City block

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For other uses, see City block (disambiguation).
Diagram of an example of a rectangular city block as seen from above, surrounded by streets. The block is divided into lots which were numbered by the developer as shown in red here and as shown in plats. The addresses on this example 800 block are shown in black and the adjacent blocks are the 700 and 900 blocks. An alley shown in light gray runs lengthwise down the middle of the block. Streets are shown in dark gray. Sidewalks are shown in light gray. Parkways are shown in green with walkways shown in light gray from every lot to the street.
Diagram of an example of a rectangular city block as seen from above, surrounded by streets. The block is divided into lots which were numbered by the developer as shown in red here and as shown in plats. The addresses on this example 800 block are shown in black and the adjacent blocks are the 700 and 900 blocks. An alley shown in light gray runs lengthwise down the middle of the block. Streets are shown in dark gray. Sidewalks are shown in light gray. Parkways are shown in green with walkways shown in light gray from every lot to the street.
Chicago in 1857. Blocks of 80, 40, and 10 acres establish a street grid at the outskirts which continues into the more finely divided downtown area.
Chicago in 1857. Blocks of 80, 40, and 10 acres establish a street grid at the outskirts which continues into the more finely divided downtown area.

A city block, urban block or simply block is a central element of urban planning and urban design. A city block is the smallest area that is surrounded by streets. City blocks are the space for buildings within the street pattern of a city, they form the basic unit of a city's urban fabric. City blocks may be subdivided into any number of smaller lots or parcels of land usually in private ownership, though in some cases, it may be other forms of tenure. City blocks are usually built-up to varying degrees and thus form the physical containers or 'streetwalls' of public space. Most cities are composed of a greater or lesser variety of sizes and shapes of urban block. For example, many pre-industrial cores of cities in Europe, Asia and the Middle-east tend to have irregularly shaped street patterns and urban blocks, while cities based on grids have much more regular arrangements.

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[edit] Grid plan

In most cities of the world that were planned, rather than developing gradually over a long period of time, streets are typically laid out on a grid plan, so that city blocks are square or rectangular. Using the perimeter block development principle, city blocks are developed so that buildings are located along the perimeter of the block, with entrances facing the street, and semi-private courtyards in the rear of the buildings.[1] This arrangement is intended to provide good social interaction among people.[1]

Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is impossible to generalize about the size of a city block. However, as reference points, the standard block in Manhattan is about 264 by 900 feet (80 m × 274 m); and in some U.S. cities standard blocks are as wide as 660 feet (200 m). While for example, the city blocks in the central city grid of Melbourne, Australia are 200 by 100 metres (660 ft × 330 ft).

In most areas, cities have grown in a more amorphous manner rather than being planned from the outset. For this reason, an even pattern of square or rectangular city blocks is very uncommon in much of Europe. Following the example of Philadelphia, New York City adopted the Commissioners' Plan of 1811 for a more extensive grid plan. In much of the United States and Canada, the addressing systems follow a block and lot number system, in which each block of a street is allotted 100 building numbers.

[edit] Superblock

Superblocks were popular during the early and mid-20th century, arising from modernist ideas in architecture and urban planning. A superblock is much larger than a traditional city block, with greater setback for buildings, and is typically bounded by widely spaced, high-speed, arterial or circulating routes rather than by local streets. Superblocks are generally associated with suburbs, planned cities, and the urban renewal of the mid-20th century; that is, in areas in which a street hierarchy has replaced the traditional grid. In a residential area of a suburb, the interior of the superblock is typically served by cul-de-sac roads.

Urban planner Clarence Perry argued for use of superblocks and related ideas in his "neighborhood unit" plan, which aimed to organize space in a way that is more pedestrian-friendly and provided open plazas and other space for residents to socialize.[2] In the 1930s, superblocks were often used in urban renewal public housing projects in American cities.[3] In using superblocks, housing projects aimed to eliminate back alleys, which were often associated with slum conditions.[3]

Superblocks are also used when functional units such as rail yards or housing projects are too big to fit in one block.

[edit] Perimeter block

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A perimeter block is a type of city block which is built up on all sides surrounding a central space that is semi-private. They are usually between 4 and 7 storeys in height, and may contain a mixture of uses, with commercial or retail functions on the ground floor. Perimeter blocks are a key component of many European cities and are an urban form that allows very high urban densities to be achieved without high-rise buildings.

[edit] See also

[edit] References

  1. ^ a b Frey, Hildebrand Frey (1999). Designing the City: Towards a More Sustainable Urban Form. E & FN Spon. 
  2. ^ Keating, W. Dennis, Norman Krumholz (2000). "Neighborhood Planning". Journal of Planning Education and Research 20(1): p. 111-114. 
  3. ^ a b Ben-Joseph, Eran, Terry S. Szold (2005). Regulating Place: Standards and the Shaping of Urban America. Routledge. 

[edit] Further reading

  • Jacobs, J (1961) The death and life of great American cities