Friday, January 11, 2008
Urban planning
Urban, city, or town planning is the discipline of land use planning which explores several aspects of the built and social environments of municipalities and communities. Other professions deal in more detail with a smaller scale of development, namely architecture, landscape architecture and urban design. Regional planning deals with a still larger environment, at a less detailed level.
Another key role of urban planning is urban renewal, and re-generation of inner cities by adapting urban planning methods to existing cities suffering from long-term infrastructural decay.
Urban planning is concerned with the ordering and design of settlements, from the smallest towns to the world's largest cities. Shown here is Hong Kong's CBD.
HistoryUrban planning as an organized profession has existed for less than a century, however most settlements and cities have displayed various degrees of forethought and conscious design in their layout and functioning.
As agriculture replaced a nomadic existence, permanent human settlements, and larger settlements began to appear. These early cities became centres for trade, defense, and politics and as centers for distributing the agricultural surplus a settled farming society produces.
Cities laid out with forethought and design permeate antiquity. Perhaps the earliest of these were those of the ancient Mesopotamian and Harrapan civilizations of the third century BCE.Ur located near the Euphrates and Tigris rivers in modern day Iraq and some ancient cities of the Indus Valley in modern day India are perhaps the arliest examples of deliberately planned and managed cities in history. The streets of these early cities were often paved and laid out at right angles in a grid attern. There was also with a hierarchy of streets (commercial boulevards to small residential alleyways). In Harrapan settlements, archaeological evidence suggests the houses were laid out to protect from noise, odors, and thieves, and had their own wells, and sanitation. Ancient cities often had drainage, large granaries, and well-developed urban sanitation The Greek Hippodamus (c. 407 BC) is widely considered the father of city planning in the West, for his design of Miletus; Alexander commissioned him to lay out Alexandria, the grandest example of idealized urban planning of the Mediterranean world, where regularity was aided in large part by its level site near a mouth of the Nile.
The ancient Romans used a consolidated scheme for city planning, developed for military defense and civil convenience. The basic plan is a central plaza with city services, surrounded by a compact rectilinear 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 city, to provide water and transport, and carry away sewage, even in sieges.[citation needed] Effectively, many European towns still preserve the essence of these schemes, as in Turin.The Romans had a very logical way of designing their cities. They put all the streets at right angles, set up in a square grid. All the roads were equal in width and length except for two. These two roads formed the center of the grid and intersected in the middle. One went East/West, the other North/South. They were slightly wider than the others. All roads were made of carefully fitted stones and smaller hard packed stones. Bridges were also onstructed where needed. Each square marked by four roads was called an insulae. An insulae was the Roman equivalent of a city block. Each insulae was 80 yards square. The land of each insulae was divided up. As the city developed, each insulae would eventually be filled with buildings of various shapes and sizes and would be crisscrossed with back roads and alleys. Most insulae were given to the first settlers of a budding new Roman city, but each person had to pay for the building of their own houses. The city was surrounded by a wall to protect the city from invaders and other enemies, and to mark the cities limits. Area outside of the walls and city limits was left for farmland. At the end of each main road, there was a large gateway with atchtowers. A portcullis covered the opening when the city was under siege. Other watchtowers were constructed around the rest of the city’s wall. An aqueduct was built outside of the cities walls. This brought in the water necessary for the cities functioning.
The idea of rational planning collapsed with the idea of the res publica in the European Early Middle Ages. Round a fortress or fortified abbey or next to a Roman nucleus — sometimes itself abandoned— urban growth occurred "like the annular rings of a tree" whether in an extended village or the center of a larger city. Since the new center was often on high, defensible ground, the city plan took on an organic character, following the irregularities of elevation contours like the shapes that result from agricultural terracing.
The ideal centrally-planned urban space: Sposalizio by Raphael, 1504
The ideal city resurfaced in the Early Renaissance in Florence, where the star-shaped city plan was adapted from the new cannon-resistant star fort. The star-shaped fortification had a formative influence on the patterning of Renaissance urban planning: "The Renaissance was hypnotized by one city type which for a century and a half— from Filarete to Scamozzi— was impressed upon utopian schemes: this is the star-shaped city" Radial streets extend outward from a defined center of military, communal or spiritual power. Only in ideal cities did a centrally-planned structure stand at the heart, as in Raphael's Sposalizio of 1504 (illustration); as built, the unique example of a rationally-planned quattrocento new city center, that of Vigevano, 1493-95, resembles a closed space instead, surrounded by arcading. Filarete's ideal city, building on hints in Leone Battista Alberti's De re aedificatoria, was named "Sforzinda" in compliment to his patron; its twelve-pointed shape, circumscribable by a "perfect" Pythagorean figure, the circle, takes no heed of its undulating terrain in Filarete's manuscript.
The true heirs of Greek rational planning were the Muslims, who 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),[citation needed] although modern usage in the West largely dates from the ideas of the Congrès Internationaux d'Architecture Moderne.
Many cities in Central American civilizations also engineered urban planning in their cities including sewage systems and running water. Mexico-Tenochtitlan, was the capital of the Aztec empire, built on an island in Lake Texcoco in what is now the Federal District in central Mexico. At its height, Tenochtitlan was one of the largest cities in the world, with close to 250,000 inhabitants.[citation needed]
In developed countries (Western Europe, North America, Japan and Australasia) during the last two centuries, planning and architecture can be said to have gone through various stages of general consensus. Firstly there was the industrialised city of the 19th century, where control of building was largely held by businesses and the wealthy elite. Around the turn of the 20th century there began to be a movement for providing people, and factory workers in particular, with healthier environments. The concept of garden cities arose and some model towns were built, such as Letchworth and Welwyn Garden City the world's first garden cities, in Hertfordshire, UK. However, these were principally small scale in size, typically dealing with only a few thousand residents.
It wasn't until the 1920s when modernism began to surface. Based on the ideas of Le Corbusier and utilising new skyscraper building techniques, the modernist city stood for the elimination of disorder, congestion and the small scale, replacing them instead with preplanned and widely spaced freeways and tower blocks set within gardens. There were plans for large scale rebuilding of cities, such as the Plan Voisin (based on Le Corbusier's Ville Contemporaine), which proposed clearing and rebuilding most of central Paris. No large scale plans were implemented until after World War II however. Throughout the late 1940s and 1950s, housing shortages caused by war destructions led many cities around the world to build substantial amounts of government housing. Planners at the time used the opportunity to implement the modernist ideal of towers surrounded by gardens. The most prominent example of an entire modernist city is Brasilia, constructed between 1956 and 1960 in Brazil.
By the late 1960s and early 1970s, many planners were coming to realise that the imposition of modernist clean lines and a lack of human scale also tended to sap vitality from the community. This was expressed in high crime and social problems within these planned neighbourhoods. Modernism can be said to have ended in the 1970s when the construction of the cheap, uniform tower blocks ended in many countries, such as Britain and France. Since then many have been demolished and in their way more conventional housing has been built. Rather than attempting to eliminate all disorder, planning now concentrates on individualism and diversity in society and the economy. This is the post-modernist era.
Minimally-planned cities still exist. Houston is an example of a large city (with a metropolitan population of 5.5 million) in a developed country, without a comprehensive zoning ordinance. Houston does, however, have many of the land use restrictions covered by traditional zoning regulations, such as restrictions on development density and parking requirements, even though specific land uses are not regulated. Moreover, private-sector developers have used subdivision covenants and deed restrictions effectively to create the same kinds of land use restrictions found in most municipal zoning laws. Houston voters have rejected proposals for a comprehensive zoning ordinance three times since 1948. Even without zoning in its traditional sense, metropolitan Houston displays similar land use patterns at the macro scale to regions comparable in age and population that do have zoning, such as Dallas. This suggests that factors outside the regulatory environment, such as the provision of urban infrastructure and methods of financing development, may play a greater role in the way American cities are developed than does zoning.
Sustainable development and Sustainability
Sustainable development and sustainability have become buzzwords in the planning industry, with the recognition that present ways of consumption and living have led to problems like the overuse of natural resources, ecosystem destruction, urban heat islands, pollution, growing inequality in cities, the degradation of human living conditions and human-induced climate change. Planners have, as a result, taken to advocating for the development of sustainable cities
However, the notion of sustainable development can be considered as rather recent and evolving, with many questions surrounding this concept. That said, it is often not difficult to recognise what are 'unsustainable' forms of lifestyles, and urban planning is recognised to play a crucial position in the development of sustainable cities.
Stephen Wheeler, in his 1998 article, suggests a definition for sustainable urban development to be as "development that improves the long-term social and ecological health of cities and towns." He goes on to suggest a framework that might help all to better understand what a 'sustainable' city might look like. These include compact, efficient land use; less automobile use yet with better access; efficient resource use, less pollution and waste; the restoration of natural systems; good housing and living environments; a healthy social ecology; sustainable economics; community participation and involvement; and preservation of local culture and wisdom.
The difficult challenge facing planners comes with the implementation of sustainability visions, policy and programmes, and in the midst of doing so, the need to modify institutions to achieve these goals. This is still being worked out by urban planners.
Aspects of planning
Aesthetics
Towns and cities have been planned with aesthetics in mind, here in Bath (England), 18th century private sector development was designed to appear attractive.
In developed countries there has been a backlash against excessive man-made clutter in the environment, such as signposts, 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 argue 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[citation needed].
While it is rare that cities are planned from scratch, 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 using the contemporary term, smart growth.
There are some cities that have been planned from conception, and while the results often don't turn out quite as planned, evidence of the initial plan often remains. (See List of planned cities)
Safety
The medieval walled city of Carcassonne in France is built upon high ground to provide maximum protection from attackers.
Historically within the Middle East, Europe and the rest of the Old World settlements were located on higher ground (for defense) and close to fresh water sources[citation needed]. Cities have often grown onto coastal and flood plains at risk of floods and storm surges. Urban planners must consider these threats. If the dangers can be localised then the affected regions can be made into parkland or Greenbelt, often with the added benefit of open space provision.
Extreme weather, flood, or other emergencies can often be greatly mitigated with secure emergency evacuation routes and emergency operations centres. These are relatively inexpensive and unintrusive, and many consider them a reasonable precaution for any urban space. Many cities will also have planned, built safety features, such as levees, retaining walls, and shelters.
In recent years, practitioners have also been expected to maximize the accessibility of an area to people with different abilities, practicing 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 pleasant.
City planning tries to control criminality with structures designed from theories such as socio-architecture or environmental determinism. These theories say that an urban environment can influence individuals' obedience to social rules. The theories often say that psychological 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.
Oscar Newman’s defensible space theory cites the modernist housing projects of the 1960s as an example of environmental determinism, where large blocks of flats are surrounded by shared and disassociated public areas, which are hard for residents to identify with. As those on lower incomes cannot hire others to maintain public space such as security guards or grounds keepers, and because no individual feels personally responsible, there was a general deterioration of public space leading to a sense of alienation and social disorder Source
Jane Jacobs is another notable environmental determinist and is associated with the "eyes on the street" concept. By improving ‘natural surveillance’ of shared land and facilities of nearby residents by literally increasing the number of people who can see it, and increasing the familiarity of residents, as a collective, residents can more easily detect undesirable or criminal behaviour.
The "broken-windows" theory argues that small indicators of neglect, such as broken windows and unkempt lawns, promote a feeling that an area is in a state of decay. Anticipating decay, people likewise fail to maintain their own properties. The theory suggests that abandonment causes crime, rather than crime causing abandonment[citation needed].
Some planning methods might help an elite group to control ordinary citizens. Haussmann's renovation of Paris created a system of wide boulevards which prevented the construction of barricades in the streets and eased the movement of military troops. In Rome, the Fascists in the 1930s created ex novo many new suburbs in order to concentrate criminals and poorer classes away from the elegant town.
Other social theories point out that in Britain 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 rationalize the outcomes of a free (relatively unregulated) market.
Slums
Main article: Slums
The rapid urbanization of the last century has resulted in a significant amount of slum habitation in the major cities of the world, particularly in the Third World. There is significant demand for planning resources and strategies to address the issues that arise from slum development, and many planning theorists and practitioners are calling for increased attention and resources in this area, particularly the Commonwealth Association of Planners. When urban planners give their attention to slums, one also have to pay attention to the racial make - up of that area to ensure that racial steering does not occur.
The issue of slum habitation has often been resolved via a simple policy of clearance, however more creative solutions are beginning to emerge such as Nairobi's "Camp of Fire" program, where established slum-dwellers have promised to build proper houses, schools, and community centers without any government money, in return for land they have been illegally squatting on for 30 years. The "Camp of Fire" program is one of many similar projects initiated by Slum Dwellers International, which has programs in Africa, Asia, and South America.
Urban decay
Main article: Urban decay
Broken Promises:John Fekner © 1980 Charlotte Street Stencils South Bronx, New York. Jimmy Carter and Ronald Reagan both came to this spot during their political careers to make promises.
Urban decay is a process by which a city, or a part of a city, falls into a state of disrepair. It is characterized by depopulation, property abandonment, high unemployment, fragmented families, political disenfranchisement, crime, and desolate and unfriendly urban landscapes.
Urban decay was associated with Western cities, especially North America and parts of Europe during the 1970s and 1980s. During this time period major changes in global economies, transportation, and government policies created conditions that fostered urban decay.
The effects of urban decay run counter to the development patterns found in most cities in Europe and countries outside of North America, where slums are usually located on the outskirts of major metropolitan areas while the city center and inner city retain high real estate values and a steady or increasing population. In contrast, North American cities often experienced an outflux of population to city suburbs or exurbs, as in the case of white flight.
There is no single cause of urban decay, though it may be triggered by a combination of interrelated factors, including urban planning decisions, the development of freeways, suburbanisation, redlining, immigration restrictions and racial discrimination.
Reconstruction and renewal
Main article: Urban Renewal
The overall area plan for the reconstruction of Kabul's Old City area, the proposed Kabul - City of Light Development.
Areas devastated by war or invasion represent a unique challenge to urban planners: the area of development is not one for simple modification, nor is it a "blank slate". Buildings, roads, services and basic infrastructure like power, water and sewerage are often severely compromised and need to be evaluated to determine what, if anything, can be salvaged for re-incorporation. There is also the problem of population; more often than not, people are also still living in these areas, displaced but not removed, and their issues need to be addressed. Historic areas and religious or social centers also need to be preserved and re-integrated into the new city plan. A prime example of this is the capital city of Kabul, Afghanistan, which after decades of civil war and occupation has regions that have literally been reduced to rubble. Despite this, the indigenous population continues to live in the area, constructing makeshift homes and shops out of whatever can be salvaged. Any reconstruction plan proposed, such as Hisham Ashkouri's City of Light Development, needs to be sensitive to the needs of this community and its existing culture, businesses and needs.
Urban Reconstruction Development plans must also work with government agencies as well as private interests to develop workable designs.
Transport
Main article: Transportation Planning
Very densely built-up areas require high capacity urban transit, urban planners must consider these factors in long term plans.
Although an important factor, there is a complex relationship between urban densities and car use.
There is a direct, well-researched connection between the density of an urban environment, and the need to travel within it[citation needed]. Good quality transport is often followed by development. Development beyond a certain density can quickly overcrowd transport[citation needed].
Good planning attempts to place higher densities of jobs or residents near high-volume transportation. For example, some cities permit commerce and multi-story apartment buildings only within one block of train stations and four-lane boulevards, and accept single-family dwellings and parks further away[citation needed].
Densities can be measured in several ways[citation needed]. A common method, used is the Floor area ratio, using the floor area of buildings divided by the land area. Ratios below 1.5 could be considered low density, and plot ratios above five very high density. Most exurbs are below two, while most city centres 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.
City authorities may try to encourage lower densities to reduce infrastructure costs, though some observers note that low densities may not accommodate enough population to provide adequate demand or funding for that infrastructure. In the UK, recent years have seen a concerted effort to increase the density of residential development in order to better achieve sustainable development. Increasing development density has the advantage of making mass transport systems, district heating and other community facilities (schools, health centres, etc) more viable. However critics of this approach dub the densification of development as 'town cramming' and claim that it lowers quality of life and restricts market led choice[citation needed].
Problems can often occur at residential densities between about two and five[citation needed]. These densities can cause traffic jams for automobiles, yet are too low to be commercially served by trains or light rail systems. The conventional solution is to use buses, but these and light rail systems may fail where automobiles and excess road network capacity are both available, achieving less than 1% ridership[citation needed].
The Lewis-Mogridge Position claims that increasing road space is not an effective way of relieving traffic jams as latent or induced demand invariably emerges to restore a socially-tolerable level of congestion.
Some theoreticians[citation needed] speculate that personal rapid transit (PRT) might coax people from their automobiles, and yet effectively serve intermediate densities, but this has not been demonstrated.
Addressing
If house numbering is part of the plan, the risk that the numbering task will end up in the hands of non-professionals can be reduced, saving citizens much lost time looking for addresses later. This is especially important for non grid plan areas with no city-wide addressing standard already in place. Unfortunately addressing is often not even mentioned in urban planning courses.
Suburbanization
Main article: Suburbanization
Very low (auto-oriented) density suburban development near Cincinnati, Ohio, United States
In some countries declining satisfaction with the urban environment is held to blame for continuing migration to smaller towns and rural areas (so-called urban exodus). Successful urban planning supported Regional planning can bring benefits to a much larger hinterland or city region and help to reduce both congestion along transport routes and the wastage of energy implied by excessive commuting. Urban scholar N.J. Slabbert claims that the advent of the Internet has opened the way to "telecommunities" or populations of workers who will no longer commute physically, and that this will greatly revitalize small towns in the 21st century.
Environmental factors
Main article: Environmental planning
Environmental protection and conservation are of utmost importance to many planning systems across the world. Not only are the specific effects of development to be mitigated, but attempts are made to minimise the overall effect of development on the local and global environment. This is commonly done through the assessment of Sustainable urban infrastructure. In Europe this process is known as Sustainability Appraisal.
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[citation needed].
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. A common form of planning that leads to suburban sprawl is single use zoning.
An urban planner is likely to use a number of Quantitative tools to forecast impacts of development on a variety of environmental concerns including roadway air dispersion models to predict air quality impacts of urban highways and roadway noise models to predict noise pollution effects of urban highways. As early as the 1960s, noise pollution was addressed in the design of urban highways as well as noise barriers. The Phase I Environmental Site Assessment can be an important tool to the urban planner by identifying early in the planning process any geographic areas or parcels which have toxic constraints.
Process
Blight may sometimes impulse communities into redeveloping and urban planning.
The traditional planning process focused on top-down processes where the town planner created the plans. A planner is usually skilled in either surveying, engineering or architecture, bringing to the town planning process ideals based around these disciplines. They typically worked for national or local governments.[citation needed]
Changes to the planning process over past decades have witnessed the metamorphosis of the role of the urban planner in the planning process. Calls championing for more democratic planning processes have played a huge role in allowing the public to make important decisions as part of the planning process. Community organizers and social workers are now very involved in planning from the grassroots level
Developers too have played huge roles in influencing the way development occurs, particularly through project-based planning. Many recent developments were results of large and small-scale developers who purchased land, designed the district and constructed the development from scratch. The Melbourne Docklands, for example, was largely an initiative pushed by private developers who sought to redevelop the waterfront into a high-end residential and commercial district.
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Posted by Ismail Hidayat at 10:24 AM | 0 comments
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