Browsing by Author "Nurmio, Kimmo"

The meaning of city center as a market place has been decreasing due to the changes in retail structure. This is expressed most visibly in the growth of retail units and in the changes of location preferences of retail companies, as retail is increasingly locating into the growing retail agglomerations outside existing city centers. At worst, this development endangers the vitality of city centers and can have a negative impact on retail accessibility. For a long time the geography of retail was congruent with urban planning, but as a consequence of the changes in society, like the growing automobile dependence, the location preferences of retail began to diverge from the principles of urban planning. This trend of retail decentralization was seen to have significant impacts on people, environment and urban structure. The regulation of retail structure is nowadays an important part of urban and regional planning. It aims to secure the development of a balanced and sustainable retail network and urban structure as well as to assess and to control the impacts produced by the changes in the retail network. Retail network planning process aims to meet these goals and to fulfill the requirements set in the legislation. This study partly tries to answer to this challenge by developing a method, with which the impacts caused by significant changes in the retail network can be assessed. The objective of this research was to study the suitability of a retail gravity model on retail network planning and impact assessment. Gravity models are based on the theories of consumer spatial behavior, traditional quantitative geography and spatial interaction. The objective of the study was approached with a defined and empirically calibrated Huff model by evaluating its feasibility to assess the impacts of new retail development on existing city centers and whether the new development is regional by nature. The results of the study show that a retail gravity model is an applicable method for retail network planning and impact assessment, especially, if the model is calibrated with an empirical data about consumer shopping patterns. The catchment areas created by the model can be interpreted cartographically and used to generate numerical estimations of potential impacts on city centers. Thus, the results of the model provide perspectives both on the intensity and on the regional distribution of the impacts. With the help of the Huff model, different scenarios can also be created to support decision making. This study enhanced the understanding that consumer behavior is a complicated process, and that only part of it can be predicted with an aggregate gravity model, and hence, the results of the model must always be considered with a certain uncertainty. However, the method applied in this study, gives a good starting point for a proper interpretation, because when the model significance is known, a correct weight can be given to the results. Both the method applied in this study and the results can also be improved many ways to reduce the fluctuations and uncertainties in the results. Model parameters can be estimated with a method that minimizes the influence of the possibly random observations in the empirical data. The quality of the retail data reflecting the attraction of shopping facilities can also be improved and the accessibility measure used in the model can be developed to better meet the real travel behavior of a modern consumer. The suitability of modeling to the practice of impact assessment is, however, a challenge and a research agenda already in itself. Use of advanced methods is mostly a matter of resources and expertise, and therefore models must be transparent and easy to use, so that the assumptions and generalizations are visibly highlighted.