district such as
Donmuang district in 1991, scale :1:20,000 was used to observe the changes of settlement patterns,
(3) actual land use map from field survey conducted by Office of City Plan in 1986 (the lowest
economic growth rate in a cycle of eight years (1986-1993) was also used as base map to examine
the changes of particular vacant land use in response to the urban growth. A cycle of urban growth
from 1986 to 1993 in terms of interactions between economic growth (loan interest rates for
housing) and the expansion of housing was illustrated in time series as reference mode.
Policy Experiments
Policy alternatives with various regulations related to the City Planning Act were tested and
illustrated spatially the possibilities to limit urban growth and urbanization.
* Full paper will be distributed and presented at the Conference’ s session.
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