# System of central places

Schematic representation of the central locations with connecting axes in a homogeneous space

The system of central places is a theory of spatial planning that divides places into different classes of meaning according to the role they play as a central place ( main place ) for the surrounding area .

## History and content of the theory

The theory of a system of central locations was developed in the 1930s by the German geographer Walter Christaller (1893–1969). In his model , a structure of central locations on different hierarchical levels develops in ideal-typical, homogeneous spaces. The central locations of higher hierarchical levels (e.g. larger cities ) have equipment features that the central locations of lower hierarchical levels lack (e.g. certain administrative and service functions). A central location thus has an excess of significance for the supplementary area surrounding it . Christaller determined the centrality or the excess of meaning of a place as the relationship between the services that are provided as a whole (for the place and its supplementary area) and the services that are only required for the residents of the central place itself. The difference between the two values ​​is called the excess of significance. The higher the centrality of a place, the greater the number of services per resident.

## Christaller system

Christaller first developed the concept of the system of central places in his main work, the 1933 book The Central Places in Southern Germany . He showed that a region is supplied with higher quality services and goods from centers. In the structure originally organized by Christaller according to the supply principle (K = 3), ten hierarchical levels were distinguished (from “auxiliary central location” to “Reich capital”). Christaller tested his theory in practice using the number and distribution of the telephone connections available at the time:

${\ displaystyle ZI = nTel-N \ times Middle}$
${\ displaystyle ZI}$ ... centrality index
${\ displaystyle nTel}$ ... number of telephone connections
${\ displaystyle N}$ … Population
${\ displaystyle Middle}$ … Mean value of the number of telephone connections per inhabitant in the supplementary area

Christaller used deductively determined premises as a basis:

• Extensive homogeneity of the rooms or sub-rooms:
• Production and demand are largely the same in an unlimited area
• Production factors and the population are almost evenly distributed in space
• Income, purchasing power and needs of all individuals are the same
• Roughly uniform transport network in all directions
• The transport costs are directly proportional to the distance
• Orientation towards economic ideals:
• Providers strive for the greatest possible profit
• Customers strive for the greatest possible benefit (" homo oeconomicus ")
• The same information base (omniscient) for all market participants
• No spatial specialization of the providers
• Every central good has two ranges:
• Inner range: A turnover threshold is understood to be the market-related threshold below which a location can no longer deliver goods, i.e. demand and sales volume are too low to achieve sufficient profit. This threshold represents a lower limit for the supply side.
• External range: The range of a central good is understood to be the upper limit of its market area. It corresponds to the distance outside of which the central location can no longer sell the product (consumers are not prepared to travel even longer). This threshold works on the demand side.

In order for the market of supply and demand to function, the internal range must be smaller than the external.

Under the theoretical assumption that the traffic connections are equally good in all directions, the upper and lower range are delimited in a circle with the central location in the geometric center.

Arrangement of central locations in the room related to a single central good

Since the outer ranges of neighboring locations on the one hand will not overlap (parts of the supplementary areas would otherwise be supplied twice) and on the other hand, the central locations should have equal and as small a distance as possible from one another (areas that are not covered), the central locations are arranged in a regular triangular grid with hexagonal supplementary areas around each location, because this is the only way to supply an area seamlessly and economically as efficiently as possible.

## Supply and market principle (K-3 system)

K-3 system

Under these idealized conditions, Christaller initially developed a tiered system of supply centers in regions based on the market principle . Market principle : k = 3, because 1 + 6 * 1/3 = 3. The surrounding six smaller centers sit here at the corners of a hexagon and each cover a third of their need for higher-value goods or services in the three surrounding higher centers.

The supply of central goods is as close as possible to the locations to be supplied (triangular grid). A central location of higher order supplies itself and two neighboring locations of lower order (hence k = 3).

In the regional planning of the Federal Republic of Germany, this structure was transferred to planning, whereby entire communities are classified in a hierarchical and functionally structured, normative order model, e.g. B. in the form of sub- centers , medium-sized centers and regional centers . They have ascending catchment areas (supply or interlinked areas or supplementary areas), an increasing range of goods and services and an increasingly dense infrastructure :

Sub-centers (basic or small centers)
serve to cover the "basic supply" (especially short-term or daily needs), DAILY
Middle centers
serve to cover the "basic supply" and the medium-term or "high" demand, PERIODIC
Regional centers
serve to cover the "basic supply", the long-term, d. H. “Upscale” as well as “specialized, higher” needs. EPISODIC

However, it remains largely unclear which central location facilities with which central location equipment features are to be assigned to the respective supply or requirement level. It also remains unclear from which equipment density a minimum supply is guaranteed or at risk. The definition of generally applicable, binding equipment catalogs and standards for the minimum supply of a center has so far failed. To a limited extent, the actual importance of a center can be derived empirically from retail centrality. This centrality index does not allow any direct conclusions to be drawn about the other aspects of centrality (e.g. the centrality of transport, cultural, educational and service facilities).

An upper center with its middle and lower services and goods is also a middle and sub-center, a middle center is also a sub-center. However, the catchment area is shrinking according to demand. The high-quality goods and services are correspondingly less in demand.

For example, each sub-center should be assigned a primary school. The catchment area of ​​the elementary school is local (close area as a supply or interconnected area). A grammar school, which is less in demand, corresponds to the central local functions of a medium-sized center and usually has a correspondingly larger catchment area (medium-sized area with several sub-centers). A university corresponds to the central local functions of a regional center, is in even less demand than a grammar school and has an even larger catchment area (upper area as a supply or interlinked area or supplementary area), which ideally extends over the area of ​​several lower and middle centers.

That this example does not match the real demand behavior is shown by the fact that people with higher education entrance qualifications usually do not choose their university according to the system of central locations, but according to other, typically personal, selection criteria. It can also be seen in other central location institutions that the real demand behavior does not correspond to the system of central locations. For this reason, the system of central locations in spatial sciences and in the area of ​​spatial planning law is increasingly being called into question.

Due to the ambiguity in the allocation of mandatory equipment features, the regional planning regulations, with which a system of central locations was fixed in the regional planning plans of the federal states and regions, have often remained indefinite. However, since the Spatial Planning Act requires a specificity or determinability (standard clarity) for the planning municipalities (norm addressees) for binding objectives of spatial planning (Section 3 (1) No. 2 Spatial Planning Act), the corresponding provisions only make one principle of spatial planning legally binding (Section 3 Para. 1 No. 3 Regional Planning Act), which can be overcome by the municipality in the context of its structural planning considerations (planning fairs).

## Traffic principle (K-4 system)

K-4 system

The necessity of the most economical transport connection possible - as an alternative structuring approach - is optimized in the K-4 system . Here the smaller places are on the sides of the imaginary hexagons. So they can be connected in a straight line with the larger centers ( see figure above ). This saves money on road construction and time on the road.

The catchment area here corresponds to half of six lower centers ⇒ 6 * 1/2 + 1 = 4.

## Management principle (K-7 system)

K-7 system

In the administration there is a need to define clear responsibilities. The K-3 and K-4 systems are useless here, since smaller towns would have to be divided or belong to several higher levels (e.g. rural districts). So here an assignment of the surrounding places to a center is realized with the K-7 system . The lower places are entirely in a hexagon, in the center of which the higher value central place is located ( see figure above ).

Here the area of ​​action is extended to six surrounding complete lower centers and one's own lower center ⇒6 + 1 = 7

## application

The conception of the central locations has also found its way into the German Spatial Planning Act (ROG), which in the principles of spatial planning requires, among other things, the spatial concentration of settlement activities on a system of efficient central places within the framework of a decentralized settlement structure (Section 2 (2) No. 2 ROG). The states fill out the framework law with the establishment of state development programs and state development plans with which they identify, develop and promote their area in accordance with this basic concept.

In many cases, when designing their system of efficient central locations, the federal states have classified their municipalities in upper, middle and sub-centers with corresponding supply or interrelated areas (e.g. near, middle and upper areas), which have different minimum standards of care and equipment should meet. However, the low density, clarity of information and binding nature of the regulations issued for this purpose have often impaired the implementation of the system of efficient central locations from spatial planning into urban development planning of the municipalities.

Due to new developments ( suburbanization , teleworking , just-in-time production , state subsidies for goods transport, mobility, lifestyles and consumer habits, etc.), the current settlement development is also moving more and more away from Christaller's model ideas. The system of central locations in spatial planning is therefore increasingly losing its application relevance and thus its importance. The empirical verification of the equipment of places with central goods is becoming increasingly difficult.

One example of the increasing decoupling of supplier locations from cities at the corresponding hierarchical level are the large furniture retailers ( e.g. IKEA ). Furniture as a range of goods with an episodic demand no longer necessarily has to be offered in a large town or town, but is often found on the proverbial “ green field ”. The priority of the providers has clearly shifted in favor of accessibility for customer and supplier traffic: preference is given to large, well-developed commercial locations in the immediate vicinity of a motorway . Empirical studies have shown that furniture customers accept locations of up to an hour to travel by car.

Another vivid example of the problem of the system of central locations is the Ruhr area . Its development processes and settlement structures cannot be explained with Christaller's model, because the ideal-typical space and the typical market conditions that Christaller presupposes as basic assumptions for the application of his theory were not present here. As is well known in the Ruhr has an industrialization process which was essential parts focused on natural resources , the settlements and centers structures of the Ruhr industrial use and to create industrially required operating and infrastructure, specifically marked. Christaller did not research or explain the market forces and local conditions at work in such a process.

The use of a conventional system of central locations in spatial planning is a considerable problem for settlement and center structures like those that characterize the Ruhr area as a metropolitan area, because the system of central locations that was originally not intended for atypical areas is constantly linked to the market and and site conditions come into conflict. In addition, due to the low density, clarity of information and the binding nature of the regional planning regulations of the federal states developed for this purpose, the system of central locations often cannot affect the municipal land-use planning.