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Terminologies in Urban Theory - II
Urban economics, Conurbation, Bid rent theory, Concentric zone model, Sector model, Core frame model, Multiple nuclei model, Central Place Theory, Transect, Euclidean zoning, Linear city, Activity centre , Central business district, Town centre, Rural–urban fringe, Habitat fragmentation, Rural flight , Exurb, Urban decay
Urban economics is broadly the economic study of urban areas; as such, it involves using the tools of economics to analyze urban issues such as crime, education, public transit, housing, and local government finance. More narrowly, it is a branch of microeconomics that studies urban spatial structure and the location of households and firms (Quigley 2008).
A conurbation is a region comprising a number of cities, large towns, and other urban areas that, through population growth and physical expansion, have merged to form one continuous urban and industrially developed area. In most cases, a conurbation is a polycentric urban agglomeration, in which transportation has developed to link areas to create a single urban labour market or travel to work area.
Bid rent theory
The bid rent theory is a geographical economic theory that refers to how the price and demand for real estate change as the distance from the central business district (CBD) increases. It states that different land users will compete with one another for land close to the city center. This is based upon the idea that retailestablishments wish to maximize their profitability, so they are much more willing to pay more for land close to the CBD and less for land further away from this area. This theory is based upon the reasoning that the more accessible an area (i.e., the greater the concentration of customers), the more profitable.
Concentric zone model
The Concentric zone model, also known as the Burgess model or the CCD model, is one of the earliest theoretical models to explain urban social structures. It was created by sociologist Ernest Burgess in 1925
The sector model, also known as the Hoyt model, is a model of urban land use proposed in 1939 by economist Homer Hoyt. It is a modification of the concentric zone model of city development. The benefits of the application of this model include the fact it allows for an outward progression of growth. As with all simple models of such complex phenomena its validity is limited.
Core frame model
The Core frame model is a model showing the urban structure of the Central Business District of a town or city. The model was first suggested by Ronald R. Boyce and Edgar M. Horwood in 1959.
The model includes an inner core where land is expensive and used intensively, resulting in vertical development. This area is the focus of the transport system and has a concentrated daytime population. The outer core and frame have lower land values and are less intensively developed.The various land uses are linked to the bid rent theory. The zone of assimilation and zone of discard are together called the zone of transition.
Multiple nuclei model
The multiple nuclei model is an economical model created by Chauncy Harris and Edward Ullman in the 1945 article "The Nature of Cities".
The model describes the layout of a city, based on Chicago. It says that even though a city may have begun with a central business district, or CBD, other smaller CBDs develop on the outskirts of the city near the more valuable housing areas to allow shorter commutes from the outskirts of the city. This creates nodes or nuclei in other parts of the city besides the CBD thus the name multiple nuclei model. Their aim was to produce a more realistic, if more complicated, model. Their main goals in this were to:
- Move away from the concentric zone model
- To better reflect the complex nature of urban areas, especially those of larger size
Central Place Theory
Central Place Theory (CPT) is an attempt to explain the spatial arrangement, size, and number of settlements. The theory was originally published in 1933 by a German geographer Walter Christaller who studied the settlement patterns in southern Germany.
The urban-to-rural transect is an urban planning model created by New Urbanist Andrés Duany. The transect defines a series of zones that transition from sparse rural farmhouses to the dense urban core. Each zone is fractal in that it contains a similar transition from the edge to the center of the neighborhood. The transect is an important part of the New Urbanism and smart growth movements. Duany's firm DPZ has embodied the transect philosophy into their SmartCode generic planning code for municipal ordinances.
The importance of transect planning is particularly seen as a contrast to modern Euclidean zoning and suburban development. In these patterns, large areas are dedicated to a single purpose, such as housing, offices, shopping, and they can only be accessed via major roads. The transect, by contrast, decreases the necessity for long-distance travel by any means.
Single-use zoning, also known as Euclidean zoning, is a practice of urban planning where everyday uses are separated from each other and where land uses of the same type are grouped together. Shops are concentrated in one area, housing in another area, industry in another.
The linear city was an urban plan for an elongated urban formation. The city would consist of a series of functionally specialized parallel sectors. Generally, the city would run parallel to a river and be built so that the dominant wind would blow from the residential areas to the industrial strip. The sectors of a linear city would be:
- a purely segregated zone for railway lines,
- a zone of production and communal enterprises, with related scientific, technical and educational institutions,
- a green belt or buffer zone with major highway,
- a residential zone, including a band of social institutions, a band of residential buildings and a "children's band",
- a park zone, and
- an agricultural zone with gardens and state-run farms
As the city expanded, additional sectors would be added to the end of each band, so that the city would become ever longer, without growing wider.
Activity centre is a term used in urban planning and design for a mixed-use urban area where there is a concentration of commercial and other land uses. For example, the central business districts of cities (CBD) are also known as “Central Activities Districts” (CAD) (also known as Downtown in North America or "Central Activities Zone" in the United Kingdom) in recognition of the fact that commercial functions are not the only things that do or should occur there. The term activity centre can also be used to designate an area for mixed-use development, whatever its current land use happens to be.
Central business district
A central business district (CBD) is the commercial and business centre of a city. In larger cities, it is often synonymous with the city's "financial district". Geographically, it often coincides with the "city centre" or "downtown", but the two concepts are separate: many cities have a central business district located away from its commercial or cultural city centre or downtown. Both the CBD and the city centre or downtown may also coincide with the central activities district
The town centre is the term used to refer to the commercial or geographical centre or core area of a town.
Town centres are traditionally associated with shopping or retail. They are also the centre of communications with major public transport hubs such as train or bus stations. Public buildings including town halls,museums and libraries are often found in town centres.
Town centres are symbolic to settlements as a whole and often contain the best examples of architecture, main landmark buildings, statues and public spaces associated with a place
The rural–urban fringe, also known as the outskirts or the urban hinterland, can be described as the "landscape interface between town and country", or also as the transition zone where urban and rural uses mix and often clash. Alternatively, it can be viewed as a landscape type in its own right, one forged from an interaction of urban and rural land uses.
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Habitat fragmentation can be caused by geological processes that slowly alter the layout of the physical environment(suspected of being one of the major causes of speciation), or by human activity such as land conversion, which can alter the environment much faster and causes extinctions of many species.
Rural flight (or rural exodus) is the migratory pattern of peoples from rural areas into urban areas. It is urbanization seen from the rural perspective.
In modern times, it often occurs in a region following the industrialization of agriculture—when fewer people are needed to bring the same amount of agricultural output to market—and related agricultural services and industries are consolidated. Rural flight is exacerbated when the population decline leads to the loss of rural services (such as business enterprises and schools), which leads to greater loss of population as people leave to seek those features.
This phenomenon was first articulated through Ernst Georg Ravenstein's Laws of migration in the 1880s, upon which modern theories are based.
The expression exurb (for "extra-urban") was coined by Auguste Comte Spectorsky in his 1955 book The Exurbanites to describe the ring of prosperous communities beyond the suburbs that are commuter towns for an urban area.Most exurbs serve as commuter towns, but most commuter towns are not exurban.
Exurbs vary in wealth and education level. In the United States, exurban areas typically have much higher college education levels than closer-in suburbs, though this is not necessarily the case in other countries. They typically have average incomes much higher than nearby rural counties. Depending on local circumstances, some exurbs have higher poverty levels than suburbs nearer the city.
Urban decay (also known as urban rot and urban blight) is the process whereby a previously functioning city, or part of a city, falls into disrepair and decrepitude. It may feature deindustrialization, depopulation or changing population, restructuring, abandoned buildings, high local unemployment, fragmented families, politicaldisenfranchisement, crime, and a desolate, inhospitable city landscape
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