Chris Webster

Simulation of Land Development through the Integration of Cellular Automata and Multicriteria Evaluation

Cellular automata (CA) simulation has become a popular method of exploring the behaviour of all kinds of self-organising systems. The city may clearly be viewed as such a system but one with a particularly complex set of transition rules. Many natural processes such as the spread of fire or vegetation can be modelled by a simple set of local rules. Insofar as the development of a piece of land depends on the neighbourhood situation as well as on the characteristics of a site, urban evolution can be treated in much the same way, with transition rules translating the evaluation of the location into a land conversion outcome. If this modelling paradigm is to be used to gain insight into real-world urban development processes, there is a need to discover ways of capturing the richness of land conversion behaviour in the simplifying mechanisms of CA. Our paper contributes to this research agenda by integrating multicriteria evaluation (MCE) into a CA simulation in order to define nondeterministic, multidimensional, and multilevel transition rules. An analytical hierarchy process is used to implement MCE-derived transition rules. The integrated MCE – CA model may be used in a gaming mode to explore how urban form evolves under different development regimes caricatured by the set of multicriteria weights. We use it to test loosely hypotheses about the nature of the regimes that have governed the expansion of a fast-growing southern Chinese city.

Property rights and the public realm: gates, green belts, and Gemeinschaft

Discussions about gated communities, shopping malls, and industrial parks—proprietary developments produced by entrepreneurs—frequently espouse overly simplistic notions of private and public realms, viewing the encroachment of the latter by the former as a threat. In this essay I develop the thesis that, in reality, cities naturally fragment into many small publics, each of which may be thought of as a collective consumption club. The club realm may, therefore, be a more useful—and theoretically more powerful—idea than the public realm. I argue that proprietary communities are a particular case of urban consumption club—one in which legal property rights over neighbourhood public goods are assigned by property-market institutions. In other respects, the club realms that they create are not dissimilar from club realms created by other urban governance institutions. Government, the markets, and voluntary community action can all effectively assign property rights over shared neighbourhood goods, and in so doing create a set of included ‘members’ and a set of excluded ‘nonmembers’. In contextualising the discussions of gated communities in this way, I draw connections between three interrelated concepts: public goods, the public domain, and the public realm.

Simulating artificial cities in a GIS environment: Urban growth under alternative regulation regimes

This paper reports on an attempt to combine neo-classical urban economic theory with complex systems methods. The innovative feature of our model from the point of view of conventional economic theory lies in its explicit treatment of spatial relationships and time sequence. From the perspective of raster or cellular GIS models of urban processes, the work is innovative in that it replaces the more usual heuristic cell-transition rules with micro-economic theory. The mix of modelling paradigms is not unproblematic, however, and we discuss the challenges encountered at this research frontier. These notwithstanding, our hybrid model has the potential to be used as a GIS-based laboratory for exploring micro-economic propositions, particularly those relating to urban processes that are path dependent. The version of the model reported simulates spatially equilibriated path dependent futures of a city governed by local development decisions that are at partial equilibria in the neo-classical sense. Two simulations are described which permit visual and economic exploration of (a) an explicitly spatial version of the economic theory of externalities and (b) a new theory of densification. The dual paradigm (Cellular Automata-neo-classical economics) leads to an interesting class of simulations in terms of stability. Economically our simulated cities become increasingly efficient, in terms of private and social product. The long-run economic equilibrium is achieved by many individually efficient negotiations based only on local information. There is no parallel long-run spatial equilibrium however. The spatial configuration of land uses is constantly shifting as a result of randomness in the land use bidding process. The spatial instability is, however, limited by the self-organised drive for greater overall economic efficiency. In economic terms, the models spatial instability represents random re-allocation of land-use within a set of Pareto-efficient spatial configurations - an intriguing result that we intend to follow up in future work.

Homeowners Associations, Collective Action and the Costs of Private Governance

This paper examines collective action problems in privately managed neighbourhoods and considers government and market reponses to these. Taiwans experience of Home Owners Associations (HOAs) is used to show that entrepreneurs have a strong incentive to deliver private governance capacity and are apparently more effective in doing so than either government (by coercion) or residents (by voluntary association). However, government needs to reduce certain collective action costs by providing appropriate enabling legislation. While the market can deliver private democratic government, it cannot do so in a way that avoids many of the costly features of public government. Within HOAs, problems of information asymmetry and opportunism, collective action and rent-seeking all persist. The paper concludes that much of the efficiency of contractual democratic neighbourhoods comes through the privatisation of bureaucracy—handing over civic goods and services supply and management to highly competitive and innovative property companies—rather than through HOA governance structures per se. The latter are characterised by many of the same problems that weigh down conventional municipal government.

Public choice, pigouvian and coasian planning theory

With urban planning policy in transition in many parts of the world, the need to understand the theoretical bases for planning and to ground discussion about policy innovations on theory is as important as ever. This essay reviews the relevance of three economic paradigms to the theory of development control. It is written as a technical review with the purpose of explaining, contrasting and contextualising the contributions of these paradigms. Much has been written about the Pigouvian case for regulative planning. The Coasian literature is strong especially in the US but is not so well known elsewhere; and little has been written that draws together the diverse perspectives offered by the public choice school. This essay has been written particularly for academic planners and urban social scientists in the UK, and in other European and Commonwealth countries who are not familiar with the technical arguments underlying the Coase vs Pigou zoning debate. It is also an essay on the public choice theory of planning since it contextualises Coasian planning theory within that wider critique of welfare economics. Among other points, it argues that the relevance of Coasian planning theory is not by any means restricted to US-style zoning, nor is it purely a debate about deregulation. Coasian and other public choice perspectives generate a rich source of theoretical and empirical propositions which should be tested and developed, particularly as frameworks for comparative analysis of planning constitutions and policies. In this spirit, the essay concludes with elements of a research agenda.

The Donald Robertson Memorial Prizewinner 2003: The Nature of the Neighbourhood

This paper considers the order that emerges in cities as individuals exchange and pool rights over resources in pursuit of individual and mutual gain. In his 1937 article The nature of the firm, Ronald Coase explained the existence and size of firms in terms of transaction costs. Neighbourhoods are important units of consumption and production and can, like firms, be explained by transaction costs. A theory of the neighbourhood is developed based on transaction costs, property rights and related ideas from the new institutional economics. A neighbourhood is defined as a nexus of contracts and four rules that govern neighbourhood evolution are specified. Normative aspects of the theory are illustrated by examining the organisational order in neighbourhoods, in particular, the pattern of residual claimants in the contracts that underpin neighbourhood dynamics.

GIS and the scientific inputs to urban planning. Part 1: description

Urban planning is one of many fields in which the advantages of GIS seem to be broadly accepted in general but not always in the particular; there are still many hazy ideas about the benefits of the technology and little systematic guidance on the matter. This paper is the first of a two-part review defining the scope of the contribution of GIS in planning analysis. The usefulness of GIS as a tool for building planning support systems, it is argued, is best assessed with reference to the nature of the scientific input required at the various stages of decisionmaking. Characterising planning by its scientific inputs, defined in terms of procedural and substantive planning theory, the author attempts to make definitive statements about the potential contribution of GIS irrespective of specific current technologies or the existence of tried applications. The technologys limitations as a planning aid are also highlighted, and tasks for which GIS offers little or no substantial advantages are identified. In this respect this paper should provide a useful guide to the GIS agendas of planning practitioners and researchers as well as being a pedagogic device. In this first paper, the role of GIS in descriptive analysis is discussed. In the second paper the focus shifts to predictive and prescriptive analysis, and it concludes with some general principles and pointers to the future of GIS in planning.

Social Groups and Housing Differentiation in China's Urban Villages: An Institutional Interpretation

Possessing different land rights and distinct landscapes, and separated from the rest of the city by invisible institutional boundaries, Chinas urban villages are unusual enclaves for landless farmers, rural migrants and other urban hukou (citizenship rights) holders in a period of rapid urbanization. Although urban villages are well known for their disorder and unruliness, they provide temporary livelihood for indigenous villagers and inexpensive shelter for migrants and other urban residents. Urban villages are typically perceived as homogeneous low-income neighbourhoods characterized by low quality and high density housing. In fact, housing differentiation has emerged in urban villages among residents who possess different quantities and types of capital, rights/entitlements, skills and other assets. This paper aims to understand the social groups and the housing differentiation among them in the Chinese urban villages from an institutional perspective. It is based on a large-scale household survey in 11 urban villages in six Chinese cities. Empirical data show evidence of significant housing differentiation within these enclaves: indigenous villagers have become a petty rentier class; rural migrants pay the highest rents while enduring the lowest housing conditions; and housing conditions for urban hukou holders lie between those of the other two groups. Regression analysis suggests that urban villages share similar dynamics of housing differentiation as wider urban spaces, i.e. the combination of strong institutional constraints and emerging market influences leads to housing differentiation and inequality. Residents in urban villages are also highly mobile. The inflows and outflows of population form an important part of the urban socio-spatial restructuring process.

Coase, spatial pricing and self-organising cities.

Modern computational techniques offer new horizons for urban economics in the form of agent-based simulation frameworks. This paper reports on a cellular automata (CA) simulation in which urban land transforms on the basis of locally optimal bargaining between developers and local communities (local governments). Because CA is an explicitly spatial modelling methodology, the space-time-specific paths to global equilibrium can be observed. Because it is an atomistic methodology (cells represent decision units), it is suitable for articulating microeconomic theories of urban processes including planning. We present a space-time-specific simulation of cities evolving under two alternative planning regimes. In one, the community has property rights and uses planning conditions, planning gain, impact fees and so on to ensure that each development occurs at a socially optimal density. This is a theoretically simplified rendition of the British development control system-simplified in the sense of acting from a position of perfect knowledge and having a single objective of optimising locational externalities. In the other simulation, developers have the right to develop but the community is allowed to make (rather than receive) compensatory payments in order to achieve socially optimal land-use patterns and densities. Decision-making in both systems is local and socially efficient. However, case-by-case ad hoc development control with compensatory exactions has the effect of steering development to the least-polluting locations. Although socially optimal densities can occur under alternative control regimes (as the second simulation demonstrates), the stylised British development control process acts like a decentralised locational pricing system and, by definition, yields a superior land-use pattern than any other style of planning system. At one level, our model articulates the Coasian invariance theorem-the same partial equilibrium outcome can be achieved whichever way the property rights (over land development) fall. At another level, the results demonstrate that in a spatial resource allocation problem such as land-use planning, global equilibrium is not independent of property rights. The total social product in the urban land economy is greater when the community holds rights over development.

Land dispossession and enrichment in china's suburban villages

This paper takes a fresh look at the land dispossession that is central to Chinese urbanisation. It documents in detail the property rights changes that occur when village land is taken by a municipal government and analyses the value of those rights by looking at compensation accounts for a case study village in the city of Xiamen in Fujian Province. The purpose of the paper is to show the complexity of the property rights dynamics during land expropriation and the results in terms of villager income. The paper also shows that, in Xiamen, the local state has made a series of concessions such that displaced villagers now receive a compensation package that not only includes compensation for lost agricultural land, production and homes but also a share of the urban land value uplift created by the infrastructure investments of the municipal state.