A city block, residential 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, and form the basic unit of a city's urban fabric. City blocks may be subdivided into any number of smaller land lots 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.
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.This arrangement is intended to provide good social interaction among people.
Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is difficult to generalize about the size of a city block. Oblong blocks range considerably in width and length. The standard block in Manhattan is about 264 by 900 feet (80 m × 274 m). In Chicago, a typical city block is 660 by 330 feet (200 m × 100 m) (w × h), meaning that 16 east-west blocks or 8 north-south blocks measure one mile, which has been adopted by other US cities. The blocks in central Melbourne, Australia, are also 330 by 660 feet (100 m × 200 m), formed by splitting the square blocks in an original grid with a narrow street down the middle.
Many world cities have grown by accretion over time rather than being planned from the outset. For this reason, a regular pattern of even, square or rectangular city blocks is not so common among European cities, for example. An exception is represented by those cities that were founded as Roman military settlements, and that often preserve the original grid layout around two main orthogonal axes. One notable example is Turin, Italy. Following the example of Philadelphia, New York City adopted the Commissioners' Plan of 1811 for a more extensive grid plan. By the middle of the 20th century, the adoption of the uniform, rectilinear block subsided almost completely, and different layouts prevailed, with random sized and either curvilinear or non-orthogonal blocks and corresponding street patterns.
In much of the United States and Canada, the addresses follow a block and lot number system, in which each block of a street is allotted 100 building numbers.
The concept of city block can be generalized as a superblock or sub-block.
A superblock or super-block is an area of urban land bounded by arterial roads that is the size of multiple typically-sized city blocks. Within the superblock, the local road network, if any, is designed to serve local needs only.
Within the broad concept of a superblock, various typologies emerge based primarily on the internal road networks within the superblock, their historical context, and whether they are auto-centric or pedestrian-centric. The context in which superblocks are being studied or conceived gives rise to varying definitions.
An internal road network characterised by cul-de-sacs is typical of auto-centric suburban development primarily in Western countries throughout the 20th century. The Oxford Dictionary of Architecture and Landscape Architecture's definition is rooted within this typically suburban conception:
“Area containing residential accommodation, shops, schools, offices, etc., with public open space (e.g. a green), surrounded by roads and penetrated by cul-de-sac service-roads. It is linked to other super-blocks and a town centre by means of paths over or under the roads (e.g. in Radburn planning).”
Though the aim of such superblocks is generally to minimise traffic within the superblock by directing it to arterial roads, the effect in many cases has been to entrench automobile dependence by limiting pedestrian permeability.
Superblocks can also contain an orthogonal internal road network, including ones based on a grid plan or quasi-grid plan. This typology is prevalent in Japan and China, for example. Chen defines the supergrid and superblock urban morphology in this context as follows:
“The Supergrid is a large-scale net of wide roads that defines a series of cells or Superblocks, each containing a network of narrower streets.”
Superblocks can also be retroactively superimposed on pre-existing grid plan by changing the traffic rules and streetscape of internal streets within the superblock, as in the case of Barcelona’s superilles (Catalan for superblocks). Each superilla comprises nine city blocks, with speed limits on the internal roads slowed to 10–20 km/h and through traffic disallowed, with through travel only possible on the perimeter roads.
Superblocks were popular during the early and mid-20th century auto-centric suburban development, arising from modernist ideas in architecture and urban planning. Planning in this era was based upon the distance and speed scales for the automobile and discounted the pedestrian and cyclist modes, as obsolete transportation vehicles.[ citation needed ] A superblock is much larger than a traditional city block, with a greater setback for buildings, and is typically bounded by widely spaced, high-speed, arterial or circulating routes rather than by local streets. Superblocks are often found in suburbs or planned cities, or are the result of urban renewal of the mid-20th century, where a street hierarchy has replaced the traditional grid. In a residential area of a suburb, the interior of the superblock is typically served by dead-ended or looped streets. The discontinuous streets served the automobile as longer distances, and the extra fuel required to go between destinations, was not a concern, but at the pedestrian scale, the discontinuity of the roads added to the distance that must be traveled. The discontinuity inside the superblock forced car dependency, discouraged errand walking, and forced more traffic onto the fewer continuous streets, increasing demand for through streets, which led ultimately to these streets having more travel lanes added for cars, thereby making it more difficult for any pedestrian to cross such streets. In this way, superblocks cut up the city into isolated units, expanded automobile dominance, and made it impossible for pedestrians and cyclists to get anywhere outside of the superblock. Superblocks can also be found in central city areas, where they are more often associated with institutional, educational, recreational and corporate rather than residential uses.
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 was more "pedestrian-friendly" and provided open plazas and other space for residents to socialize. Planners, today, now know that the street discontinuity and the multi-lane roads associated with superblocks have caused the decline of pedestrian and bicycle use every where this "sprawl" pattern is present. The traditional urban block diffused automobile traffic onto several narrower roads at slower speeds. This more finely connected network of narrower roads better allowed the pedestrian and cyclist realms to flourish. The superblock, at the scale only suitable for automobiles, and not pedestrians, was the means for ultimate automobile dominance by the end of the 20th century.The same intention to facilitate pedestrian movement and socializing is captured by an influential 1989 conceptual design of a Pedestrian Pocket (see diagram). It is, similarly, a superblock composed of nine normal city blocks clustered around a light rail station and a central open space. Its circulation pattern consists primarily of a dense pedestrian network which is complementary to but independent from the car network. Access by car is provided by means of three loops. This superblock differs from Perry's concept in that it makes it impossible for cars to traverse it rather than very difficult; it is car-impermeable.
In the 1930s, superblocks were often used in urban renewal public housing projects in American cities.In using superblocks, housing projects aimed to eliminate back alleys, which were often associated with slum conditions.
Superblocks are also used when functional units such as rail yards or shipyards, inherited from the 19th and early 20th centuries, are too big to fit in an average city block. A contemporary function which reflects ancient practices that also requires larger than typical blocks is the sports stadium or arena. Just as the Colosseum in ancient Rome, sports complexes require superblocks. The Providence Park stadium in Portland, for example, takes up four normal city blocks as does the equally large Greensboro Coliseum in North Carolina. Other contemporary institutions, establishments or functions that use superblocks are: city halls like Government Center, Boston and Toronto City Hall; regional general hospitals or specialized medical centres; convention and exhibition centers, such as Exhibition Place in Toronto and the Boston Convention and Exhibition Center; and downtown enclosed Shopping Malls such as Eaton Centre in Toronto, echoing the large gallerias of the 19th century. Cultural complexes, such as the Lincoln Center in New York City, often occupy a superblock achieved through the consolidation of regular city blocks. A recent[ when? ] superblock user is the merchandise distribution centre, which can range in area from one to ten city blocks.
Most notably, however, the largest superblocks in contemporary cities are used by university and college campuses[ citation needed ] such as Massachusetts Institute of Technology, the University of Illinois at Chicago, the City College of New York, Columbia University and the University of Alberta in Edmonton. The "campus" impact on the city block structure is quite prominent particularly in small university towns such as Waterloo, Ontario or Ithaca, New York where the university superblock counts for a sizeable portion of the total city area. Campuses, in general, are fully walkable and sociable environments within the superblock structure. On some university campuses the extensive and exclusive pedestrian path network at grade is supplemented with below grade paths. New Urbanists would argue that separating circulation modes effectively kills the social interaction that bolsters urban areas.[ citation needed ]
Additional users of the superblock concept are large national or multinational corporations who constructed campuses in the late 1900s and 2000s. Examples of superblock campuses include Google in Mountain View, California; and Apple and Hewlett-Packard in San Jose, California. Another well-known commercial superblock is the World Trade Center site in New York City, where several streets of Manhattan's downtown grid were removed and de-mapped to make room for the center.
Social and housing agencies in the U.S., Canada and the UK used the superblock model for large housing projects such as Regent Park in Toronto and Benny Farm in Montreal, Canada. In New York City, the Stuyvesant Town private market, residential development superblock takes up about 18 normal city blocks and provides a large green amenity for its residents and neighbours. It uses crescent (loop) rather than dead-ended streets inside the superblock and an extensive network of paths that provide excellent connectivity within the block and to the neighbouring areas (see drawing).
Where the superblock is used for housing projects like Stuyvesant Town, the advantages sought are an improved separation of vehicular and pedestrian circulation, enhanced tranquility and reduced accident risk within the neighbourhood. In 2003, Vauban (a rail suburb of Freiburg, Germany) was constructed with similar goals.Its layout consists mainly of a superblock with a central pedestrian spine and a few narrow looped and dead-ended streets. The British new town of Milton Keynes is built around a grid of one-kilometre square superblocks (see drawing).
Superblocks have been proposed as a potential solution to road space prioritisation and increased pedestrian flows in the CBD of Melbourne, Australia. The City of Melbourne's 2018 Transport Discussion Paper: City Space suggests, based on the example of Barcelona's superilles, that “‘Superblocks’ could be applied in Melbourne to make streets in the central city safer, greener, more inclusive and more vibrant.”
The superblock concept has been applied retroactively in Barcelona's La Ribera and Gràcia districts, which both have a medieval street network with narrow and irregular streets, since 1993. In these two cases it resulted in an increase of journeys on foot (over 10%) and by bicycle (>15%) and in a higher level of commercial and service activity.
Superblocks, or super·illes in the native Catalan, are now being superimposed in the Eixample District's famous Ildefons Cerdà-designed late 19th century grid plan. km/h initially. It was estimated that this could be implemented city-wide for less than €20 million, simply by changing traffic signals.Each superilla comprises nine city blocks, or illes, in which the internal traffic flows have been altered to disallow through traffic, and speed limits on internal roads reduced. After entering a superilla from a perimeter road, vehicles are only able to circumnavigate one city block and return out to the same perimeter road again, meaning that local access to garages and businesses is maintained, but making it impossible to cut through to the other side. Speed limits have also been reduced to 20
It is planned to further reduce speeds to 10 km/h and remove on-street parking by building more off-street car parks. This is intended to make the internal streets safer for pedestrians and create more space for playing games, sports, and cultural activities such as outdoor cinemas.
The concept was initially spurred by a redesign of the city's bus network that consolidated bus routes into a simpler orthogonal network, with more frequent services.With many streets freed from buses as a result, and the idea was formulated to create the superilles in order to reduce traffic, cut the high levels of air and noise pollution in the city, and reallocate space to pedestrians and cyclists. The superilles have been met with criticism and resistance from some residents however, who have complained about the dramatically increased distance for some previously short car trips, and the increased traffic on the arterial perimeter roads.
Superblocks have been the prevalent mode of urban land use planning in Japan, even being described as the " sine qua non of Japanese urban design",present in all medium to large Japanese cities to a greater or lesser degree. Cities are typically arranged around a system of wide arterial roads, often approximating a grid and flanked by generous sidewalks, and an orthogonal network of narrow internal streets, normally operating as shared zones with no sidewalks. The grid plan layout of Japanese cities such as Kyoto and Nara dates back to the eighth century, which were in turn derived from Chinese grid models. The system of superblocks were created mostly in the early to mid 20th century by physically widening arterial roads, superimposing the supergrid and superblock structure in a physical sense. This contrasts with the Barcelona model wherein the superblock model was imposed through changed traffic signalling rather than physical street widening. They further contrast to Western auto-centric models described above as they are typically characterised by highly walkable and cycle-able street networks, featuring high-density mixed use development and supported by highly effective and efficient public transport systems.
Resulting largely from planning controls which link building height with street width, Japanese superblocks are typically characterised by a ‘hard shell’ of tall buildings with commercial uses along the perimeter arterial roads, with a ‘soft yolk’ of low-rise residential use in the centre.
The spatial structure of superblocks can also be analysed, per a taxonomy detailed by Barrie Shelton,through the classification of roads as ‘global’, being the arterial roads which provide for cross-city travel, ‘local’ roads, which provide local access to buildings within the superblock, and ‘glocal’ roads, which may cross the entire superblock, allowing through travel, and in many instances into neighbouring superblocks. Glocal roads differ from global roads however, in that they are narrow, have lower speed limits, and do not form part of the ‘supergrid’ structure. Shelton also describes the sidewalks of the global arterial roads as functioning as streets in themselves, or ‘sidewalk streets’, operating in a similar manner to the local streets.
In a geoprocessing perspective there are two complementary ways of modeling city blocks:
Always a block without sidewalks is within a block with sidewalks. The geometric subtraction of a block without sidewalks from block with sidewalks, contains the sidewalk, the alley, and any other non-lot sub-structure.
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 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.
In North American English and Australian English, the word "block" is used as an informal unit of distance.For example, someone giving directions might say, "It's three blocks from here".
There have been online innovations and websites such as msnbc.com-owned EveryBlock, which uses geo-specific feeds from neighborhood blogs, Flickr, Yelp, Craigslist, YouTube, Twitter, Facebook and other aggregated data to give readers a picture of what is going on in their town or neighborhood down to the block.
The grid plan, grid street plan, or gridiron plan is a type of city plan in which streets run at right angles to each other, forming a grid. The infrastructure cost for regular grid patterns is generally higher than for patterns with discontinuous streets.
A pedestrian is a person travelling on foot, whether walking or running. In modern times, the term usually refers to someone walking on a road or pavement, but this was not the case historically.
Traffic calming uses physical design and other measures to improve safety for motorists, pedestrians and cyclists. It has become a tool to combat speeding and other unsafe behaviours of drivers in the neighbourhoods. It aims to encourage safer, more responsible driving and potentially reduce traffic flow. Urban planners and traffic engineers have many strategies for traffic calming, including narrowed roads and speed humps. Such measures are common in Australia and Europe, but less so in North America. Traffic calming is a calque of the German word Verkehrsberuhigung – the term's first published use in English was in 1985 by Carmen Hass-Klau.
A street is a public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable surface such as tarmac, concrete, cobblestone or brick. Portions may also be smoothed with asphalt, embedded with rails, or otherwise prepared to accommodate non-pedestrian traffic.
Bicycle-friendly policies and practices help some people feel more comfortable about traveling by bicycle with other traffic. The level of bicycle-friendliness of an environment can be influenced by many factors includingtown planning and cycling infrastructure decisions. A stigma towards people who ride bicycles and fear of cycling is a social construct that needs to be fully understood when promoting a bicycle friendly culture.
Level of service (LOS) is a qualitative measure used to relate the quality of motor vehicle traffic service. LOS is used to analyze roadways and intersections by categorizing traffic flow and assigning quality levels of traffic based on performance measure like vehicle speed, density, congestion, etc. In a more general sense, levels of service can apply to all services in asset management domain.
A dead end, also known as a cul-de-sac, no through road or no exit road, is a street with only one inlet or outlet.
Pedestrian zones are areas of a city or town reserved for pedestrian-only use and in which most or all automobile traffic is prohibited. Converting a street or an area to pedestrian-only use is called pedestrianisation. Pedestrianisation usually aims to provide better accessibility and mobility for pedestrians, to enhance the amount of shopping and other business activities in the area and/or to improve the attractiveness of the local environment in terms of aesthetics, air pollution, noise and crashes involving motor vehicle with pedestrians. However, pedestrianisation can sometimes lead to reductions in business activity, property devaluation, and displacement of economic activity to other areas. In some cases traffic in surrounding areas may increase, due to displacement, rather than substitution of car traffic. Nonetheless, pedestrianisation schemes are often associated with significant drops in local air and noise pollution, accidents, and frequently with increased retail turnover and increased property values locally. A car-free development generally implies a large scale pedestrianised area that relies on modes of transport other than the car, while pedestrian zones may vary in size from a single square to entire districts, but with highly variable degrees of dependence on cars for their broader transport links.
Edge city is a term that originated in the United States for a concentration of business, shopping, and entertainment outside a traditional downtown or central business district, in what had previously been a suburban residential or rural area. The term was popularized by the 1991 book Edge City: Life on the New Frontier by Joel Garreau, who established its current meaning while working as a reporter for The Washington Post. Garreau argues that the edge city has become the standard form of urban growth worldwide, representing a 20th-century urban form unlike that of the 19th-century central downtown. Other terms for these areas include suburban activity centers, megacenters, and suburban business districts. These districts have now developed in many countries.
Pedestrian malls, also known as pedestrian streets, are the most common form of pedestrian zone in large cities in the United States. They are typically streets lined with storefronts and closed off to most automobile traffic. Emergency vehicles may have access at all times and delivery vehicles may be restricted to either limited delivery hours or entrances on side streets.
An arterial road or arterial thoroughfare is a high-capacity urban road. The primary function of an arterial road is to deliver traffic from collector roads to freeways or expressways, and between urban centres at the highest level of service possible. As such, many arteries are limited-access roads, or feature restrictions on private access. Because of their relatively high accessibility, many major roads face large amounts of land use and urban development, making them significant urban places.
The street hierarchy is an urban planning technique for laying out road networks that exclude automobile through-traffic from developed areas. It is conceived as a hierarchy of roads that embeds the link importance of each road type in the network topology. Street hierarchy restricts or eliminates direct connections between certain types of links, for example residential streets and arterial roads, and allows connections between similar order streets or between street types that are separated by one level in the hierarchy By contrast, in many regular, traditional grid plans, as laid out, higher order roads are connected by through streets of both lower order levels An ordering of roads and their classification can include several levels and finer distinctions as, for example, major and minor arterials or collectors.
A car-free city or carfree city is a population center that relies primarily on public transport, walking, or cycling for transport within the urban area. Carfree cities greatly reduce petroleum dependency, air pollution, greenhouse gas emissions, automobile crashes, noise pollution, urban heat island effect and traffic congestion. Some cities have one or more districts where motorized vehicles are prohibited, referred to as car-free zones.
The fused grid is a street network pattern first proposed in 2002 and subsequently applied in Calgary, Alberta (2006) and Stratford, Ontario (2004). It represents a synthesis of two well known and extensively used network concepts: the "grid" and the "Radburn" pattern, derivatives of which are found in most city suburbs. Both concepts were self-conscious attempts to organize urban space for habitation. The grid was conceived and applied in the pre-automotive era of cities starting circa 2000 BC and prevailed until about 1900 AD. The Radburn pattern emerged in 1929 about thirty years following the invention of the internal combustion engine powered automobile and in anticipation of its eventual dominance as a means for mobility and transport. Both these patterns appear throughout North America. "Fused" refers to a systematic recombination of the essential characteristics of each of these two network patterns.
A cycle track, separated bike lane or protected bike lane, is an exclusive bikeway that has elements of a separated path and on-road bike lane. A cycle track is located within or next to the roadway, but is made distinct from both the sidewalk and general purpose roadway by vertical barriers or elevation differences.
Walkability is a measure of how friendly an area is to walking. Walkability has health, environmental, and economic benefits. Factors influencing walkability include the presence or absence and quality of footpaths, sidewalks or other pedestrian rights-of-way, traffic and road conditions, land use patterns, building accessibility, and safety, among others. Walkability is an important concept in sustainable urban design.
Permeability or connectivity describes the extent to which urban forms permit movement of people or vehicles in different directions. The terms are often used interchangeably, although differentiated definitions also exist. Permeability is generally considered a positive attribute of an urban design, as it permits ease of movement and avoids severing neighbourhoods. Urban forms which lack permeability, e.g. those severed by arterial roads, or with many long culs-de-sac, are considered to discourage movement on foot and encourage longer journeys by car. There is some empirical research evidence to support this view.
The concept of the neighborhood unit, crystallised from the prevailing social and intellectual attitudes of the early 1900s by Clarence Perry, is an early diagrammatic planning model for residential development in metropolitan areas. It was designed by Perry to act as a framework for urban planners attempting to design functional, self-contained and desirable neighbourhoods in the early 20th century in industrialising cities. It continues to be utilised, as a means of ordering and organising new residential communities in a way which satisfies contemporary "social, administrative and service requirements for satisfactory urban existence".
Automotive city or Auto City are cities that facilitate, and encourage, the movement of people via private transportation, through ‘physical planning’, e.g., built environment innovations and ‘soft programming’ e.g., social policy surrounding city street usage.
The Vancouver Greenway Network is a collection of greenways across Vancouver, British Columbia, Canada. Greenways are streets where pedestrians and cyclists are prioritized over motorized vehicles, through structures such as road closures and road diverters to prevent or limit motor vehicle traffic, widened sidewalk-promenades, narrowed road space, speed restrictions, bike lanes, raised sidewalks and speed bumps. The City of Vancouver hopes to create and maintain the trend of constructing new greenways to establish a network where, potentially, every citizen could access a city greenway within a 25-minute walking or a 10-minute cycling distance of their home.
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