Paper Two: Conceptual Models in Urban Design

Paper Two: Conceptual Models in Urban Design The present study aims to explore the concept of Emergence and Self-organisation as a new approach in the design process of urban systems. This strategy implies a Bottom-Up process in the formation of urban systems. However, urban development complies with various standards, guidelines and regulations concerning Building Control, Planning and Urban Policies, a Top-Down process by nature. How to reconcile the two processes is one of the objectives of this study. According to Schumacher, a Bottom-up urban growth process can still occur and emerge from the speculative nature of the market forces driving the real estate development (Schumacker, P., 2012). In his article ‘Urbanism beyond Planning’1, Schumacher retraces the rise and fall of modern urbanism through the economic and social dynamisms of the 20th century, and speculates on the possibilities of emergence of a ‘bottom up urbanism that produces urban order, coherence and urban identity without [master] planning’. It is argued that the contextual parameters and the normative attributes of the built environment which constitute the backbone of contemporary urban interventions are part of the extrinsic constraints that influence the ‘economics and functionality’ of urban systems, rendering the formation more adapted and best fitted to its environment in legislative or geographical sense. In this respect, urban modelling becomes an exercise of optimization through form-finding procedures. The aim in this chapter is not to present an extensive review of urban design models and theories, but to look at the main trends that contributed and are still influential in the shaping of the built environment. Urban Design Models Master-planning and urban design processes follow well-established procedures envisioned in the form of a series of drawings and diagrams, representing design considerations and development plan concept. Design considerations refer in general to all factors that influence the design. These include physical factors such as climate, ecology, drainage and flooding usually presented in a series of maps; planning and urban policy decisions on land uses, density and infrastructure, and the site potential and constraints acting upon the development. All this constitutes a dataset that contributes towards the formulation of the development plan concept. This task is traditionally tackled using conceptual diagrams of the future development, raising therefore the question of the role of diagrams in urban modelling. In this respect, ‘The Diagrams of Architecture’, a compilation of articles, retraces the history and instrumentality of diagrams in the design process and in the advancement of architectural discourse (Garcia, M. 2010). In the section ‘Urban Diagrams and Urban Modelling’, Shane, similarly to Lynch2, identifies three basic types of diagrams which relate to three different ideal models of cities, ‘Diagrams of Emplacement’ corresponding to ‘Cities of Faith’ or the ‘Cosmic’ model 1

www.patrikschumacher.com/Texts/Free Market Urbanism - Urbanism beyond Planning.html Kevin Lynch identified three normative models of city form: the ‘Cosmic’ model, the ‘Machine’ model and the ‘Organic’ model, each based on specific principles of spatial organisation (Lynch, K., ‘Good City Form’, 1984). 2

(Akkach, S., 2005); ‘Diagrams of Extension’ corresponding to ‘Location Theory’ types of cities or the ‘Rational’ model; and ‘Diagrams of Relations’ corresponding to ‘Cities of Networks and Relationships’ or the ‘Organic’ model (Shane, D.G., 2010, pp.80-87). The diagram becomes the ideal analogue, providing the principles for organizing the built environment by regulating the movements and activities of its inhabitants. In other words, diagrams become instrumental in space planning and facilitate the transcription of the physical environment in terms of both, its social and tectonic activities. The diagramming of highway and mechanical engineering requirements and the quantification of social activities contain value assumptions about structure and function, inevitably resulting in typologies. Diagrams become the media through which urban design and space planning gain social relevance. ‘Scientific management’ or ‘Taylorism’3 is a theory of management of the 1930s for analysing and synthesizing workflows in industrial plants in order to improve economic efficiency and labour productivity. The theory claims to include analysis, synthesis, logic, rationality, empiricism, work ethics, efficiency and elimination of waste, standardization of best practices4. The belief that cities can be formed according to scientific principles stems from the works of Baumeister, a German civil engineer and urban planner, who published a planning handbook in 1876, on ‘Town Extensions: their links with technical and economic concerns and with building regulations’5, in which traffic and mechanical engineering are regarded as the basis for the organisation of the city for a better control of hygiene and public health considerations. The modern city is then subdivided into zones for living, zones for working and zones for leisure for a better articulation and rational distribution of services. Standardized relationships such as the maximum space between buildings or the minimum space in dwellings are other aspects of the rational modern city. The city as a ‘machine’ designed by architects emphasized the spatial and formal organisation of the city and the social structures it would encompass. Le Corbusier for example, was convinced that the solution to most urban problems lies in the creation of the ‘right plan’, an appropriate and ‘universal’ model context-free and ideally with no interference from the stakeholders (Le Corbusier, 1935. pp 200-319). ‘La Ville Radieuse’ proposed as a blueprint of social reform, expressed his vision of the ideal city, which unlike the radial development of ‘La Ville Contemporaine’, was linear and based on the human body composition. Diagrams of the ideal form of a city like the ‘Garden City’ model of Howard or ‘Central Place Theory’6 model of Christaller are examples of conceptual models to deal with the number, size and location of agglomerations and their relationships into a larger urban system. The ideal pattern would be distorted by topographical inputs but the rationale remains quite simple. A regional city with its manufacturing infrastructure supplies a ring of satellite cities which in turn, stock the manufactured goods to be distributed locally; and to the wholesalers 3

Frederick Winslow Taylor, an American mechanical engineer, is regarded as the father of ‘Scientific’ management 4 Source: http://en.wikipedia.org/wiki/Taylorism 5 ‘Stadterweiterungen in technischer, baupolizeilicher und Wirtschaftlicher Beziehung’, Baumeister , R. 6 http://en.wikipedia.org/wiki/Central_place_theory

within its hexagonal satellite towns (Shane, D.G., 2005). In other words, the city is regarded as an economic engine in which space becomes a resource for production or consumption and the location of an agglomeration in a region of industrial production is dependent upon economic considerations regarding raw materials, labour and products distribution7.

Fig. 1.1: ‘Central Place’ Principles by Walter Christaller

Fig.1.2: ‘Garden City’ Principles

The ‘diagrams of relations’ and the corresponding city model are still influential in today’s urban interventions. The movement system and linkage in a city define the types of movements: vehicular [public/private] making the road network; and pedestrian/cyclists making a network of pathways and cycle-ways; and the relationship between the two types 7

http://en.wikipedia.org/wiki/Garden_city

and the facilities they serve. The road network in a city is a well-established hierarchy of roads regulating the flow and accessibility, highly standardized by the highway codes and conventions, defining types, connections and usage, and right-of-ways. Movement and Circulation diagrams are typically very popular and most urban space designs start with circulation diagrams as circulation is easily transcribed into the physical environment and thereby tends to correlate better with the urban form. Circulation refers to the designated spaces for movements across a city interconnecting the parts together into a network. In Graph Theory, movements are expressed in terms of their basic topological structure, a graph network made up of vertices or nodes and lines or edges connecting them and resulting in different patterns. Christopher Alexander, for example, defines two types of patterns, a semi-lattice and a tree. In a tree structure, urban components are connected but do not overlap, leading to highly segregated entities. On the other hand, unplanned urban environments follow a semi-lattice pattern (Alexander, C., 1964, p.87). For Alexander, the diagram is a visual device, capable of showing the structures as systematic expressions of the communities. Similarly, Haggett and Chorley define three basic types of circulation networks, the Branching network, the hierarchical tree structure, the Circuit network or closed loop, and the Boundary network or barrier network consisting of obstructing links to movement (Haggett, P., Chorley, R.J., 2008, pp.102-103). Nowadays, many techniques, such as ‘Travelling Salesman Circuit’ or ‘Shortest Path’ have been developed to optimize circulation networks, taking into account many parameters such as the construction cost, the users’ costs (travelling time and distance). Pedestrian and vehicular movements and their interface are therefore key factors in the shaping and design of the urban space. The street network provides opportunities for movement and accessibility. In fact, roads are classified in terms of whether they are only used for motion or for motion and accessibility, resulting in two main categories: the controlled-access highways (Motorways, Arterial roads) and the non-controlled–access roads (Collectors, local roads). This flow-based road network is hierarchical with local streets feeding into the collector roads, which in turn feed into the arterial roads which feed into the motorways. However, any road is ‘local’ in essence, in the sense that all roads are used and ‘built’ locally segment by segment, and any upgrading to a higher grade road depends mainly on economic and political factors. In this case, the ‘road’ or a ‘section of a road’ by becoming of ‘arterial’ or ‘motorway’ type, will be restricted only for the movements of vehicles and its connections within the global (regional or national) network clearly defined and mapped in the landscape. A well-known example illustrating the ‘Circulation Diagram’ or ‘Diagrams of relations’ model is the urban design movement of ‘New Urbanism’8, which promotes the segregation between pedestrian and vehicular movements resulting in ‘walkable neighbourhoods’ of 8

Source : http://en.wikipedia.org/wiki/newurbanism

mixed uses. The movement originated in the United States in the early 1980s, as an alternative to the ailing ‘modern city’ and gradually expanded to inform many aspects of real estate development, urban planning, and municipal land-use strategies. New Urbanism is strongly influenced by the pre-modern urban design standards prior to the rise of the extensive use of automobile and its implications in planning strategies. ‘New Pedestrianism’, a more recent idealistic adaptation of New Urbanism, is proposed by the urban designer and futurist American artist, Michael Arth in an attempt to solve various problems relating to social, health, energy, economic, aesthetic, and environmental factors, by reducing the role of the automobile (Arth, Michael E., 2010; pp. 120-139, 363-386). These strategies are claimed to promote the reduction of traffic congestion, the increase and supply of more affordable housing, and the control and rein of suburban sprawl (see fig. 1.3).

Fig. 1.3: Suburban design compared to New Urbanism and New Pedestrianism

New Urbanism contains value assumptions about the structure and function of the city. Its perspective considers the city as analogous to a living organism in the sense that natural laws and processes can be applied to the city seen as a socio-spatial system with communities, bound together by mutual interdependence and general consensus. In this sense, the ‘organic’ city model relies on a number of analogical assumptions derived from the nature of living organisms. The city is made up of distinct spatial and social units constituted of highly connected places and people forming the ‘neighbourhood’, seen as a residential unit with clearly defined boundary and of a specific size to support a primary school 9. The organic city is seen as a self-regulating and self-maintaining entity which, like an organism, can only grow to an optimum size. ‘Greenbelts’, while maintaining a direct contact with nature, have been introduced mostly as a measure of containing the growing city. The concept of ‘Neighbourhood’ is generally defined spatially as a specific geographic area; and functionally as a set of social networks. ‘A neighbourhood is the spatial unit in which face-to-face social interactions occur or the geographically localised community within a larger city, town, suburb or rural area’10. Neighbourhoods are seen as typically small social units larger than households, generated by social interactions among people living in close 9

Clarence Perry, an American planner and sociologist, introduced the concept of neighbourhood in 1929.

10

Source : http://en.wikipedia.org/wiki/Neighbourhood

proximity. The act of creating geographic areas identifiable with particular ‘social groups’, does not necessary entail the emergence of a ‘community’ life and raises issues relating to the social organisation of the city. Theories of urban sociology and the idea of emergence of communities go back to the concept of ‘social solidarity’ (‘Assabiyah’) introduced by Ibn Khaldun in the 14th century, to describe the fundamental bond of human society and group consciousness, and social cohesion in urban settings. Durkheim elaborated on the concept of ‘solidarities’ many centuries later, by defining two types, the ‘mechanical solidarity’ based on social bonds constructed on similarity and largely dependent on common beliefs and shared values, in the sense that people are united automatically when they share the same cultural values; and the ‘organic solidarity’ based on social differences and the division of labour, generating a variety of different but interdependent groups creating therefore social cohesion. Hillier uses a similar dichotomy to describe space-dependent social interactions and social bonds unrelated to space and maintains that spatial laws and the resulting spatial configurations through their effect on movements ‘are at once a constraining framework and a system of possibilities to be exploited by individuals’. He argues that spatial laws mediate the social construction of urban space through the patterns of movements they generate (Hillier, B., 2001). Many extensive recent studies question the form of cities by examining issues relating to the processes and the relationships between the constituent parts: ‘what is a good way of making a city’11? Many argue for the importance of continuity in time and space in the creation of urban space. In this respect, Rowe and Koetter particularly deal with this question and stress that design of urban space must be accomplished through ‘bricolage’ by the superimposition and remixing of pieces or fragments from the past, present and future and drawing them together through a process of collage directed by the context. Advocates of ‘Collage city’ model argue that many cities, due to the nature of their growth process, are already ‘collages’ of historic fragments. However, designing by ‘Collage’ amounts to accommodating and juxtaposing many different visions and the urban solution would typically include competing and opposing models such as the traditional city and the ‘radiant city’ of ‘towers in the park’ (Rowe, C.; Koetter, F., 1984). Camillo Sitte’s work12 also calls for this continuity in urban space design. Inspired by medieval and baroque designs, Sitte criticized the regularity and obsession with orthogonality and symmetry in urban space designs, comparing it with the irregularity of the unplanned and incrementally developed city, and emphasizing the creation of plazas and public squares enhanced by monuments and other aesthetic elements (Collins, G.R. & Collins, C. G., 2006). For him, the most important aspect of urban space is not the architectural shape or form of each building but the inherent quality of urban space, created by the use of artistic principles in building towns with the intent to achieving that spatial-temporal continuum observed in the medieval city (Ibid, p.15).

11

Lynch, K., ‘Good City Form’, 1984, pp. 38-40. Sitte, Camillo, an Austrian Architect and Planner published ‘City Planning According to Artistic Principles’ in 1889. 12

Recent developments of new towns in the region of Algiers have been designed following some of the principles of the ‘collage city’ model but also incorporating concepts from the normative ‘organic’ model. The towns of Sidi Abdellah and Bouinan, or Boughezoul, have been programmed as a measure to curb urban sprawl and as part of The National Town Planning Programme (Schéma National d’Aménagement du Territoire), to tackle the increasing concentration of the national population and economic activities along the coast: two-thirds of Algeria’s population live on 5% of the nation’s land.

Fig. 1.4: Sidi Abdellah13, New Town near Algiers

The radial organization of the new town of Sidi Abdellah is planned to provide 30 000 house units and a large range of public facilities and services designed to provide for a population of over half million inhabitants on a designated area of over 30 square kilometres. Amongst these facilities, it will house an IT compound (86ha) a la ‘Silicon Valley’, a university hospital (10ha) and a large sports centre with a stadium of 20 000 seats.

Fig. 1.5: Boughezoul, a New Town South West of Algiers

Similarly, Boughezoul is inscribed in the national programme that establishes different types of cities situated in the southern parts of Algeria as a measure to balance the concentration of large towns of the Mediterranean coast. Boughezoul, 160km south west of Algiers and with a 13

http://wikimapia.org/17144947/fr/Nouvelle-Ville-Sidi-Abdellah

projected population of 350,000 inhabitants by 2025, is aimed not only at accommodating the overflow of the capital suburbs but also to changing the national population distribution. The master plan of this new town follows a regular network of roads defining a regular subdivision of the terrain into different functional zones. The new town of Hassi Messaoud located in the Sahara desert at about 80km east of Ouargla, is also programmed for the same purpose. With a projected population of 80 000 inhabitants, the town will in the first phase cover an area of about 20 square km with a separate industrial park and a ‘green peripheral belt’ for protection against sandstorms14. The wide deployment of the town and the large road reservation, contradicts the most basic principle observed in Saharan traditional developments, that is the reduction of surfaces exposed to the sun to reduce heat gain. Moreover, the scarce water resources typical of the desert climatic conditions and the lack of water management system, renders the ‘Garden City’ organisation unavailing. The design follows a rigid zoning and hierarchical model of a street system which defines hierarchically organised residential areas. The industrial zone is three kilometres east of the town.

The town will be constituted of four districts and a town centre; each district will be composed of two neighbourhoods, each of which will be made up of two or three basic residential units. These projects and many others are presented as the “new Algerian model of urbanism and architecture” with strong environmental claims promoting renewable energies, clearly reminiscent of Abu Dhabi development in stressing the importance of the urban architecture expressed in a geometrical grid with large avenues, landscape landmarks and iconic buildings. The often acclaimed sustainability is only invested in the introduction of new technologies not 14

Source : http://portail.cder.dz/spip.php?article3438

in the design principles that inherently structure the urban space in environmental, cultural and economic terms. These new towns have been designed following a universal hierarchical model based on an urban design protocol which establishes principles believed to create ‘good’ urban places. The generic model maintains hierarchical relationships between the elements of urban design, operating from the macro scale of the urban structure such as zoning, transport and infrastructure networks, to the micro scale such as landscaping, street furniture and lighting. The layouts of the above examples of new towns under construction, demonstrate that the urban theories of a ‘good city form’ outlined above, are still relevant and instrumental in the design process of the contemporary city. Whether these are situated in America, Asia or Africa, they still follow the same generic model which is generally based on a hierarchical system of road and public utilities networks and their transcription in space to create sociospatial hierarchically connected units. Generally, the main argument advanced for the ‘highway and mechanical’ engineering model is the economy, in the sense that a regular grid system of roads and public utilities networks is more cost-effective. However, in Graph Theory, it has been established that a regular grid does not necessarily create the shortest or the most economic links between nodes. Moreover, a network of large roads and avenues, some of them dual carriageways, is not always the most economical solution, such as the case of the Saharan new town as it increases surface exposure to the sun and create the problem of heat gain, which is then resolved, if any, by other protective means. On the other hand, straight streets by their nature encourage higher speed; while narrower winding streets reduce speed, creating a speed control mechanism in the very structure of the street network. The above examples clearly demonstrate a desire to accomplish a design that can instigate and encourage ‘qualitative’ urban life. Since the publication of ‘The Death and Life of Great American Cities’ in 1961, there seems to be a general consensus that unplanned urban systems have a certain ‘quality’ to them that was lost in the planned counterparts and that most architects crave to re-create. In this respect, Jacobs argued that ’modernist urban planning rejects the city, because it rejects human beings living in a community characterized by layered complexity and seeming chaos’ (Jacobs, J., 1961). The planned cities seem to be stripped of their power in creating opportunities for the development of diverse communities. They generally follow pre-defined comprehensive plans established by the local authorities and stakeholders to determine areas suitable for urban development. The prevailing normative models in urban interventions, despite their differences and their comprehensive applications, have failed to take into account the dynamic dimension of urban systems and as such remain inadequate representations. In other words, the design process implicated in the planned cities and urban developments is inherently static, generating rigid structures that cannot cope with the ever-changing conditions and imperatives. The present study proposes a generative model based on the dynamics and processes that drive the urban form of unplanned settlements. The following chapter presents the different techniques employed in urban modelling and particularly the generative techniques. In urban modelling, a generative method implies the

application of a set of rules to accomplish some operations. When a generative model is used as part of the design process, can this process be considered as ‘generative design process? A generative design process is in general seen as a method based on an algorithm to explore design possibilities. A generative design process typically requires a ‘design schema; a dynamic environment for creating variations and assessment techniques for selecting desirable outcomes’15. The following sections aim to demonstrate the extent to which the proposed generative model forms part of the design process and whether this method can be considered as a generative design process with the architect controlling the process through the code definition and supervising the production of architectural forms. It has been suggested that urban systems can be generated through the process of self-organisation and emergence based on a predefined set of ordering principles that control the interactions between the individual parts. It has also been shown that the circulation system and its direct manifestation in the built environment is the driving force in planning practices, as it channels not only movements of vehicles and people but also services (Water supply system, Electricity and Telecommunications, Drainage & Sewage). Paradoxically, these considerations raise an important question as to whether a ‘bottom-up’ process is capable of generating entities that can accommodate these services according to the prescribed standards and regulations. The answer lies in the nature of the form-generating rules and restrictions of the model which makes the main concern of the next chapter.

Summary and Conclusions This section outlined the mainstream principles in urban design practices. It reviewed the principal concepts and diagrams used in representing and designing urban systems. In conclusion, circulation patterns directed urban diagrams and strongly influenced the overall structure of urban forms.

15

Source: www.wikipedia.org. Many contributions have been made to define ‘Generative Design Process’, one of these is by Soddu, Celestino, 1992.