Rahat Al Faysal
Email :rahatal_faysal@yahoo.com
The term Urban Expansion, Urban Intensification,
Conurbation and Urban Gentrification are related one another. Expansion and
Intensification occurs for the development of the Conurbation or Urban areas
and Gentrification is used to displacement of the lower income people by the
middle-class or affluent people within a Conurbation or Urban areas.
URBAN
This study examined the dynamics
of global urban expansion by defining a new
universe of 3,943 cities with
population in excess of 100,000 and drawing a stratified
global sample of 120 cities from
this universe. Population data and satellite images for
two time periods⎯a decade apart⎯were obtained and analyzed, and several
measures
of urban extent and expansion⎯among them the built-up area of
cities and the average
density of the built-up area⎯were calculated. The Central
message of this
study is quite clear: Developing
country cities should be making realistic⎯yet
minimal⎯plans for urban expansion,
designating adequate areas for accommodating
the projected expansion,
investing wisely in basic trunk infrastructure to serve this
expansion, and protecting sensitive land from
incursion by new urban development.
The magnitude of global urban expansion
The population in
developing-country cities is expected to double in the next thirty
years: from some 2 billion in
2000 to almost 4 billion in 2030.1 According to our own
preliminary estimates, cities
with populations in excess of 100,000 contained 1.7 billion
people in 2000, and their total
built-up area ⎯at average
densities of some 8,000 persons
per square kilometer2⎯was of the order of 200,000
square kilometers at that time. If
average densities continue to
decline at the annual rate of 1.7%⎯as
they have during the
past decade⎯the built-up area of
developing-country cities will increase to more than
600,000 square kilometers by
2030. In other words, by 2030 these cities can be expected
to triple their land area, with
every new resident converting, on average, some 160
square meters of non-urban to
urban land during the coming years.
In parallel, the urban population
of industrialized countries is now expected to grow
by 11% in the next thirty years:
from some 0.9 billion to 1 billion.3 According to our own
provisional estimates, cities
with population in excess of 100,000 contained some 600
million people in 2000, and their
total built-up area ⎯at average
densities of almost
3,000 persons per square
kilometer4⎯was of the order
of 200,000 square kilometers at
that time. If average densities
continue to decline at the annual rate of 2.2%⎯as they
have during the past decade⎯the built-up area of
industrialized-country cities will
increase to some 500,000 square
kilometers by 2030.
The central objective of the
Urban Growth Management Initiative is to examine the
available policy options for
confronting the projected urban expansion in the cities of
developing countries. In other
words, it seeks an answer to the question of what can
and should be done about it. This
demands gaining a better understanding of the key
dimensions of this expansion as
well as of the forces that are driving it globally,
regionally and locally, so as to
be able to consider carefully the kinds of policies that are
likely to be effective,
efficient, equitable and sustainable, while keeping in mind that
such policies may be quite
different from those available or of interest in industrializedcountry
cities.
The form of
urban expansion
Urban expansion takes places in
substantially different forms. In any given city, new
urban expansion can take place
with the same densities (persons per square kilometer)
as those prevailing in existing
built-up areas, with increased densities, or with reduced
densities. It can take place
through the redevelopment of built-up areas at higher
densities, through infill of the
remaining open spaces in already built-up areas, or
through new “greenfield”
development in areas previously in non-urban use. It can encroach upon
wetlands, watersheds, forests, and other
sensitive environments that need
to be protected, as well as upon farms, fields, and
orchards surrounding the city.
And it can thus reduce, maintain or increase open space
in and around the city.
One of the aims of the study is
to examine the different forms that urban expansion
takes by looking at the size and
shape of built-up areas in a global sample of 120 cities
and associating them with their
populations.
Urban expansion
policies
There are three groups of policy
areas that have a bearing on shaping urban
expansion:
Ø
Policies
that affect or seek to affect rural−urban (or
international)
migration, both
directly and indirectly;
Ø
Policies
that affect or seek to affect the distribution of urban populations
among cities; and
Ø
Policies
that affect or seek to affect the process of urban development in
individual cities
and metropolitan areas.
The forces
shaping urban expansion
The motivations for pursuing
policies of the first type are many⎯from
concerns that
cities are already too big and
bursting at their seams, to the romantic longings for a
wholesome village lifestyle, and
to the need to focus development on rural areas, where
the majority of poor people live
and work. Policy prescriptions have ranged from
increasing agricultural
productivity and improving rural education to restricting the movement to
cities by requiring residence permits.
URBAN
INTENSIFICATION
The Provincial Policies directing
communities to begin to plan for growth within existing municipal boundaries where
services of all kinds exist has generated a discussion of how new forms of development can occur. The objective of the
policies is to maximize the benefits of existing services by increasing the
number of people that use them. New development occurring in areas that are already
built up naturally results in a more intensive use and this process is defined
as intensification.
As intensification takes place,
it is critical to note urban design principles that should be adhered to as a
means of assuring a consistent approach to the design of new infill buildings.
An important objective of these new forms of development is to develop
sustainable communities through well-designed built form and public realm,
creating opportunities for a positive and lively pedestrian experience. As a
result the following Urban Design Principles should be recognized:
Ø Buildings should
be developed at an appropriate scale for the context;
Ø Ensure a
transition in scale of buildings with surrounding community;
Ø Provide a
variety of building massing and heights;
Ø Mass buildings
to frame the streets;
Ø Design buildings
with ground related uses that enliventhe street
Ø Ensure the
design and detailing of window openings doorways, and balconies are at an
appropriate , pedestrian scale; and
Ø Integrate
parking areas into the design of the development, hidden from the street.
The Problem –
Urban Intensification
Urban intensification –
increasing the density of dwellings within existing built areas – has become a
principle of planning policy and practice across many developed countries. It
is usually accompanied by a range of other policies, some transport-related
(e.g. public transport improvements), some related to other aspects of the
urban environment.
The evolution of policy towards
intensification has been influenced by a substantial literature on the
relationships between the urban form and transport outcomes.
Average household sizes have been
falling across many developed countries in recent years. A distinction should
be drawn therefore between intensification which increases the population
density of an area, and a limited intensification of dwellings which serves
only to attenuate a decline in population density. In seeking to identify an
underlying principle, this article will define urban intensification as an
increase in the density of both dwellings and population. The principle will
have slightly different implications for the other, more limited, form of
intensification.
Policy
Implications
From a policy perspective, a key
question which emerges from this analysis is whether, through additional
measures it is possible to intensify without significantly increasing local
concentrations of traffic.These may be-
1.
Policymakers
may consider local concentrations of traffic an acceptable side-effect where
intensification of that site forms part of a strategy aimed at achieving modal
shift and other objectives at the city-wide level – although residents of
surrounding areas are unlikely to share that view. One obvious context is
intensification around public transport routes, where population density around
stops exerts a strong influence on ridership and the financial viability of the
service (TRB, 2009).
2.
Alternatively more radical measures may be
considered to overcome the traffic effects of intensification.
3.
Reductions in residential parking provision can be
one of the most effective tools, provided effective controls exist to prevent
overspill parking and reduce levels of car ownership.
4.
Non-residential parking restrictions – often part of
„smart growth‟ policies – can reduce inward vehicle trips to mixed use areas,
although these are unlikely to have much effect on traffic generated by
households within the area, unless they are accompanied by residential parking
restrictions.
5.
Physical restrictions on the circulation of motor
vehicles have also been effective in certain city centre
Conclusions
Although the evidence on the
specific outcomes of intensification is currently limited, the weight of
evidence reviewed here suggests that an inelastic negative relationship between
population density and vehicle use is common, across several developed
countries. This implies that planning policies which increase population
densities will, under „normal circumstances‟ reduce overall vehicle use, but
increase its concentration in the intensified areas, causing a range of local
environmental and social problems, unless significant steps are taken to
constrain the generation of additional traffic. It is important that this
paradox of intensification is recognised, to avoid false expectations and focus
attention on the other policies which must accompany intensification if
environmental and social goals are to be achieved.
CONURBATION
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.
The term "conurbation" was coined as a neologism in 1915 by
Patrick Geddes in his book Cities in Evolution. He drew attention to the
ability of the (then) new technology of electric power and motorised transport
to allow cities to spread and agglomerate together, and gave as examples
"Midlandton” in England, the Ruhr in Germany, Randstad in the Netherlands,
New York-Boston in the United States,
the Greater Tokyo Area and Taiheiyō Belt in Japan and NCR of Delhi in India.
A conurbation can be confused with a metropolitan area. As the term is used
in North America, a metropolitan area can be defined by the Census Bureau or it
may consist of a central city and its suburbs, while a conurbation consists of
adjacent metropolitan areas that are connected with one another by
urbanization.Internationally, the term "urban agglomeration" is often
used to convey a similar meaning to "conurbation".A conurbation
should also be contrasted with a megalopolis, where the urban areas are close
but not physically contiguous and where the merging of labour markets has not
yet developed.
URBAN
GENTRIFICATION
Gentrification is
defined as the process by which wealthier (mostly middle-income) people move
into, renovate, and restore housing and sometimes businesses in inner cities or
other deteriorated areas formerly home to poorer people.
(Sociology) Brit
a process by which middle-class people take up residence in a traditionally
working-class area of a city, changing the
character of the area.
It is the informal process of revitalizing an older
and deteriorated neighborhood into more upscale homes owned by more affluent
occupants. The first step is usually taken by young professionals seeking
affordable housing in an urban setting, who immediately begin using disposable
income to upgrade their properties .Their efforts attract other like-minded
home buyers. Eventually the neighborhood reaches a point where the existing
homeowners can afford to sell their properties and buy elsewhere, but they
can't afford to pay the increasing property taxes. The process gains momentum
at that point, with former apartment buildings being converted to condos,
single-family residences undergoing complete renovations, and the entire
neighborhood changing to middle class or upper-middle class. It is
controversial, with some claiming it destroys the ethnicity and integrity of
many older neighborhoods, all in the guise of ethnocentric notions of
“improvement.”
Urban gentrification occasionally
changes the culturally heterogeneous character of a community or neighborhood
to a more economically homogeneous community that some describe as having a
suburban character. This process is sometimes made feasible by
government-sponsored private real estate investment repairing the local infrastructure,
via deferred taxes, mortgages for poor and for first-time house buyers, and
financial incentives for the owners of decayed rental housing. Once in place,
these economic development actions tend to reduce local property crime,
increase property values and prices, and increase tax revenues.
References:
1 .The character of
Urban Intensification : A report on research projects funded by Australian Research
Council,2002-2010, Kim Dovey and lan Woodcock, Faculty of Architecture,
Building and Planning University of Melbourne
2.Gomez-Ibanez, J.A
(1991) A global view of Automobile
Dependences.Journal of the American Planning Association 57(3)376
3. Gordon,I,(1997)
Densities , Urban form travel behavior.Town and Country Planning,66,(9)
239-241.
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