Urban planning





Urban, city, or town planning, deals with design of the built environment
from the municipal and metropolitan perspective. Other professions deal in
more detail with a smaller scale of development, namely architecture and
urban design. Regional planning deals with a still larger environment, at a
less detailed level. The Greek Hippodamus is often considered the father of
city planning, for his design of Miletus, though examples of planned cities
permeate antiquity. Muslims are thought to have originated the idea of
formal zoning (see haram and hima and the more general notion of khalifa, or
"stewardship" from which they arise).

City planning embraces the organisation, or conscious influencing, of
land-use distribution in an area already built-up or intended to become
built-up.

In ancient times, Romans used a consolidated scheme for city planning,
developed for military defense and civil convenience. Effectively, many
European towns still preserve the essence of these schemes, as in Turin. The
basic plan is a central plaza with city services, surrounded by a compact
grid of streets and wrapped in a wall for defense. To reduce travel times,
two diagonal streets cross the square grid corner-to-corner, passing through
the central square. A river usually flows through the sity, to provide water
and transport, and carry away sewage, even in sieges.

Planning and aesthetics

In developed countries there has been a backlash against excessive man-made
clutter in the environment, such as bollards, signs and hoardings. Other
issues that generate strong debate amongst urban designers are tensions
between peripheral growth, increased housing density and planned new
settlements. There are also unending debates about the benefits of mixing
tenures and land uses, versus the benefits of distinguishing geographic
zones where different uses predominate.

Successful urban planning considers character, of "home" and "sense of
place", local identity, respect for natural, artistic and historic heritage,
an understanding of the "urban grain" or "townscape," pedestrians and other
modes of traffic, utilities and natural hazards, such as flood zones.

Some say that the medieval piazza and arcade are the most widely appreciated
elements of successful urban design, as demonstrated by the Italian cities
of Siena and Bologna.

While it is rare that cities are planned from scratch (and, in case, with
some risk of unsuccessful examples like for Brasilia), planners are
important in managing the growth of cities, applying tools like zoning to
manage the uses of land, and growth management to manage the pace of
development. When examined historically, many of the cities now thought to
be most beautiful are the result of dense, long lasting systems of
prohibitions and guidance about building sizes, uses and features. These
allowed substantial freedoms, yet enforce styles, safety, and often
materials in practical ways. Many conventional planning techniques are being
repackaged as smart growth.

There are some cities that have been planned from conception, and while the
plans often don't turn out quite as planned, evidence of the initial plan
often remains. See List of planned cities. Some of the most successful
planned cities consist of cells that include park-space, commerce and
housing, and then repeat the cell. Usually cells are separated by streets.
Often each cell has unique monuments and gardening in the park, and unique
gates or boundary-markers for the edges of the cell. The commercial areas
naturally become diverse. These differences help instill a sense of place,
while the similarities of the cells make each place in the city familiar.

Many urban areas show little sign of ever having being planned in any
coherent or socially-aware way. Buildings and spaces may reflect the
different priorities of a different era, or simply demonstrate an undue
(anti-social or environmentally-insensitive) emphasis on the priorities of
the organisation or individual that paid for their construction. Left-over
parts of a town or city that appear to serve no particular purpose have been
labelled by the pejorative acronym "SLOAP" meaning Space Left Over After
Planning. Unfortunately such spaces are all too common, particularly in
suburban areas, and planners, businesses, politicians, land agents and
communities all have a duty to consider how these flaws in the urban fabric
might be repaired.

Planning and safety

Many cities are constructed in places subject to flood, storm surges,
extreme weather or war. City planners can cope with these. If the dangers
can be localized (for flood or storm surge), the affected regions can be
made into parkland or greenbelt, often with lovely results. Another
practical method is simply to build the city on ridges,a nd the aprs and
farms in valleys.

Extreme weather, flood, war or other emergencies can often be greatly
mitigated with secure evacuation routes and emergency operations centers.
These are so inexpensive and unintrusive that they're a reasonable
precaution for any urban space.

Many cities also have planned, built safety features, such as levees,
retaining walls, and shelters.

Some planning methods might help an elite control ordinary citizens. This
was certainly the case of Rome (Italy), where Fascism in the 1930s created
ex novo many new suburbs in order to concentrate criminals and poorer
classes away from the elegant town. France currently uses similar methods to
control ethnic-arabic groups on welfare.

In recent years, practitioners have also been expected to maximise the
accessibility of an area to people with different abilities, practising the
notion of "inclusive design," to anticipate criminal behaviour and
consequently to "design-out crime" and to consider "traffic calming" or
"pedestrianisation" as ways of making urban life more bearable.

City planning tries to control criminality with structures designed from
theories like socio-architecture or environmental determinism. These
theories say that an urban environment can influence individuals' obedience
to social rules. The theories often say that pschological pressure develops
in more densely developed, unadorned areas. This stress causes some crimes
and some use of illegal drugs. The antidote is usually more individual space
and better, more beautiful design in place of functionalism.

Other social theories point out that in England and most countries since the
18th century, the transformation of societies from rural agriculture to
industry caused a difficult adaptation to urban living. These theories
emphasize that many planning policies ignore personal tensions, forcing
individuals to live in a condition of perpetual extraneity to their cities.
Many people therefore lack the comfort of feeling "at home" when at home.
Often these theorists seek a reconsideration of commonly used "standards"
that rationalise the outcomes of a free (relatively unregulated) market.

Planning and transportation

There is a direct, well-researched connection between the density of an
urban environment, and the amount of transportation into that environment.
Good quality transport is often followed by development. Development beyond
a certain density can quickly overcrowd transport.

Good planning attempts to place high densities near high-volume
transportation. For example some cities permit commerce and multistory
apartment buildings only within one block of train stations and four-lane
boulevards, and require single-family dwellings and parks to be
farther-away.

Densities are usually measured as the floor area of buildings divided by the
land area. Ratios below 1.5 are low density. Ratios above five are very high
density. Most exurbs are below two, while most city centers are well above
five. Walk-up apartments with basement garages can easily achieve a density
of three. Skyscrapers easily achieve densities of thirty or more. Higher
densities tempt developers with higher profits. Cities try to lower
densities to reduce infrastructure costs.

Automobiles are well suited to serve densities as high as 1.5 with basic
limited-access highways. Innovations such as car-pool lanes and ruch-hour
use taxes may get automobiles to densities as high as 2.5.

Densities above 5 are well-served by trains. Most such areas were actually
developed in response to trains in the middle 1800s, and have large
historical riderships that have never used automobiles.

The problem is that there is a no-mans-land of densities between about two
and five that causes severe traffic jams of automobiles, yet are too low to
be served by trains or light rail. The conventional solution is to use
busses, but these and light rail systems normally fail when automobiles are
available, achieving less than 1% ridership. Some theoretricians speculate
that personal rapid transit might coax people from their automobiles, and
yet effectively serve intermediate densities, but this has not been
demonstrated. The Lewis-Mogridge Position claims that increasing road space
is not an effective way of relieving traffic jams.

Planning and suburbanization

In some countries declining satisfaction with the urban environment is held
to blame for continuing migration to smaller towns and rural areas Urban
Exodus, so successful urban planning can bring benefits to a much larger
hinterland or city region and help to reduce both congestion along
transportation routes and the wastage of energy implied by excessive commuting.

A strong belief that the behaviour of individuals living in or frequenting
an area can be heavily influenced by its physical design and layout is
called environmental determinism.

Planning and the Environment

Arcology seeks to unify the fields of ecology and architecture, especially
landscape architecture, to achieve a harmonious environment for all living
things. On a small scale, the eco-village theory has become popular, as it
emphasizes a traditional 100-140 person scale for communities.

In most advanced urban or village planning models, local context is
critical. In many, gardening assumes a central role not only in agriculture
but in the daily life of citizens. A series of related movements including
green anarchism, eco-anarchism, eco-feminism and Slow Food have put this in
a political context as part of a focus on smaller systems of resource
extraction, and waste disposal, ideally as part of living machines which do
such recycling automatically, just as nature does. The modern theory of
natural capital emphasizes this as the primary difference between natural
and infrastructural capital, and seeks an economic basis for rationalizing a
move back towards smaller village units.