**2. Urban blocks**

The city block is the fundamental element of physical structure of urban areas [4]. The block is primarily a plot of land defined all around by a multitude of planned and unplanned road and streets [5] and defined by an edge and an interior where the edge is directly connected with the street and is understood as the public realm and the interior is a private zone.

Regarding urban form, Moudon indicates four levels of resolution are commonly recognized, corresponding to the "building/lot," the "street/block," the "city," and the "region" [3].

In a parallel way, it was Conzen who recognized the tripartite division of the townscape, the town plan, or ground plan, comprising street, plots, and block plans of buildings [6].

#### **3. The role of blocks in the urban spaces**

The urban block must be identified as the most important typological element in the composition of urban spaces [7] because as part of the urban continuum, an urban block is that singular element that is spatially and functionally optimized to support different circumstances of everyday life [7]. Where the urban block is the tool for urban design, the pattern of streets and squares become the result of positioning of the blocks [7]. Also, the size and shape of urban blocks contribute effectively to the formation of the character of the environment [2]. The formation and scope of urban blocks are also effective in determining traffic patterns and visual growth parameters [2].

Additionally, the block faces respond to buildings (the internal load of blocks) and street structure (the external load of blocks). In fact block faces participate in defining the edges and character of the street network; they act as the interface between architectural form and urban form [8].

In fact, the city block facilitates close integration into the surrounding urban structure. It is linked to the network of city streets and building lines, which define it spatially and geometrically. The city block is a continuous closed urban space, accessible from all sides, that ensures the continuity of surrounding structures and exterior urban areas [9].

Therefore, the city block is a spatial system that is extremely complex and flexible and lends itself particularly well to integrating diverse, differentiated modes of behavior, activities, and forms of appropriation [9, p. 22].

#### **4. Thoughts on urban blocks**

Urban blocks can be traced in a variety of thoughts, and the concepts and factors derived from ideas of this research about the block can be divided into three

#### *Toward Practical Criteria for Analyzing and Designing Urban Blocks DOI: http://dx.doi.org/10.5772/intechopen.90504*

categories: size, dimensions (2D, 3D), and shape; position; and function and meaning. It should be said that each of these categories can have effects on each other, mutually. In the following, spatial qualities which are created by these factors are also discussed. All the factors relate to the urban blocks could be considered in the three categories:


applications with disrupted forms, without interconnected urban masses and blocks

The city block is the fundamental element of physical structure of urban areas

Regarding urban form, Moudon indicates four levels of resolution are commonly recognized, corresponding to the "building/lot," the "street/block," the "city," and

The urban block must be identified as the most important typological element in the composition of urban spaces [7] because as part of the urban continuum, an urban block is that singular element that is spatially and functionally optimized to support different circumstances of everyday life [7]. Where the urban block is the tool for urban design, the pattern of streets and squares become the result of positioning of the blocks [7]. Also, the size and shape of urban blocks contribute effectively to the formation of the character of the environment [2]. The formation and scope of urban blocks are also

Additionally, the block faces respond to buildings (the internal load of blocks) and street structure (the external load of blocks). In fact block faces participate in defining the edges and character of the street network; they act as the interface

In fact, the city block facilitates close integration into the surrounding urban structure. It is linked to the network of city streets and building lines, which define it spatially and geometrically. The city block is a continuous closed urban space, accessible from all sides, that ensures the continuity of surrounding structures and

Therefore, the city block is a spatial system that is extremely complex and flexible and lends itself particularly well to integrating diverse, differentiated modes

Urban blocks can be traced in a variety of thoughts, and the concepts and factors

derived from ideas of this research about the block can be divided into three

effective in determining traffic patterns and visual growth parameters [2].

In a parallel way, it was Conzen who recognized the tripartite division of the townscape, the town plan, or ground plan, comprising street, plots, and block plans

[4]. The block is primarily a plot of land defined all around by a multitude of planned and unplanned road and streets [5] and defined by an edge and an interior where the edge is directly connected with the street and is understood as the public

It can be said that urban blocks have the potential to define and create the balance between lots and streets, so that buildings and streets are considered simultaneously and in parallel with each other. Therefore, attempts were made to define factors required for analyzing this element by examining the views and theories related to blocks. To this end, first, the concepts were extracted and then were clustered by examining their interrelationships. Finally, a categorized list of effective factors in design of urban blocks was developed that can be used as a guideline

that could be representative of space [2].

*Sustainability in Urban Planning and Design*

for the design of this essential element.

realm and the interior is a private zone.

**3. The role of blocks in the urban spaces**

between architectural form and urban form [8].

of behavior, activities, and forms of appropriation [9, p. 22].

exterior urban areas [9].

**186**

**4. Thoughts on urban blocks**

**2. Urban blocks**

the "region" [3].

of buildings [6].

• function and meaning.

#### **4.1 Size, dimensions, and shape**

#### *4.1.1 Two-dimensional space*

Many studies have focused on the formal aspects of blocks, especially the size and dimensions of urban blocks, often to achieve optimal sizes for them. Krier [7] who compared and studied different sizes of urban blocks suggested that the sizes of blocks should contribute to integration in the context [2]. Vialard [8] states that such ideas seek to restore a human-scale environment where in buildings and blocks interact closely. In general, in this view, large urban blocks tend to get smaller to achieve the optimum size. One of the effective factors in this regard is the determination of the level of privacy and frontage of buildings, which supports concentrated urban centers [4]. This also induces a sense of transition and transfer between public, semipublic, and private spaces [10].

Conzen [11], Bentley [12], and Jacobs [13] advocate small-sized blocks, because they believe that these blocks enhance physical and visual permeability and enhance public awareness of use options. Siksna [4] supports the sustainability and durability of small urban blocks and in research on the desired size of blocks and the design of blocks in four American cities and also considers the durability and sustainability of "small-block cities" as high.

Talen [10] refers to factors such as the internal connection of blocks and their connectivity, which relates to the relationship between the blocks and the street network. It can be said that very large urban blocks affect connectivity [14]. As Scheer and Petkov [15] state that although these large urban blocks, especially those that include large shopping malls, strengthen the external connection of the blocks with their surrounding environment, they are isolated locally from the environment and have weak internal connections. Maitland [16] considers these major shopping centers as the main factor effective in the separation of blocks and streets. In his opinion, those blocks that contain large shopping centers create privacy in the inner space of the block, rather than at the edges, and though they create footpaths, they limit the connection of these paths to the internal space and weaken or interrupt the pedestrian access to the surrounding area. A similar point can be seen in introverted blocks with cul-de-sacs as a type of POD development, because the cul-de-sacs create autonomous and car-dependent spaces that grow apart from other units in the context and are detached socially and physically from the outside world [2]. Song and Knapp [14] also consider the street intersections, the length of cul-desacs, the block perimeter, and the residential density of blocks as effective on connectivity between neighborhoods.

It is noteworthy that in the close relationship between the street and the block, these patterns require sustainability to evolve so that initial patterns can survive under conditions of change, so one of the factors affecting sustainability is the block size. According to Siksna [4] blocks of different sizes can achieve sustainability in block patterns and access networks, but large blocks, although can be largely stable, significantly change the composition of blocks and streets, as if they tend to be disintegrated. Thus, taking into account the corresponding relationship between factors such as the block size, the level and pattern of the access network, and the relationship between them is effective in achieving the desired size. Owens and Southworth [17] state that the street patterns (gridiron, fragmented parallel, wrapped parallel, loops, and cul-de-sac) are effective in creating a variety of urban networks (open and interconnected to closed and discontinuous ones) and believe that changing open and interconnected street patterns into closed and discontinuous ones will separate neighborhoods from their surroundings and thus reduce pedestrian access. According to their study on urban-edge communities, street patterns are related to block sizes (the number of blocks), the degree of connectivity (the number of intersections), and accessibility (the number of access points).

Martin and March [18] studied the typology of different physical layouts and systematically compared land occupation by building density and its consequences for land occupation, adequate access, create open spaces, and the possibility to enjoy daylight. Therefore, configuration is important, because you can create different configurations with the same density on the land. On the other hand, segre-

Berghauser Pont and Haupt [19] developed a matrix called "Spacemate," in which a variety of building layouts fit into a block based on various types of

densities. This matrix correlates the area of the block, the area of the open space, the ground floor area, and total floor area with different types of development. In general, as Krier [5] suggests, there must be equilibrium between the open space

Some scholars believe that the layout of the blocks are defined based on internal arrangement of block components, such as Moudon [20] who defines the layout of the blocks according to the location of the buildings and alleys, based on the observations of progressive evolution of block patterns, land plots, and construction patterns in a residential neighborhood around Alamo Square in San Francisco. Also, according to Conzen, plots in blocks can be taken into three forms: [2] back to back, one front to the main street and the front to the alley and two fronts with a common border on the main street. In fact, the location of plots in blocks and the location of blocks relative to each other represent the relative location of each of these elements relative to other elements and how this affects the spatial configuration and layout

In the same way, Boffet and Serra [21] investigated the three principles of proximity, similarity, and good continuation of Gestalt theory and used indicators such as the distance between the gravity centers of buildings, and the geometric indices of buildings including orientation, surface, and elongation, to identify spatial structures within urban blocks. Their study can be used to follow Gestalt theory in the study of the spatial structure between blocks or in a super block. On this scale, Gestalt principles such as proximity, similarity, good continuation, symmetry, and enclosure can be used to understand the alignment of blocks in a superblock as a whole, the location of buildings in block, and spatial configuration of urban blocks and also to evaluate indicators such as distance between gravity centers of blocks, geometric shape

On the other hand, the other scholars examined the block size based on the location and position of blocks. Talen [10] in her book, *City Rules*, and Krier [5] in studies on European cities with organic growth state that often central blocks close to the urban core are smaller, more fine-grained, and more complex, but as we move toward areas with lower population densities and with rural behavior, urban blocks gradually become simpler, larger, and longer, changing ultimately to single

Rossi [22] suggests factors such as continuity of the city reinforced by continuity in time, the underlying structure of the city as a basis for development and adaptation to new uses, and consideration of the city as a repository of collective memory that can be achieved through physical continuity of urban form (via layering of buildings

and their deployment in larger and existing urban structures) [8].

gation of urban blocks also affects their layout.

*DOI: http://dx.doi.org/10.5772/intechopen.90504*

*Toward Practical Criteria for Analyzing and Designing Urban Blocks*

influenced by orientation, surface, and elongation.

units with isolated forms in context [2].

**4.3 Function and meaning**

**189**

and the building density.

**4.2 Position**

of blocks.

In terms of shape, blocks can take a wide variety of geometric shapes such as triangular, rectangular, square, polygon, ellipse, semicircular, or even circular. However, their main geometric shapes are based on different architectural and urban design frames, design and quality of interior space, and lighting conditions in apartments [9]. Also, "the corners of city blocks can be designed with gaps so that the corner buildings receive adequate light. They can also be completely removed or 'beveled'. Another possibility is creating especially wide or narrow corner buildings" [9, p. 21]. Generally, the geometric shapes of blocks and their corner forms are factors that shape urban block configuration (**Figure 1**).

#### *4.1.2 Three-dimensional space*

Talen [10] suggests a minimum distance between the inner space of the block and the street for creating enclosure. In general, enclosure depends on two factors, i.e., the distance between the blocks and the ratio of the block height to the width of the passage. Changes in these proportions and distances resulting from changes in street width, the amount of block setbacks from the edge of the street, and the height of the blocks affect the enclosure of spaces and, in turn, their human scale.

**Figure 1.** *Samples of block's corner design [9].*

*Toward Practical Criteria for Analyzing and Designing Urban Blocks DOI: http://dx.doi.org/10.5772/intechopen.90504*

Martin and March [18] studied the typology of different physical layouts and systematically compared land occupation by building density and its consequences for land occupation, adequate access, create open spaces, and the possibility to enjoy daylight. Therefore, configuration is important, because you can create different configurations with the same density on the land. On the other hand, segregation of urban blocks also affects their layout.

Berghauser Pont and Haupt [19] developed a matrix called "Spacemate," in which a variety of building layouts fit into a block based on various types of densities. This matrix correlates the area of the block, the area of the open space, the ground floor area, and total floor area with different types of development. In general, as Krier [5] suggests, there must be equilibrium between the open space and the building density.

#### **4.2 Position**

size. According to Siksna [4] blocks of different sizes can achieve sustainability in block patterns and access networks, but large blocks, although can be largely stable, significantly change the composition of blocks and streets, as if they tend to be disintegrated. Thus, taking into account the corresponding relationship between factors such as the block size, the level and pattern of the access network, and the relationship between them is effective in achieving the desired size. Owens and Southworth [17] state that the street patterns (gridiron, fragmented parallel, wrapped parallel, loops, and cul-de-sac) are effective in creating a variety of urban networks (open and interconnected to closed and discontinuous ones) and believe that changing open and interconnected street patterns into closed and discontinuous ones will separate neighborhoods from their surroundings and thus reduce pedestrian access. According to their study on urban-edge communities, street patterns are related to block sizes (the number of blocks), the degree of connectivity (the number of intersections), and accessibility (the number of access points). In terms of shape, blocks can take a wide variety of geometric shapes such as triangular, rectangular, square, polygon, ellipse, semicircular, or even circular. However, their main geometric shapes are based on different architectural and urban design frames, design and quality of interior space, and lighting conditions in apartments [9]. Also, "the corners of city blocks can be designed with gaps so that the corner buildings receive adequate light. They can also be completely removed or 'beveled'. Another possibility is creating especially wide or narrow corner buildings" [9, p. 21]. Generally, the geometric shapes of blocks and their corner forms

are factors that shape urban block configuration (**Figure 1**).

Talen [10] suggests a minimum distance between the inner space of the block and the street for creating enclosure. In general, enclosure depends on two factors, i.e., the distance between the blocks and the ratio of the block height to the width of the passage. Changes in these proportions and distances resulting from changes in street width, the amount of block setbacks from the edge of the street, and the height of the blocks affect the enclosure of spaces and, in turn, their human scale.

*4.1.2 Three-dimensional space*

*Sustainability in Urban Planning and Design*

**Figure 1.**

**188**

*Samples of block's corner design [9].*

Some scholars believe that the layout of the blocks are defined based on internal arrangement of block components, such as Moudon [20] who defines the layout of the blocks according to the location of the buildings and alleys, based on the observations of progressive evolution of block patterns, land plots, and construction patterns in a residential neighborhood around Alamo Square in San Francisco. Also, according to Conzen, plots in blocks can be taken into three forms: [2] back to back, one front to the main street and the front to the alley and two fronts with a common border on the main street. In fact, the location of plots in blocks and the location of blocks relative to each other represent the relative location of each of these elements relative to other elements and how this affects the spatial configuration and layout of blocks.

In the same way, Boffet and Serra [21] investigated the three principles of proximity, similarity, and good continuation of Gestalt theory and used indicators such as the distance between the gravity centers of buildings, and the geometric indices of buildings including orientation, surface, and elongation, to identify spatial structures within urban blocks. Their study can be used to follow Gestalt theory in the study of the spatial structure between blocks or in a super block. On this scale, Gestalt principles such as proximity, similarity, good continuation, symmetry, and enclosure can be used to understand the alignment of blocks in a superblock as a whole, the location of buildings in block, and spatial configuration of urban blocks and also to evaluate indicators such as distance between gravity centers of blocks, geometric shape influenced by orientation, surface, and elongation.

On the other hand, the other scholars examined the block size based on the location and position of blocks. Talen [10] in her book, *City Rules*, and Krier [5] in studies on European cities with organic growth state that often central blocks close to the urban core are smaller, more fine-grained, and more complex, but as we move toward areas with lower population densities and with rural behavior, urban blocks gradually become simpler, larger, and longer, changing ultimately to single units with isolated forms in context [2].

#### **4.3 Function and meaning**

Rossi [22] suggests factors such as continuity of the city reinforced by continuity in time, the underlying structure of the city as a basis for development and adaptation to new uses, and consideration of the city as a repository of collective memory that can be achieved through physical continuity of urban form (via layering of buildings and their deployment in larger and existing urban structures) [8].

regard, a perimeter block type of construction is proposed for blocks that place the private open spaces at the back of the buildings and the public ones in front,

Hoyt (1933) also refers to a variety of form-based division patterns for urban

Oikonomou [23], in a research, focuses on the design process of urban blocks to create a community block based on environmental sustainability goals (mobility and accessibility, land use, natural environment, resource management, and economic aspects). Investigating layers of an urban block (street, plot, buildings, and open space) is done taking into account factors such as function; ownership; mixed land use; diversity of buildings; types of open spaces and public facilities; spatial domains and observance of hierarchies in private, semiprivate/semipublic, and public spaces; income and

Examining and summarizing different perspectives on each of these variables resulted in determining the effects of each block-based variable on spatial qualities

2D Size of blocks Spatial integration, human scale,

Street pattern Connectivity, permeability

3D Density Spatial configuration, layout, spatial

Land use Adaptability, durability, variety Access Spatial layout, configuration,

Meaning Memorability, sustainability, durability

Enclosure Human scale, spatial layout

The amount of privacy and frontage Spatial hierarchies, continuity, spatial

integration

balance

enclosure, physical and visual permeability, durability

Climate, spatial configuration

Spatial configuration and layout

Spatial continuity and integration

connectivity, permeability

social mixing orientation of buildings based on sunlight; and so on (**Figure 3**).

**Categories Variable Impact**

their corners

Position Arrangement of buildings in the

*The spatial qualities affected by the block-based variables.*

and alleys

continuation

Geometric shape of the blocks and

block, the location of the buildings,

Proximity, similarity, and good

Function and meaning Block subdivision patterns Configuration

*[17]; Bürklin and Peterek [9]; Rossi [22]; Moudon [20]; Berghauser Pont and Haupt [19, 25].*

**5. Sorting practical concepts: from macro-concepts to indicators**

In this section, the findings of the previous section are used to develop a practical checklist of the most important aspects required for the assessment of urban

*Sources: Adapted from Krier [5, 7]; Talen [10]; Siksna [4]; Conzen [11]; Jacobs [13]; Maitland [16]; Owens and Southworth*

distinguishing the internal and external spaces [12].

*DOI: http://dx.doi.org/10.5772/intechopen.90504*

*Toward Practical Criteria for Analyzing and Designing Urban Blocks*

blocks based on their type of use [10] (**Figure 2**).

(**Table 1**).

shape

Dimension and size of blocks and

**5.1 Procedure**

**Table 1.**

**191**

#### **Figure 2.**

*Some possible block arrangements for 40 acre tracts. According to Hoyt's analysis (1933, 431), "A" made sense (i.e., would yield the most aggregate value) where "each square foot is of equal importance." "C" the most common arrangement made sense for residential or apartment use; "1" made sense for commercial use since it has the most street frontage, but it is unrealistic because no subdivision would be composed entirely of commercial lots (Hoyt did not comment on the value of arrangements "B" and "E") [10].*

Regarding visual permeability, Bentley [12] stresses the need for front and rear sides for blocks. The front side faces public spaces for more public functions, and the rear side includes activities that have the highest degree of privacy. In this

### *Toward Practical Criteria for Analyzing and Designing Urban Blocks DOI: http://dx.doi.org/10.5772/intechopen.90504*

regard, a perimeter block type of construction is proposed for blocks that place the private open spaces at the back of the buildings and the public ones in front, distinguishing the internal and external spaces [12].

Hoyt (1933) also refers to a variety of form-based division patterns for urban blocks based on their type of use [10] (**Figure 2**).

Oikonomou [23], in a research, focuses on the design process of urban blocks to create a community block based on environmental sustainability goals (mobility and accessibility, land use, natural environment, resource management, and economic aspects). Investigating layers of an urban block (street, plot, buildings, and open space) is done taking into account factors such as function; ownership; mixed land use; diversity of buildings; types of open spaces and public facilities; spatial domains and observance of hierarchies in private, semiprivate/semipublic, and public spaces; income and social mixing orientation of buildings based on sunlight; and so on (**Figure 3**).

Examining and summarizing different perspectives on each of these variables resulted in determining the effects of each block-based variable on spatial qualities (**Table 1**).


*Sources: Adapted from Krier [5, 7]; Talen [10]; Siksna [4]; Conzen [11]; Jacobs [13]; Maitland [16]; Owens and Southworth [17]; Bürklin and Peterek [9]; Rossi [22]; Moudon [20]; Berghauser Pont and Haupt [19, 25].*

#### **Table 1.**

*The spatial qualities affected by the block-based variables.*
