UNITY UNIVERSITY COLLEGE
Department of Architecture and Urban planning
URBAN PLANNING II
NATURE OF CITIES URBAN LIFE CYCLE
1
Course objective
At the end of the session participants will be
able to -;
•Explain what the characteristics and nature of cities
are
•Describing the modalities of city design respecting
their natural elements
•Describe the urban life cycle
•Explain the causes of declining and revival of cities
Urban life cycle
The urban dynamics/a theory of growth and
decline
The influence of economic and social change on
the dynamics of urban system
Some exogenous variables like demography,
politics, social value and technology /
fundamental developments influence the
evolution of cities
Urban life cycle
After conducting a study on some FUR
/functional urban regions/ in Europe experts
have identified 4 stages of development
Urban life cycle
I. Urbanisation
A process by which people are concentrated in
an area called urban, in which the growth of
the core dominates its ring and all urban
activities are concentrated
The stage of urbanisation runs parallel to the
process of industrialization attracting migrants
from rural areas
Urban life cycle
High priority for economic growth, location of
large scale industries, development of
transport system are the main features of this
stage
How ever this concentration in the long term
became less attractive for residents and for
business groups due to high congestion
And this led to suburbanisation
Urban life cycle
II. Suburbanisation/sprawl
Featured by spatial deconcentration and the
ring growth dominating the center
It’s a period in which suburban municipalities
increase their number of population while the
core losing its inhabitants
It is characterised by economic growth car
ownership and strong expansion of
transportation system by the government
Urban life cycle
Consequences
High commuting
Traffic congestion specially at peak hours
Unprofitability of public transport
Thus
Large agglomerations fall from the
suburbanisation and exercise a new trade
disurbanisation
Urban life cycle
III. Disurbanization
A stage where metropolitan areas lose their population and employment
because rapid out ward migration to the smaller municipalities at a distance
which is followed by public deficits due to shrinking tax base
And this because mainly of first
• congestion which makes work places and central provisions less accessible
• Lack of space and higher rents and living costs which makes minor towns
more attractive
• Minor towns which are more attractive safe and with good living and
working conditions
The idea of reversing the urban decline creating
competitiveness
Urban life cycle
IV. Reurbanisation
To mean the recovery of the large core
Revitalisation of cities:- adopting policies to
upgrade cities attraction for the market parties
and brig back the people who previously left
Urban life cycle
Principles
Improving the quality of the environment
Rehabilitation of the existing house stock
Improve the traffic situation
Improve facilities
Upgrading the social infrastructure
Restoring the urban economy
Urban life cycle
Policy issues
•High economic potentials – creating jobs and improve income
•Improving the quality of living and working environment
•Better accessibility of the city for market potentials
•A balanced social distribution of income
•Community participation
Urban nature and city design
Urban nature and city design
People have different perception about nature
but the principal question to be answered are;
Does nature influence human development?
Is it man the sole architect who influence nature
in which he lives?
Does man exist with in nature or apart?
Answering these questions will lead to how
cities are perceived, planned and built
Urban nature and city design
Urban planners have viewed natural forces
apart from cities rather than as its integral
part
Thus
Most cities have failed to use the full potential
of nature in creating a healthy, economical
and beautiful urban environment (Anne Spirin)
Urban nature and city design
The city is part of nature. Recognizing this fact
has a powerful implication on how the city is
built.
Experts engaged on city development have
known more about urban nature;
…Morphology, shape of its buildings, parks, road
structure ….,
but little of this information's are used to build
cities
Urban nature and city design
“……Man is everywhere a disturbing agent. Wherever he plants
his foot the harmonies of nature turned to discords….”
/George Perkins 1864/
“………..we ought never to undertake any thing that is not exactly
agreeable to nature … for nature if you force or wrest her out
of way what ever strength you have …… will at last overcome
and break through with all oppositions and hindrances…..”
According to Francis Bacon
Nature is only to be commanded by obeying her
Urban nature and city design
By the nineteenth century rapid urbanization due to
enormous industrialization produces alarming changes
in cities of the developing world
Human impact on nature was out of control
Principal urban natural components
air- quality, comfort, circulation, heat….
land-morphology and geology
water- storm, drainage, flood,…
urban life- wild life, plant community…
ecosystems- a process linking air, water of the city and
the organism that live with in it
Urban nature and city design
John Evelyn's proposal for the 17th century city of
London
Identification of pollutants
The assumption is to study the climatic condition
/direction of the wind with in the city/
• prohibition of sulfur coal
• relocation of polluting industries
• plantation of trees and flowers….
Urban nature and city design
According to Marsh
Man`s economy be designed to work with
nature
>>> Reclaiming and reoccupying lands laid
waste by human aggression or cruelty…
and the task is to become a co-worker with
nature in the reconstruction of the damaged
fabrics
Urban nature and city design
The application of marsh's principle by Fredrick
Law /the case of Boston/
Improving the urban environment
Green and parks
The employment of natural elements/water
body, rather than a masonry flood storage is
more effective and attractive which can be an
amenity rather than an eyesore
Urban nature and city design
The sanitary reform movement established by Olmsted
>>> the American city planning movement
Basic Ideas cities as natural elements should
accommodate and be;
• airy
• verdant setting
• free from excessive crowd
• dry and drained
• abundant parks and trees
• enough places for out door games…..
Urban nature and city design
Other ideologists
Ebenezer Howard & Patrick Geddes
>>>> Garden cities
Mumford
>>>>>> urban form is an expression of the natural and
cultural history of a region
Lynch
Good city >>> How well it sustain life / vitality
>>> How clearly it is perceived in space and
time /sense
>>> How well environment and behaviour fit
accessibility, control, efficiency, justice
Urban nature and city design
The mental sense of connection with nature is a
basic human satisfaction, the most profound
aspect of sensibility…. The movements of sun,
tides, the cycles of weeds and insects and men
can also be celebrated along the city
pavements. /Lynch
Urban nature and city design
Integrating city design with urban nature
The case of Texas, Denver(America) and Stuttgart/Germany/
Texas
20000 acres with about 150000 people
Flat with poor drainage system
Subsided about 10 feet in some places
Proposed solution…. A natural drainage system
Urban nature and city design
The planning principles
•Major road ways and commercial development to be
located on ridgelines and higher elevations
•Floodplains and recharge soils to be preserved in parks and
public rights of way
•Roads golf courses and parks hold storm water over sandy
soils to enhance absorption
•Flood plains and drained areas to be used as an open
space
•Plantation of trees on flood plains
Urban nature and city design
Denver
The principle Is the same with that of Texas
But here the planning principle insists that roof
tops, plazas and parkings to detain storm water
instead of ponds and soil
Urban nature and city design
Stuttgart /Germany/
An industrial city with 630000 pop
Lies in a valley plagued by persistent inversion so
frequent unhealthy concentration of air pollutants
Principal focus areas
•Climatological studies mainly on air circulation
pattern of the town
•Energy conservation
Urban nature and city design
Creating a hill- to- valley air movement to ventilate the lower
lands
Forming radial open spaces that extends from the forest area
to the heart of the town for ventilation purposes
Converting parks from asphalt to turf block
Introducing roof gardens and wet-roofs /ponding one or two
inches of water
Restricting the use of oil and coal in areas where air
circulation is poor
Steam produced while burring municipal garbage is used to
heat individual houses and commerce's
By products of cinders and ash are used in construction of
road beds
THANKS
