Central Place Theory
From Freepedia
Central Place Theory is a geographical theory that seeks to explain the size and spacing of human settlements. It rests on the notion that centralisation is a natural principle of order and that human settlements follow it. Created by Walter Christaller, the theory suggests that there are laws determining the number, size and distribution of towns. He was interested only in their functions as markets, thus excluding specialist towns such as mining settlements. He argued that the significance of a town cannot be measured by population alone.
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Building the theory
To develop the theory, Christaller made the following simplifying assumptions:
- an isotropic (all flat), limitless surface
- an evenly distributed population
- evenly distributed resources
- all consumers have a similar purchasing power
- no provider of goods or services is able to earn excess profit
Therefore the trade areas of these central places who provide a particular good or service must all be of equal size
- there is only one type of transport and this would be equally easy in all directions
The theory then relied on two concepts: threshold and range.
- Threshold is the minimum market (population or income) needed to bring about the selling particular good or service.
- Range is the maximum distance consumers are prepared to travel to acquire goods - at some point from the centre cost or inconvenience will outweigh the need for the good.
The result of these consumer preferences is that a system of centers of various sizes will emerge over space. Each center will supply particular types of goods forming levels of hierarchy. In the functional Hierarchies, generalizations can be made regarding the spacing, size and function of settlements.
1.The larger the settlements are in size, the fewer in number they will be, ie there are many small villages, but relatively few large cities
2.The larger the settlements grow in size, the greater the distance between them, ie villages are usually found close together, while cities are spaced much further apart.
3.As a settlement increases in size, the range and number of its functions will increase
4.As a settlement increases in size, the number of higher-order services will also increase, ie a greater degree of specialisation occurs in the services.
Predictions of the theory
From this he deduced that settlements would tend to form in a triangular lattice, this being the most efficient pattern for travel between settlements (derived from stacking theory).
In the orderly arrangement of a urban hierarchy, 7 different principal orders have been identified by Christaller, providing different groups of goods and services. Settlement are regularly spaced- equidistant spacing between same order centers, with larger centers farther apart than smaller centers. Settlements have hexagonal market areas, and are most efficient in number and functions.
K=3 Marketing Principle
According to the marketing principle k=3, the market area of a higher-order place includes a third of the market area of each of the following siz neighbouring lower-order places. For every three same-order centers, there would be a larger, more specialized urban center. This center in turn would be at equal distance from other centers of the same order and with the same level of specialization as itself. Such as center would also have a larger hexagonal hinterlands.
However, although in this K=3 marketing network the distance travelled is minimized, the transport network is not the most efficient, because the important transport links between the larger places do not pass through intermediate places.
K=4 Transport Principle
According to K=4 transport princple, the market area of a higher-order place includes a half of the market area of each of the six neighbouring lower-order places. This generates a hierarchy of central places which results in the most efficient transport network. There are maximum central places possible located on the main transport routes connecting the higher-order centers.
K=7 Administrative Principle
According to k=7 administrative principle (or political-social principle), settlements are nested according to sevens. The tributary area of a higher-order central place includes the whole of the tributary area of each of the six neighbouring lower-order central places. Since tributary area cannot be spilt administratively, the must be allocated exclusively to a single higher-order place. Efficient administration is the control principle in this hierarchy.
Evaluation
The validity of the central place theory may vary with local factors, such as climate, relief, history of development, technological improvement and personal preference of consumers and suppliers.
Economic status of consumers in an area is also important. Consumers of higher economic status tend to be more mobile and therefore bypass centers providing only lower order goods. The application of central place theory must be tempered by an awareness of such factors when planning shopping center space location.
Purchasing power and density affect the spacing of centers and hierarchical arrangements. Sufficient densitites will allow, for example, a grocery store, a lower order function, to survive in an isolated location.
Factors shaping the extent of market areas:
- Land use: industrial areas can provide little in the way of a consuming population
- Poor accessibility: this can limit the extent of a center's market area
- Competition: this limits the extent of market areas in all directions
- Technology: high mobility afforded by the automobile allows overlapping of market areas
Market area studies provide another technique for using central place theory as a retail location planning tool. The hierarchy of shopping centers has been widely used in the planning of "new towns". In this new town, the hierarchy of business centers is evident. One main shopping center provides mostly durable goods (higher order); district and local shopping centers supply, increasingly, convenience (lower order) goods. These centers provided for in the new town plan are not free from outside competition. The impacts of surrounding existing centers on the new town centers cannot be ignored.
