PUBLIC PLACES- URBAN SPACES The Dimensions of Urban Design Matthew Carmona, Tim Heath, Taner Oc and Steven Tiesdell Architectural Press
Chapter-9
THE TEMPORAL DIMENSION Summary Arnav Saikia (2013MUD007)
INTRODUCTION: Temporal dimension of urban design discusses 'time' dimension, the fourth dimension. As time passes, spaces become lived-in, places made more meaningful by their time-thickened qualities. Lynch argued that we experience the passage of time in the urban environment in two ways 'rhythmic repetition' and 'progressive and irreversible change'. Three aspects of urban design’s temporal dimension
As activities are dynamic in space and time, environments are used differently at different times. Although environments relentlessly change over time, a high value is often placed on some degree of continuity and stability. Environments will change over time, while, equally, urban design projects, policies, etc., will be implemented over time.
TIME CYCLES: The first way in which we know that time has passed is through rhythmic repetition. The main time cycles are based on natural cycles, with the dominant cycle being the continuous cycle of day and night, involving sleeping and waking and various bodily cycles. Other cycles – those of working and leisure time, the cycle of meals, etc., – are overlain on this basic cycle.
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|Temporal Dimension Summary The Time Management of Public Space: The timing of activities may need to be managed. One of Jacobs’ four conditions for generating ‘exuberant diversity’ was to ensure the presence of people who go outdoors on different schedules (Jacobs, 1961: 162). Lynch (1981: 452), for example, recognised that activities may be prohibited at certain times to prevent conflicts; separated in time to alleviate congestion; or brought together in time to allow connections and a sufficient density of use (e.g. the establishment of market days). THE MARCH OF TIME: A second way in which we know that time has passed is through evidence of progressive and irreversible change. Urban environments are continuously and inexorably changing. Any intervention into the physical fabric of a place irreversibly changes its history for all time, becoming part of that history. The pioneer Modernists visualised sweeping away the cramped and unhealthy cities of their time, replacing them with a new and radically different environment consisting of high-rise buildings standing among trees and vegetation. Conservation: Accepting that the reasons for conserving historic building and environments are many, and often culture-, context- and building-specific, Tiesdell et al (1995: 11–7) list the more common justifications:
Aesthetic value – have historic buildings and environments are valued because they are intrinsically beautiful or because they have a scarcity value. Value for architectural diversity and contrast – existing environments are valued for the architectural diversity that results from the proximity of buildings of many different ages. Value for environmental diversity and contrast – within many cities, there is often a stimulating contrast between the human-scale environment of their historic areas and the monumental scale of their Central Business Districts. Value for functional diversity – a diverse range of different types of space in buildings of varying ages, enabling a mix of uses. Older buildings and areas may offer lower rents allowing economically marginal but socially important activities to have a place in the city.
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|Temporal Dimension Summary
Resource value – as buildings are committed expenditure, their re-use constitutes conservation of scarce resources, a reduction in the consumption of energy and materials in construction and good resource management. Value for continuity of cultural memory and heritage – visible evidence of the past can contribute educationally to the cultural identity and memory of a particular people or place, giving meaning to the present by interpreting the past. Economic and commercial value – older environments provide a distinctive sense-of-place, offering opportunities for economic development and tourism Preservation
Conservation
Revitalisation
Stewardship
Protection (preservation) of buildings & structures
Management of change
Economic development to enable to be protected through being in active use
Area management to protect and enhance sense- and quality-of-place.
Challenge
Protection of elite buildings.
Protection of many buildings – but too many to all be museums or to be protected at public expense
Economic development that is sensitive to sense-of-place and to historic buildings
Manage conflicts between different land uses. Social character. Physical changes
Key Actors
Art historians
Conservation planners
Conservation planners. Experts in economic development
Conservation planners. Urban managers and place management organisations
Rationales
Continuity of Place - A Continuing Narrative: In a world of rapid change, visual and tangible evidence of the past is valued for the sense-of-place and continuity it conveys. As the elements of the city change at different rates, some ‘essence’ of a city’s identity is retained despite ongoing and constant change. The relative permanence of an urban space helps establish its qualities as a meaningful place, while its physicality provides tangible record of the passage of time and embodies ‘social memory’. Obsolescence: Obsolescence is the reduction in the useful life of a capital good. Obsolescence is primary an outcome of the inability of ‘fixed’ urban structures and locations to adapt to change, whether technological, economic, social or cultural.
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|Temporal Dimension Summary When buildings are regarded as obsolescent, a distinction should also be made between obsolescence in their current use and that for any use. Obsolescence can be cured by the change of use. A distinction should also be made between ‘curable’ obsolescence (that which is cost-efficient to cure) and non-curable obsolescence (that which is not cost-efficient to cure). Time Frames of Change: An essential element of urban design’s time dimension is the need for urban designers to understand what stays the same and what changes over time. While street and plot patterns survive a long time, buildings and, in particular, land uses are less resilient. Conserving building from the past may have been through simple economic necessity, it was also an expression of certain aesthetic and cultural values – the urban scene was considered sufficiently desirable, culturally or economically or both, to be retained rather than demolished. Resilience and Robustness: Resilience is the ability to resist change without undue deformation (i.e. it resists the wearing effects of time and change – that is, physical and structural obsolescence). Robustness is the ability to accommodate change without significant change in the physical form (i.e. it resists functional obsolescence). i) Cross-sectional depth
ii) Access
iii) Room shape & size
Cross-sectional depth has a critical impact on the need for artificial lighting and ventilation, which in turn affects the variety of uses that can be accommodated. As most building uses require natural light and ventilation, buildings that are too deep cannot easily change use. Llewelyn-Davies (2000: 94) outlines the implications of different cross-sectional building depths: Depths less than 9 m provide potential for good daylighting and ventilation but are usually too shallow for a central corridor and have limited flexibility in internal planning. Depths between 9 and 13 m provide naturally lit and ventilated space and the opportunity for a central corridor (and, therefore, optimum robustness). Depths between 14 and 15 m still facilitate sub-division, but some artificial ventilation and more artificial lighting are usually required. Depths of greater than about 16 m require increasing amounts of mechanical ventilation and artificial lighting, and accordingly are more energy-intensive As all buildings need some links to the outside world, the number of access points – and, as critically, egress points in the event of fire – governs how readily a building can adapt to a variety of uses. Building height is a particular constraint in this respect – in a tall building, the upper floors have restricted links to the outside, and, thus, are less suitable for a wide range of uses In buildings intended to be robust, the rooms need to be sized to accommodate a broad range of activities, while also being capable of subdivision (which may relate to window positions) and/or being joined together to create larger spaces. In domestic buildings, rooms that are 10–13 m2 in area, for example, can serve as bedrooms, kitchens, living rooms or dining rooms. Dwellings consisting of a series of rooms of this size have proved relatively robust during cycles of change between family houses and smaller flats (see Moudon 1987). Brand (1994: 192) also contends the rectangle is the only configuration of space that grows well, sub-divides well and is efficient to use
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|Temporal Dimension Summary Social Change and Gentrification: The discussion is about how processes of change over time impact on the building stock and physical fabric of cities. Many of these changes stem from profound social and economic shifts. Sometime these changes might be positive while sometimes the processes might be negative. Gentrification is a politically loaded term. The political right generally prefers less ideologically charged words such as regeneration, revitalisation and renaissance, which are seen as ‘natural’ processes of city development in which some displacement is inevitable and might even be desirable. Gentrification has been identified as a potential by-product of urban design that can lead to social fragmentation. The solution to gentrification is to build more new-traditional neighbourhoods, so that older neighbourhoods do not become over-valued thwough scarcity. MANAGING CHANGE OVER TIME: Urban design operates across numerous time frames – almost all of which necessitate a long-term perspective. While designers may have a relatively shortterm involvement in particular development projects, created environments exist over what becomes the long-term and design decisions have long-lasting implications and effects. Mechanist and Organicist Perspective: Two recurring ways of looking at the ‘control’ of urban development consistently reoccur in the literature – the mechanist view (the city-as-machine) and the organicist view (the city-as-natural-process). In the mechanist view, society is, or can be, consciously planned, designed or otherwise created by human hand: it is a machine that is knowable and thus controllable. In this view, the market is primarily a relatively static machine for resource allocation. The mechanist view has parallels with both modernisation and Modernism. The organicist view, prevalent prior to the twentieth century, sees society as a selforganising process – that is, as a dynamic and adaptive process in that systems acquire and maintain structure and that no external agency controls. It defies human control and is, at best, moderately tameable. Incremental Change: The essence of the organic view is incremental change. The incremental change happens over a period of time with the efford of a number of persons.
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|Temporal Dimension Summary Small scale, incremental change relates to evolutionary change. Evolution shows how radical change can happen through incremental change. For example, Pedestrianisation of Copenhagen happened incrementally at a pace that allowed people to adapt and respond to the change. In large-scale development, ‘mistakes’ have to be eliminated because they are much more difficult to correct later. Urban development should be a process of sequential adaptation. The Part and the Whole: While incremental change is desirable, there is a need to ensure that the incremental steps add up to larger wholes: natural systems are able to do this because they are self-correcting systems. Urban form arises from the interactions of many designers over time and thus one not only designs a building, landscape or infrastructure, but also contributes to the emergent character of streets, neighbourhoods, towns and centres. Two levels of control are perhaps necessary –
at a more strategic level, and involving the design of a framework or ‘armature’ (the ‘whole’) at a more detailed level and involving the design of the ‘parts’.
A place vision or design framework can provide strategic coordination, but it must also retain sufficient flexibility to accommodate underlying and evolving processes of change, and also to allow incorporation of the ‘better idea’. Large Lum Developments: The historical trend towards large-scale growth and away from smaller-scale, incremental growth has also led, in some places, to an increasingly controlled and monotonous urban fabric – lacking the diversity, character and experiential depth of places that have developed incrementally. Large lump developments in all their forms have the potential to address issues of place-making – at least initially – in a coherent and joined-up manner and, in particular, to fund the provision of major new elements of the capital web, including new urban spaces Larger developments are typically organised into a series of smaller development projects to be implemented over different time frames, each by a different building developer and perhaps also by a different designer, thereby allowing a range of inputs and contributions, and, once built, a diversity of owners.
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|Temporal Dimension Summary Continuing Evolution: Once completed, large developments must be able to change incrementally. The ongoing single control regime of large lump developments may be stultifying and – lacking the internal capacity and stimulus for creativity, innovation and development – may only be capable of (slow) managed decline. While large lump developments often need land ownership to be consolidated to allow development to proceed, to allow subsequent change to occur incrementally that land ownership may need to be broken down. CONCLUSION: The temporal dimension of urban design focuses on understanding the implications and impact of time on places. Time involves change – both that which happens in cycles and that which occurs in progressive, unfolding and irreversible ways. Change itself both responds to and shapes further change. Urban designers need an awareness of potential change; to understand how places change over time and be able to anticipate the impacts of actions, how and why development will occur and even how materials will weather; the series of opportunities and constraints that may arise; and how change can be managed. Lastly, to be robust and sustainable, environments need to be capable of evolution and incremental change. The development, control and communication processes in urban design has also been discussed.
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