DEVELOPMENT OF A SIMULATION MODEL TO STUDY THE IMPACTS OF RAPID URBAN GROWTH ON THE TRANSPORTATION SECTOR--THE CASE OF CHARLOTTE, NORTH CAROLINA

To successfully plan for the development of a region, it is necessary to understand the possible causal relationships, feedbacks, and interactions between the different sectors of the region, including the transportation sector. In this paper a conceptual framework is presented along with a mathematical model for studying the problems of urbanized regions using system dynamics and simulation techniques developed by J.W. Forrester. The conceptual view of the approach is presented by causal submodels of the eight main sectors of the economy: population, housing, business, heavy manufacturing, light manufacturing, government, agriculture, and transportation. The mathematical model, which is represented by 96 differential difference equations, was used to evaluate the impacts of three urban policies on the transportation sector: (a) heavy manufacturing, (b) light manufacturing, and (c) downtown development. Policy c provided the least negative impacts on the transportation sector; that is, with a level of service of 0.6 for freeways and 0.4 for primary arterials, and even more significant, only 0.3 of the urban land fraction occupied by 1990. The strength of the proposed modeling technique presented here is not so much in the absolute values of the output of the three investment strategies, but, rather, in the use of the model as a planning tool to understand and study the direction in which the economy is likely to go and especially the impacts of a given urbanization policy on the transportation sector.