Topic: Urban studies and planning

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Arcosanti

United States Architecture Urban studies and planning United States/Arizona

Arcosanti is a projected experimental town with a molten bronze bell casting business in Yavapai County, central Arizona, 70 mi (110 km) north of Phoenix, at an elevation of 3,732 feet (1,130 meters). Its arcology concept was posited by the Italian-American architect, Paolo Soleri (1919–2013). He began construction in 1970, to demonstrate how urban conditions could be improved while minimizing the destructive impact on the earth. He taught and influenced generations of architects and urban designers who studied and worked with him there to build the proposed "town".

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Bastion Fort

Military history Military history/Military science, technology, and theory Architecture Urban studies and planning Military history/Fortifications Civil engineering Engineering

A bastion fort or trace italienne (a phrase improperly derived from French, literally meaning Italian outline), is a fortification in a style that evolved during the early modern period of gunpowder when the cannon came to dominate the battlefield. It was first seen in the mid-15th century in Italy. Some types, especially when combined with ravelins and other outworks, resembled the related star fort of the same era.

The design of the fort is normally a polygon with bastions at the corners of the walls. These outcroppings eliminated protected blind spots, called "dead zones", and allowed fire along the curtain from positions protected from direct fire. Many bastion forts also feature cavaliers, which are raised secondary structures based entirely inside the primary structure.

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Braess’s paradox

Mathematics Economics Politics Urban studies and planning Organizations Game theory

Braess' paradox is the observation that adding one or more roads to a road network can slow down overall traffic flow through it. The paradox was postulated in 1968 by German mathematician Dietrich Braess, who noticed that adding a road to a particular congested road traffic network would increase overall journey time.

The paradox may have analogies in electrical power grids and biological systems. It has been suggested that in theory, the improvement of a malfunctioning network could be accomplished by removing certain parts of it. The paradox has been used to explain instances of improved traffic flow when existing major roads are closed.

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Company town

Business Urban studies and planning Cities

A company town is a place where practically all stores and housing are owned by the one company that is also the main employer. Company towns are often planned with a suite of amenities such as stores, houses of worship, schools, markets and recreation facilities. They are usually bigger than a model village ("model" in the sense of an ideal to be emulated).

Some company towns have had high ideals, but many have been regarded as controlling and/or exploitative. Others developed more or less in unplanned fashion, such as Summit Hill, Pennsylvania, United States, one of the oldest, which began as an LC&N Co. mining camp and mine site nine miles (14.5 km) from the nearest outside road.

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Ha-ha wall

Urban studies and planning Horticulture and Gardening

A ha-ha (French: hâ-hâ or saut de loup) is a recessed landscape design element that creates a vertical barrier while preserving an uninterrupted view of the landscape beyond.

The design includes a turfed incline that slopes downward to a sharply vertical face (typically a masonry retaining wall). Ha-has are used in landscape design to prevent access to a garden, for example by grazing livestock, without obstructing views. In security design, the element is used to deter vehicular access to a site while minimizing visual obstruction.

The name "ha-ha" is thought to have stemmed from the exclamations of surprise by those coming across them, as the walls were intentionally designed so as not to be visible on the plane of the landscape.

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Kowloon Walled City

Military history China Urban studies and planning Military history/Fortifications Military history/Asian military history Hong Kong Military history/Chinese military history Organized crime

Kowloon Walled City was an ungoverned, densely populated settlement in Kowloon City, Hong Kong. Originally a Chinese military fort, the Walled City became an enclave after the New Territories were leased to the UK by China in 1898. Its population increased dramatically following the Japanese occupation of Hong Kong during World War II. By 1990, the walled city contained 50,000 residents within its 2.6-hectare (6.4-acre) borders. From the 1950s to the 1970s, it was controlled by local triads and had high rates of prostitution, gambling, and drug abuse.

In January 1987, the Hong Kong municipal government announced plans to demolish the walled city. After an arduous eviction process, demolition began in March 1993 and was completed in April 1994. Kowloon Walled City Park opened in December 1995 and occupies the area of the former Walled City. Some historical artefacts from the walled city, including its yamen building and remnants of its southern gate, have been preserved there.

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Lewis-Mogridge Position

Urban studies and planning

The Lewis–Mogridge position, named after David Lewis and Martin J. H. Mogridge, was formulated in 1990 and observes that as more roads are built, more traffic consequently fills these roads. Speed gains from some new roads can disappear within months, if not weeks. Sometimes, new roads help to reduce traffic jams, but in most cases, the congestion is only shifted to another junction.

The position reads traffic expands to meet the available road space (Mogridge, 1990). It is generally referred to as induced demand in the transport literature, and was posited as the "Iron Law of Congestion" by Anthony Downs. It is a special case of Jevons paradox (where the resource in question is traffic capacity), and relates to the Marchetti's constant (average commute times are similar in widely varying conditions).

Following the position, it is not generally concluded that new roads are never justified but that their development needs to consider the whole traffic system, which means understanding the movement of goods and people in detail as well as the motivation behind the movement.

The position is often used to understand problems caused by private transport such as congested roads in cities and on motorways. It can also be used to explain the success of schemes such as the London congestion charge.

The position, however, is not confined to private transport. Mogridge, a British transport researcher, concluded also that all road investment in a congested urban area will have the effect of reducing the average speed of the transport system as a whole: road and public transport. The relationship and overall equilibria are also known as the "Downs–Thomson paradox". However, according to Downs, the link between average speeds on public transport and private transport applies only "to regions in which the vast majority of peak-hour commuting is done on rapid transit systems with separate rights of way. Central London is an example, since in 2001 around 85 percent of all morning peak-period commuters into that area used public transit (including 77 percent on separate rights of way) and only 11 percent used private cars. When peak-hour travel equilibrium has been reached between the subway system and the major commuting roads, then the travel time required for any given trip is roughly equal on both modes."

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Manhole cover thought to be propelled into space

Transport Urban studies and planning Engineering

A manhole cover or maintenance hole cover is a removable plate forming the lid over the opening of a manhole, an opening large enough for a person to pass through that is used as an access point for an underground vault or pipe. It is designed to prevent anyone or anything from falling in, and to keep out unauthorized persons and material.

Manhole covers date back at least to the era of ancient Rome, which had sewer grates made from stone.

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Marchetti's constant

Urban studies and planning

Marchetti's constant is the average time spent by a person for commuting each day, which is approximately one hour. It is named after Italian physicist Cesare Marchetti, though Marchetti himself attributed the "one hour" finding to transportation analyst and engineer Yacov Zahavi. Marchetti posits that although forms of urban planning and transport may change, and although some live in villages and others in cities, people gradually adjust their lives to their conditions (including location of their homes relative to their workplace) such that the average travel time stays approximately constant. Ever since Neolithic times, people have kept the average time spent per day for travel the same, even though the distance may increase due to the advancements in the means of transportation. In his 1934 book Technics and Civilization, Lewis Mumford attributes this observation to Bertrand Russell:

Mr. Bertrand Russell has noted that each improvement in locomotion has increased the area over which people are compelled to move: so that a person who would have had to spend half an hour to walk to work a century ago must still spend half an hour to reach his destination, because the contrivance that would have enabled him to save time had he remained in his original situation now—by driving him to a more distant residential area—effectually cancels out the gain.

A related concept is that of Zahavi, who also noticed that people seem to have a constant "travel time budget", that is, "a stable daily amount of time that people make available for travel." David Metz, former chief scientist at the Department of Transport, UK, cites data of average travel time in Britain drawn from the British National Travel Survey in support of Marchetti's and Zahavi's conclusions. The work casts doubt on the contention that investment in infrastructure saves travel time. Instead, it appears from Metz's figures that people invest travel time saved in travelling a longer distance, a particular example of Jevons paradox described by the Lewis–Mogridge position. Because of the constancy of travel times as well as induced travel, Robert Cervero has argued that the World Bank and other international aid agencies evaluate transportation investment proposals in developing and rapidly motorizing cities less on the basis of potential travel-time savings and more on the accessibility benefits they confer.

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New Urbanism

History Architecture Sociology Urban studies and planning

New Urbanism is an urban design movement which promotes environmentally friendly habits by creating walkable neighborhoods containing a wide range of housing and job types. It arose in the United States in the early 1980s, and has gradually influenced many aspects of real estate development, urban planning, and municipal land-use strategies. New urbanism attempts to address the ills associated with urban sprawl and post-Second World War suburban development.

New Urbanism is strongly influenced by urban design practices that were prominent until the rise of the automobile prior to World War II; it encompasses ten basic principles such as traditional neighborhood design (TND) and transit-oriented development (TOD). These ideas can all be circled back to two concepts: building a sense of community and the development of ecological practices.

The organizing body for New Urbanism is the Congress for the New Urbanism, founded in 1993. Its foundational text is the Charter of the New Urbanism, which begins:

We advocate the restructuring of public policy and development practices to support the following principles: neighborhoods should be diverse in use and population; communities should be designed for the pedestrian and transit as well as the car; cities and towns should be shaped by physically defined and universally accessible public spaces and community institutions; urban places should be framed by architecture and landscape design that celebrate local history, climate, ecology, and building practice.

New Urbanists support regional planning for open space; context-appropriate architecture and planning; adequate provision of infrastructure such as sporting facilities, libraries and community centres; and the balanced development of jobs and housing. They believe their strategies can reduce traffic congestion by encouraging the population to ride bikes, walk, or take the train. They also hope that this set up will increase the supply of affordable housing and rein in suburban sprawl. The Charter of the New Urbanism also covers issues such as historic preservation, safe streets, green building, and the re-development of brownfield land. The ten Principles of Intelligent Urbanism also phrase guidelines for new urbanist approaches.

Architecturally, new urbanist developments are often accompanied by New Classical, postmodern, or vernacular styles, although that is not always the case.

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