UNIT 1:“INTERNAL STRUCTURE OF URBAN

AREAS, DENSITY PATTERN, LANDUSE CLASSIFICATION &

CODING”PLANNING TECHNIQUES

B A S I C T E R M I N O LO GY

“INTERNAL STRUCTURES OF URBAN AREAS”

THE ELEMENTS OF STRUCTURE

Assume the spatial separation of all people and all the facilities that they need in order to live in both the biological and cultural world.

The sum of all the distances between each person and each kind of facility is total distance.

The objective is to overcome the total distance and in working towards this objective there are only two means available:

a) People can be transported to facilities

b) Facilities can be distributed to people Each method applied in the extreme produces a distinctive

kind of city. In figure a, the function of transportation is to overcome total

distance between people and facilities. In figure b, transportation has no function, total distance being

overcome by means of distribution.

Actually, neither transportation nor distribution can do the whole job, because not all people are mobile and not all facilities can be distributed.

People may be place bound because of their age (young and old) or because of their social role (as women with young children).

Some facilities can’t be distributed because they are underpinned by natural resources or because, to exist at all, they must exist at a physical or economic size which prevents indefinite multiplication.

These constraints require the use of both transportation and distribution to overcome total distance between people and facilities.

Part of the distance must be overcome by means of local facilities. The remaining or residual distance must be overcome by the

means of transportation system. Accordingly, we combine figures a & b to give a true picture of

urban structure. In this brief analysis we have identified the major functional parts

of urban structure and given them a meaning in relation to single object.

The major parts are distributed facility, undistributed facility and transportation element.

In overcoming distance the first and the third have complementary roles:

More distributed facilities means less residual distance and less need for transportation capacity;

Fewer distributed means more residual distance and greater need for transportation capacity;

Practical limits to both concentration and distribution are set by place bound people and place bound facilities.

Figure c, shows the anatomy of the human settlements conceived as a system of relating facilities to people.

It also represents the fundamental elements in any plans for the settlement.

Certain facilities can be distributed throughout the area in close physical proximity to their users.

Other facilities can be distributed only in the sense of being made possible through the transportation system.

URBAN STRUCTURE AND URBAN FORM

Our first objective was to overcome total distance between people and facilities.

A second objective related to the first, is to reduce residual distance that is, the distance remaining between people and facilities after some facilities have been localized.

Residual distance can be reduced by adjustments in the spatial form of the community.

Form is used here to mean the way the structural components just described is arranged on the ground the pattern they make.

The effects of this arrangement on, residual distance are depicted in figure c, d, f.

The obvious effect of the arrangement in figure c is much movement back and forth between people and undistributed facilities.

Consolidate these facilities at one point and the distance to be covered will reduce figure d.

It will decrease even further if the consolidated facilities are put at the centre of the population figure f.

The pursuit of the objective is to reduce residual distance and it requires that one activity centre in the urban field be privileged with respect to size and location.

This fact gives functional meaning to the core or metropolis and to the radial shape of the transportation system serving it.

THE HIERARCHICAL ASPECT OF STRUCTURE

Limits to both concentration and dispersion are set by immobile persons and by facilities which cannot be distributed.

But not all persons are equally mobile, and not all facilities are fixed or concentrated in the same degree.

Mobility differs according to age, sex and income etc., whereas distribution is a matter of economic plant size or of the spatial scatter of natural resources.

These facts explain the hierarchical tendency of the urban structure: People must travel different distances to facilities and the facilities themselves have different service radii.

Also, they account in part for the existence of central places of several sizes and the corresponding differentiation of the highways which serve them into major and minor arterial and local roads.

As there is more than one level of community, planning must be carried out at more than one level.

THE WHOLE AND THE PART

The bringing of people and facilities together creates three urban structural elements.

Of these, one the distributed facility becomes the basis for a local organisation of human activities.

The undistributed facility and the transportation element become the basis for regional organisation.

The existence of these two levels of community is responsible for the development of a regional as opposed to local area is “home”.

For the regional community the local area a unique geographical resource to be used for their own purpose.

Where these different viewpoints produce conflicting demands on the same land, a technical solution is required in the form of a set of defined land use relationships which permit the simultaneous expression of both local and regional functions in the same area with as little friction between them possible.

In this case possibilities are different in different parts of the field.

The structural accommodation is more difficult towards the centre where the greeted regional paths converge and where regional facilities come to predominate.

URBAN MORPHOLOGY

The term urban morphology refers to the physical arrangement or structure of the town; its patterns of streets, building blocks, and individual buildings, their different functions, densities and layouts.

A basic approach in studies of urban morphology involves the mapping and description of patterns of internal land uses as a preliminary stage in the analysis of the process operating to produce particular patterns of urban structures.

The models of urban structures are of two kinds: partial and comprehensive.

Partial models are concerned with location of one set of activities, such as residential such as residential or industrial land use, while comprehensive models deal with all activities in the urban area and their inter relationships.

The patterns of urban land use result from a multitude of choices and decisions about locations. These are made by individual’s planners, architects, companies and by both local and central government.

These decisions are influenced predominantly by economic motives.

The figure above shows the offer prices for the three types of potential land use at different distances from the city centre (O).

Bid prices are based on their ability to derive advantage from central location in the city.

Thus, at O, retail use, which is most dependent on accessibility, can outbid other potential users.

However, the offer price curve for retail land use declines more steeply than that of offices or residences, and the distance between A and B from the city centre offices can bid for sites most successfully, while beyond B, towards the urban margin, the offer prices of residential land use is greater than that of either retail or office use.

Thus, there develops an orderly pattern of urban land uses which is closely related to rents, which in turn are influenced by land values.

THE LAND VALUE SURFACE

The land values play an important role in determining patterns of urban land use it is useful to consider the chief influences on land values in any town.

The land value surface, as the overall pattern of values is termed, is essentially a reflection of accessibility within the urban area.

Accessibility is greatest at the city centre; it is also greater along radial and circumferential routes, and especially at their intersections, than it is away from them.

Some parts of the urban area are better served by transport than others the land value surface declines more steeply from the centre in some directions than others.

The characteristics of a typical urban land value surface may be summarized as follows:

Land values reach a great peak at the city centre and decline by varying amounts in different directions from the city centre.

Secondary peaks of higher values occur at major traffic intersections.

High values occur along the major traffic arteries compared with values in the area between such routes.

Although the accessibility is the dominant influence, local site characteristics and other major factors inevitably complicate the simple patterns.

Nevertheless, the general concept of the land value surface provides a useful background for the study of the various land use zones in the city.

B A S I C T E R M I N O LO GY

“ DENSITY PATTERNS”

Population density is a measure of how compact or concentrated a population is.

It takes are of land into account as well as population. Population Density = population per unit area

(unit area is usually measured in Km2 or miles2) Sparsely populated = small number of people per unit

area ( less than 100 people / Km2) Densely Populated = high number of people per unit

area (higher than 100 people / Km2 ) It is important to note that these two classifications and the

numeric cut off of 100 people / Km2 are somewhat arbitrary.

Some books use a middle category moderately populated @ 10-100 people / Km2

FACTORS AFFECTING POPULATION DENSITY AND DISTRIBUTION

CLIMATE Warmer comfortable climates attract people. Notice that most people live in a moderate climate region.

ECONOMICS Population distribution has changed over time. No longer are dense populations around primary resources. Urbanization and the move to the industrial and now the

information ages have changed population distribution.

TRANSPORTATION Coastal regions attracted business and people because of

ocean transportation. It was true for initial settlement and is still true today. Most major cities are located on the coast.

If B does remains similar to A in its space – shape, it will be different in two other important respects – first in its size and second in its density distribution.

As with location, changes in the density at which all activities are carried on follow as a matter of course from changed time – distances.

The general slope of the density gradient depends upon transport efficiency in substituting more peripheral for more central locations.

A new level of efficiency means a flatter slope, a territory larger region, a more spread – out centre, and a lower regional density, assuming of course, that the total population increases less than proportionally to the increase in area and that there are no unusual restrictions on space supply.

New time – distances change potential in every part of the region, throwing in into conflict with actual densities which are past values realised.

The choice is to put things where they belong once more (i.e. in the right amount), or else, in public interest, deliberately to bear the cost of not doing so in the form of unrealized value, inflated value, or subsidy.

MEASURES OF POPULATION DENSITY

Crude population density is a measure of the average numbers of the individuals per unit area.

As an average figure it suffers all the limitations that this implies.

A crude population density provides no information about the extreme values within the territory, and comparisons of the density figures are meaningful only for small areal units such as parishes and communes, but not for large units such as nations or continents.

A crude density figure alone can never be used as an index of overpopulation.

Because of these limitations, various refinements of crude of crude population density are sometimes employed.

The densities can be calculated inhabited or cultivated areas only rather than for gross areas and the latter is called as physiological or nutritional density.

Conversely, the density of the certain sectors of the population can be calculated against total area.

The density figures of the industrial or agrarian sections of the populations and it is referred to as agricultural density.

In the urban area where the high rise blocks of flats invalidated simple relationships between population and area, here room density or average number of persons per room, provides an index widely used by planners and sociologists.

DENSITY OF POPULATIONS AND FLOOR SPACE INDEX

Density of population decreases towards periphery of the city at a diminishing rate with the increase in the distance from the city.

In the vicinity of the city centre, the density drops to zero as the available floor space is entirely occupied by non – residential uses particularly by CBD.

The existing stock of buildings (floor space) acts as constraints on the spatial expansion of the central business use with residential in area surrounding the city centre (PORTION AB) and mixed land use explains the sudden depression in the density curve over PORTION BA.

Density of population decreases steeply over PORTION BC indicating the influence of the proximity to the core in the choice of residential location.

Density curve flattens beyond the point c indicating a low density residential sprawl in peripheral areas.

The gap between the floor space ratio curve and the density curve indicates the changing intensity of use of floor space for non residential use.

In PORTION OB the balance floor space is predominantly occupied by central business use and retail commercial use while in the PORTION BC as also in the peripheral areas, it is occupied by industrial areas, educational areas and other non residential areas.

B A S I C T E R M I N O LO GY

“ LANDUSE CLASSIFICATION & CODING”

The system of urban land use classification is based on the requirements of the various plans as suggested by UDPFI Guidelines.

The perspective plan which is a policy document, need not show very many details of a specific land use and may only show the main use which could be, say, residential or commercial.

In case of a development plan, which is comprehensive plan indicating use of each parcel of land, there is a need to show more details of a specific land use.

It has to indicate for the land designated as, say commercial, further details as to which land is for retail commercial, or for wholesale trade or go downs.

In the case of layouts of projects of a shopping centre further details shall be necessary, indicating which block of retail commercial is for, say, cloth or electronics or vegetables.

Considering this it is suggested that there should be three levels in land use classification as shown under:

LEVEL I - FOR PERSPECTIVE PLANS LEVEL II – FOR DEVELOPMENT PLANS LEVEL III – FOR LAYOUTS OF PROJECTS / SCHEMES In LEVEL III details are a function of the requirements of a

project/scheme and would vary from project to project, only LEVEL I and LEVEL II classification is presented.

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