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Alonso model

  A model developed by William Alonso (1964), building on the von Thünen model of agricultural land-use patterns, to account for intra-urban variations in land values, land use, and land-use intensity in modern capitalist cities.

The model \'s key components are accessibility and its relationship to transport costs. Its simplest form assumes that all journeys from residential to non-residential areas focus on the city centre so that, assuming that households have fixed budgets, the further that a household lives from the city centre the more it will need to spend on commuting and other journeys (such as to shops) and the less it will have available to spend on land and property .

All land users benefit from increased accessibility, according to the model, and thus bid to be at or close to the city centre: among commercial and industrial users, for example, the closer they are to the city centre the nearer they are to their suppliers and customers, the lower their transport costs and the greater their profit margins (all other things being equal); then they will be prepared to pay more for such advantageous locations. In general, these users benefit more from greater accessibility than do households (with commercial users benefiting more than industrial); they can outbid residential users for city centre land, which produces a zonal distribution of land uses around the centre (as shown in the figure). Because land is more expensive close to the centre, it tends to be used more intensively (e.g. buildings are on average higher and occupy more of their site).

{img src=show_image.php?name=bkhumgeofig2.gif }

Alonso model Concentric land-use zones generated by the bid-rent curves for retailing, industrial and residential land use (Cadwallader, 1985)

The closer that a household or firm locates to the central point the higher the rent that must be paid. There is a distance-decay relationship away from the city centre in the value of locational rents. Each land use has an indifference curve which represents the relative priority given to accessibility (and high density locations) over travel costs from lower density locations. (The amount of land available increases with the square of the distance from the centre, increasing its supply relative to demand.) At the centre, accessibility has the greatest priority and travel costs the least, so rents are highest there; further out, as travel costs increase so rents fall to compensate for the greater costs of movement. According to Alonso, all individual location decision-makers have their own bid-rent curves indicating their relative priorities for rent and travel costs: the point at which each bid-rent curve touches the indifference curve identifies that individual\'s preferred location.

Alonso \'s model of a unicentric city is readily modified to accommodate more than one centre (several shopping centres, for example) and differential patterns of accessibility (such as fast and slow routes to and from the centres). Its hypotheses of declining land rents, values and use intensities away from the defined centres have been largely validated in a substantial number of empirical studies although, as a classic study of Boston illustrated (Firey, 1947), such a model cannot account for the high prices that some people will pay for locations on the basis of criteria like \'sentiment and symbolism\'.

Alonso \'s model provides an economic rationale for the zonal model of urban land uses identified by American sociologists in the 1920s. It also shows why those with higher incomes will tend to favour suburban locations within the residential portion of the city, leaving the inner city to be occupied by lower-income groups at higher densities (thereby maximizing the returns on expensive land): this implies that the higher-income groups have different indifference curves from the less well-off, although gentrification processes emerge where the richer residents prefer accessibility to the lower densities of the suburbs. (RJJ)

References Alonso, W. 1964: Location and land use: toward a general theory of land rent. Cambridge, MA: Harvard University Press. Cadwallader, M. 1985: Analytical urban geography: spatial patterns and theories. Englewood Cliffs, NJ: Prentice-Hall. Firey, W. 1947: Land use in central Boston. Cambridge, MA: Harvard University Press.



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Other Terms : activism and the academy | revealed preference analysis | accessibility
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