CA City: Simulating Urban Growth through the Application of Cellular Automata

It is estimated that 3.5 billion people currently live in cities, which equates to more than 50% of the total population (UN, 2010). These cities vary in size from 500,000 to over 10 million inhabitants (termed mega-cities). The number of cities, in particularly mega-cities, are set to significantly increase by 2050. However, this rapid urban population growth is taking place at differing speeds and spatial scales across the globe. Developing countries are experiencing a much higher level of urbanisation than developed countries. For example, by 2050, it is expected that Europe will be 84% urbanised (compared to 82% in 2010), whilst Asia and Africa will be 65% and 62% urbanised by 2050, respectively, compared to 40% in 2010 (UN, 2010). Such rapid urbanisation, normally unplanned and spontaneous, brings its own set of problems, in both the social and physical environment. These include spatial segregation of the rich and poor, shortages in urban housing and basic services, and the production of vast volumes of waste and harmful synthetic materials (Pacione, 2005), as well as urban poverty. Psychologically, urbanisation can engender feelings of loneliness, self-centeredness, loss of a sense of community, and increasing crime rates (Knox, 1994). To mitigate for these types of problems as well as to manage and plan future urban growth, a range of modelling techniques has been applied. The development of urban theory and modelling has a long history, e.g. Industrial Location Theory (Weber, 1909), Central Place Theory (Christaller, 1933), the Concentric Zone Model (Burgess, 1925), the Sector Model (Hoyt, 1939) and the Multiple Nuclei Model (Harris and Ullman, 1945). These classical theories and models have formed the foundation for studying urban structure and growth, but they have been criticised for being overly simplistic, unrealistic in their assumptions, and not applicable to the structure of today’s cities (Chapin and Kaiser, 1979; Briassoulis, 2000; Batty, 1994, 1996). Another major criticism levelled at these models is their static nature. They are unable to explain the spontaneous growth that has taken place in modern cities under a non-equilibrium status, which has evolved diversely from highly dispersed edge cities to