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.
The successful practice of urban planning might imply notions of character, of "home" and "sense of place", local identity, respect for natural, artistic and heritage features, an understanding of the "urban grain" or "townscape", and concern for the permeability of an area by pedestrians.
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. 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.
In ancient times, Romans used a consolidated scheme for city planning, mainly developed after the primary need of a military defensive organisation. Effectively, many European towns still preserve the essence of these schemes, like happens notably in Turin.
Planning and safety Some interventions or some forms of distribution of different classes of buidings have been interpreted in the sense that urban planning could have sometimes been used to facilitate the control of citizens by an elite. 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.
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.
On city planning and criminality[?], it may be observed that theories generally included in the so-called socio-architecture[?], like environmental determinism, stress that the specific urban environment has a capacity to influence individuals' behaviour and their acceptance of social rules. It is asserted that in more densely developed areas, crimes and the use of illegal drugs would be relatively common, because of the detrimental effect of mean, uncaring functionalism (of both aesthetical look and practical distribution of spaces in poorer zones), or because of an insufficient availability of individual space, that would cause a continuous psychological pressure.
Other theories, more on a social view, point out that, starting from English 18th century and notably in most countries more recently, the transformation of societies from rural agriculture to industrial systems caused a difficult adaptation to urban living and underline that prevalent planning policies ignore these tensions, forcing individuals to live in a condition of perpetual extraneity to his context, therefore lacking a necessary psychological comfort of feeling "at home" when at home. Often these theorists seek a reconsideration of commonly used "standards" that may simply attempt to 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.
Densities are usually measured as the floor area of buildings divided by the land area. Ratios below 1.5 are low density. Ratios above 5 are very high density. Most exurbs are below 2, while most city centers are well above 5. Walk-up apartments with basement garages can easily achieve a density of 3. Skyscrapers easily achieve densities of 30 or more. Higher densities tempt developers with higher profits. Cities try to lower densities to reduce infrastructure costs.
Automobiles are well suited to low-density developments, and serve densities as high as 1.5 with basic limited-access highways. In southern California a pair of "car-pool lanes" can carry as many passenger miles as an extra four-lane highway on the same route. A car-pool lane is a separated lane in which vehicles must carry multiple riders. In Singapore, taxes on peak use times have reduced congestion. Motorists paying the taxes get special windshield stickers. These innovations may get automobiles to densities as high as 2.5.
The problem is that there is a no-mans-land of densities between about 2 and 5 that cause 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 are spurned by automobile users as inconvienient. Some persons speculate that personal rapid transit might coax people from their automobiles, and yet effectively serve intermediate densities, but this has not been demonstrated. Light rail systems normally fail when automobiles are available, achieving less than 1% ridership, with no practical effect on development.
Densities above 5 are well-served by railed transit systems. Most such areas were actually developed in response to railed transit systems in the middle 1800s, and have large historical riderships that have never used automobiles.
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.
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 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.
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.