Central Place Theory

Central Place Theory is a geographical theory that seeks to explain the size and spacing of human settlements. It rests on the notion that centralization 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 population alone couldn’t measure the significance of a town.

Building the theory

To develop the theory, Christaller made the following simplifying assumptions:

an isotropic (all flat), homogeneous, unbounded limitless surface
an evenly distributed population
evenly distributed resources
all consumers have a similar purchasing power and demand for goods and services
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
transport cost is proportional to distance travelled ie, the longer the distance travelled, the higher the transport cost

The theory then relied on two concepts: threshold and range.

Threshold is the minimum market (population or income) needed to bring about the selling of a particular good or service.
Range is the maximum distance consumers are prepared to travel to acquire goods - at some point from the 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. 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.

The larger the settlements are in size, the fewer in number they will be, i.e. there are many small villages, but relatively few large cities.
The larger the settlements grow in size, the greater the distance between them, i.e. villages are usually found close together, while cities are spaced much further apart.
As a settlement increases in size, the range and number of its functions will increase .
As a settlement increases in size, the number of higher-order services will also increase, i.e. a greater degree of specialisation occurs in the services.

The higher the order of the goods and services (more durable, valuable and variable), the larger the range of the goods and services, the longer the distance people are willing to travel to acquire them

Examples for low order goods and services are: newspaper stalls, groceries, bakeries and post offices. They are supported by a relatively smaller threshold population and demand. Examples for high order goods and services are: jewellery, large shopping arcades and malls. They are supoorted by a much larger threshold population and demand.

Predictions of the theory

From this he deduced that settlements would tend to form in a triangular/hexagonal lattice, this being the most efficient pattern for travel between settlements (derived from stacking theory).

In the orderly arrangement of an urban hierarchy, 7 different principal orders of settlement 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.

The different layouts predicted by Christaller have K-values which show how much the Sphere of Influence of the central places takes in - the central place itself counts as 1 and each portion of a satellite counts as its portion:

= 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 size neighbouring lower-order places and each is located at the corner of a hexagon around the high-order settlement. Each high-order settlement gets 1/3 of each satellite settlement, thus K=1+6*1/3=3.

However, although in this K=3 marketing network the distance traveled 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, as they are located on the edges of hexagons around the high-order settlements. 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 market areas of the smaller settlements are completely enclosed within the market area of the larger settlement. Since tributary areas cannot be spilt administratively, they 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, topography, 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.

Examples

The Polders of Holland provide an isotropic plane on which settlements have developed and in certain areas 6 small towns can be seen surrounding a larger town. The Fens of East Anglia in the UK laos provide a large expanse of flat land with no natural barriers to settlement development. Cambridge is a good example of a Central Place, although it is surrounded by 7, rather than 6, settlements. Each is 10-15 miles from Cambridge and each lies on a major road lading out of Cambridge:

Ely - A10 north
Newmarket - A1303 (bypassed by A14/A11) northeast
Haverhill - A1307 southeast
Saffron Walden - A1301 south
Royston - A10 southwest
St Neots - A428 west
St Ives - A14 northwest

As all of the satellite settlements are on transport links, this is a good example of a K=4 CPT model (although in this case it is K=4.5)

Criticism

The Central Place Theory has been criticized for being static; it does not incorporate the temporal aspect in the development of central places. Furthermore, the theory holds up well when it comes to agricultural areas, but not industrial or postindustrial areas due to their diversified nature of various services etc.

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