INTRODUCTION
Urban areas are remarkably different from rural environment and they pose enormous challenges to environment professionals in terms of what form they should take. In general terms, various theories, concepts, and approaches have been employed in solving urban problems but an integrated approach has rarely been employed.
Thus professionals like urban planners, architects, engineers and others often work alone as is urban design problems can be solved independently of each professional’s efforts. In recent times, the trends is now towards multi-professional approach.
Thus design challenges are taken up from environmental and sociological perspectives, decision-making process is more open and participatory, while the state (politics) and the market (economics) are becoming more critical in the implementation of design projects.
Concept and Scope of Urban Design
Urban design focuses on planning and design of activities of urban environment at a more detailed level. The urban environment invariably is a highly modified environment in which various components such as residential, commercial, recreational etc must be carefully designed to meet the highest degree of human comfort and functionality attainable.
The urban environment to be created is dependent on the natural qualities of landscape on one hand, the common cultural attributes prevalent in the area and the skills and orientation of professionals involved. In recent times, urban design is being conceptualized in terms of determinism, possibilism, and probabilism in recognition of the critical role which the natural environment plays in the final form of an urban area.
Urban design is a combination of urban planning, landscape design and architectural design.
Urban design is specific in scope and includes laying out of roads buildings and other urban elements with regard to efficiently and visual effect.
Urban design is an aspect of physical planning design which relates structural development with the environment.
It is an intervention in the structure of the built environment aimed at creating high quality, people friendly and visual viable environment. The term urban in this context is a wide and all embracing meaning including not only the city and town but all built environment the village and hamlet.
Design also in this context does not only mean activities such as sketching, planning, arranging, coloring and pattern making but includes evolution of effective problem solving proposals and the process of delivery in organizing development.
Objectives include: creation of an environment with its own identity or character, creation of places where public and private spaces are clearly distinguished {A place of continuity and enclosure}, creation of a place with attractive and appealing outdoor areas. A place that is easy to get to and move through {Ease of movement}, a place that has clear image and easy to understand {Legibility}, a place that can change easily {adaptability}, and a place with variety and clarity {Diversity}Lynch, {1981}cited in Matthew and others {2004}identified five performance dimension of urban design to include:
Variability: The degree to which the form of place supports the functions, biological requirements and capacities of urban design.
Sense: The degree to which places can be clearly and structured in time and space by the users.
Fit: The degree to which the form and capacity of spaces match upto the pattern of behaviour that people engage, can, or wants to engage in.
Access: The ability to reach other persons, activities, resources, services, information or places including the quantity and diversity of elements that could be reached.
Control: The degree to which those who use, work or reside in places can create and manage access to spaces and activities.
Urban design can also be referred to as a product or an outcome to various processes. It is for example variety a product (the design of the created environment), intervention into a process (e.g. land or property or real estate development process and a process itself i.e. the design process.
Urban design is a creative, analytical and problem solving activity through which objectives and constructs are weighted and balanced, the problem and positive solutions explored and optimal resolutions derived. The process should also add value to the individual corporate parts, in such a way that the whole is greater than the sum of the points.
Modern urban design is generally more expensive as it is concerned with the quality of the public realm both physical and socio-cultural and the making (and managing) of public places for people to enjoy and use. It may also be one to achieve conveniences of the urban experience and identifies principles by which urban environments can be modified.
It is an interface between architecture, planning and related profession.
Urban Design Elements
Rewie (1972) summarizes the basic elements of urban design into four major headings namely; living, working, playing and moving elements. These elements constitute major land use elements in urban design.
1. The residential element: Areas of all kinds including private and public housing estates and other concomitant developments. They include gardens, publicly organized open spaces, children play areas other complementary uses like: local shops, churches, mosques, and other community buildings like fire and police stations, health centres etc.
2. Employment places: Where people work such as agricultural centres. Some of which include: farms, markets, factories, mine centres, offices, central business district, central and regional shopping centres.
3. Recreational Places: These are areas where people play and spend their leisure time. they include sea sides, sports grounds, cinema halls, theatres, restaurants, cafes, club house and etc.
4. communication: Element that promotes movement of people and goods. It includes: roads, railways, waterways and associated infrastructure such as airports, seaports, bridges, transmission cable and pipelines.
All of these elements within the context of urban design can be treated in isolated within the built environment. Considerations in urban design is not the land use arrangement per se but the structural arrangement to varying sub-components as listed in 1-4 above in a visually appealing and functional manner.
Process of urban Design
Urban design presentation requires artistic impression, of creativity and is also problem solving. Urban design as an aspect studio work is research oriented; as such it is a process commences with:
i. Problem identification: Problems within the built environment are envisaged, disserved and conceptualized. This problem must be within the range of the identified elements. These problems may include: problem of movement, traffic congestion, vista and legibility problem.
ii. Formulation of goal: The goal of the design is set in all cases. They are set in conjunction with clients and stakeholders.
iii. Data and information gathering: Necessary data and information at this stage are gathered and analysed. This will allow for visioning, and mergence of possible solution to the identified problems.
Personal experience of the urban designer may also contribute to the emergence of better design philosophies.
iv. Synthesis and prediction: Solution proffered are subjected to test or evaluation.
v. Decision Making: At this stage decisions are made on the alternative available, on which to be discarded, and those that should be retained for further evaluation and final acceptance of the best alternative.
Goal of Urban Design
Whether the designed environment is a commercial, institutional, or residential one, three basic purposes must be fulfilled. These are COMMODITY, FIRMNESS and DELIGHT.
COMMODITY in urban design implies the functional goal of the design-what is the structure or complex to be used for? Is it to provide decent, affordable accommodation for low income earners as is the case in low cost estates.
FIRMNESS refers to permanence or structural integrity of the building or complex i.e will it last. This reflects on the type and choice of various components of the structure e.g the Eiffel Tower in France and the status of Liberty in the USA which are fine examples of the “grand design tradition” of the contemporary urban design.
DELIGHT entails everything relating to the aesthetic considerations in the-built environment. The considerations may include colour, shape, size, texture and appearance of urban design elements. It may also influence urban design options, for instance whether to preserve, modify, or accentuate certain quality of the natural and built environments under consideration.
Different urban designers may emphasize these interrelated dimensions in varying degree. However, each of them must draw on his professional expertise in order to face the challenges of the specific design. This endeavour is not necessarily carried out as a lonely task. There is always the need for urban designers to collaborate, both with other professionals and with the eventful users of a design.
In order to respond to these concerns effectively, urban designers must draw upon and accumulation of data and ideas organized as theories and models.
THEORETICAL APPROACH TO URBAN DESIGN
Theory provides a source of information to which designers can refer simply because it is a system of organized ideas that describe or explain the real world. Distinction can be made between Positive Theory and Normative Theory.
Positive theory tries to discover predictable relationships between variables, in this instance, the effect of modifications of the physical environment on commodity, firmness, and delight. Normative theory, on the other hand, is based upon value-laden descriptions and explanations of what ought to do done. Normative theory may express itself in design manifestos, identification with a particular design movement, other differences in style.
Taking positive theory further, one can distinguish between procedural and substantive issues as regard urban design. The “procedural” refers to the methods of gathering data or making decisions, while the “substantive” refers to series of useful facts about the relationship on one hand and the ability of a design to provide commodity, firmness and delight.
ASSUMPTIONS OF URBAN DESIGN
The urban design process is a complex activity of information-gathering and decision-making. The planning and implementation of designs are often hinged on several basic concepts. Two of such concept with strong bearing on urban design include CONGRUENCE and CAPITAL ALTERNATIVES.
CONGRUENCE is a major goal of the urban design process and relates to the degree of ‘fit’ between the needs and preferences of users and the features of a given setting. The primary emphasis is on the match between form and function. For designs to be congruent therefore, they must support or facilitate the desires and needs of the people using them. A great deal of congruence can be achieved in urban design through flexibility which ensures that spaces can support a variety of activities simultaneously.
CAPITAL ALTERNATIVES is the concept that permits our adaptation or adjustment to the physical environment. Where available design alternatives are few, we will most likely have to adapt to current conditions, which may be costly in some cases (both environmentally and economically). However, when many alternative designs exist, we are apt to adjust environmental conditions through one means or another. As such, the various combinations or isolated uses of design elements, such as furnishings, lighting, colour or arrangement of spaces, all indicate design alternatives. In a particular setting, many design alternatives may exist, but as various criteria are brought to bear, more and more alternatives will be ruled out.
The process by which we determine the proper design alternatives and weigh the importance of various criteria forms the heart of the design process. This is a complex undertaking, since there are many interrelationships among different social, economic, artistic and cultural pressures that affect it. Many models of the design process exist with basically similar components. One of such models is discussed below.
THE DESIGN CYCLE
The design process essentially begins with an awareness both of needs that have been met, and of potential design alternatives (environmental adjustments). Once a need and possible design alternatives have been specified, it is necessary to develop criteria for determining how effectively the proposed alternatives resolve the need. Although criteria may be physical in nature, other variables will be put into consideration. More often, evaluation must be performed in order to know whether specific design alternatives measure up to the criteria established for them. When such evaluation indicates desirability of a particular alternative, additional steps must be taken to ‘implement’ the design. Models of the design process that stress cooperation among different professions, consideration of environmental quality and post-occupancy evaluation (POE) can be effective tools in going beyond this step and arriving at the goal of a habitable environment. The specific steps in the design cycle include Programming, Design, Construction, Use, and Diagnostic Evaluation.
Step 1-Programming
It is the take-off stage when ANALYSIS is made of the existing environment in a comprehensive manner. Here, design goals and objectives are clearly identified based on reliable data. Possible constraints that have to be overcome are investigated while performance or design criteria are established. This stage is critical and is done within the context of the prevailing physical environmental attributes, users behavioural characteristic, financial and technical resources available and the expected end product-what the final built environment should look like.
Step 2-Design
Based on clear understanding of users needs and expectation, the available data will be SYNTHESIZED. This will permit making designs decisions that satisfy criteria. Many criteria can be established, and one of them is the performance criteria. The performance dimensions may include vitality, which is an anthropocentric criterion; sense, which is the degree to which the designed environment can be clearly perceived and mentally differentiated and structured temporally by the users; and fit, the degree to which the form and capacity of spaces, channels, and equipment in an environment match the pattern and quantity of actions which users customarily engage in.
Other performance dimensions are access, the ability to reach other activities, services, persons or places; control, which is the degree to which the use and access to spaces and activities, and their creation, repair, modification and management are controlled by users of the built environment.
Step 3-Construction
This step in the design cycle refers to the building of the project and modifying plans under changing constraints. This can be regarded as the ‘Realization’ stage where the existing built-environment or the natural landscape is extensively modified. the primarily focus is to translate design components into reality and will require meeting design challenges that are not initially anticipated or foreseen.
Step 4-Use
At this stage, ‘Reality Testing’ begins in which the end-users move in and adapt to the environment. As discussed earlier, the ultimate purpose of urban design is to attain commodity, firmness, and delight and this can only be ascertained when the designed environment is actually put to use.
Step 5-Diagnostic Evaluation
This is the ‘Review’ stage in which the final product is monitored in terms of objectives and use. This ideally translates into future design criteria as the ‘gap’ between reality and expectation will manifest and provide new challenges which urban designers will have to face.
This model of design process is a continuous cycle such that the ultimate product of urban designs is not that is accomplished and done with at once. Rather, it is one that constantly responds to changing criteria which are physical, environmental and sociological.
SITE ANALYSIS IN URBAN DESIGN
Each subject site is unique in terms of many defining attributes-both natural and manmade. The essence of site analysis is to identify those attributes that represent potentials to be consolidated as well as constraints to be overcome.
Site analysis therefore involves detailed, meticulous identification and evaluation of prevailing characteristics of an environment, whether built or natural. Attributes of site to be analysed in urban design will include the following:
NATURAL ELEMENTS
i. Topography: The general nature of the physical setting of a site as characterized by the terrain, whether plain or undulating; the existence and type of rocks, the slope characteristics, and the geological nature of the whole site.
ii. Soil: This is the topmost layer of the landscape on which subsequent design activities will take place. The soil is analysed in terms of its texture, moisture content, degree of fertility, load-bearing capacity, porousity and so on.
iii. Drainage: An analysis of a site’s hydrology is critical in urban design.
The site is analysed in terms of its drainage system, main rivers and tributaries, volume and velocity of flow, seasonality as well as direction of flow. Water resources are carefully identified, such as ponds, lakes, springs, brooks etc.
iv. Vegetation: The presence or otherwise of plant elements is equally vital in analysis of any site. The vegetation will be studied in terms of types, colour, height, appearance, seasonality, smell, medicinal value, canopy spread and other characteristics of trees, grasses, flowers, shrubs etc available on a site.
v. Climate: The element of climate to be examined will include amount and intensity of rainfall, temperature characteristics, wind conditions and other climate-related elements which influence design.
vi. Sunlight: The direction and intensity of sunlight as well as seasonal variation should not be over looked. This is because sunlight shows strong influence on the orientation of urban elements such as playfields, classroom buildings etc.
vii. Wind: The velocity and direction of prevailing wind on a site cannot be over looked because of natural ventilation requirements and the ability of wind to disperse environmental nuisance among others. As a result, wind analysis becomes necessary for relative positioning and orientation of urban elements. For example, waste dump, polluting industry, and residential blocks should not be aligned in the same wind path.
Man-made Elements
Buildings Analysis has to be made of existing structure, especially in built-up environment. Such analysis will inform on building type and use, physical conditions, relative location of structures, set-back and air spaces, height, architectural styles, materials of construction, and age among other characteristics.
Facilities These include health, educational, recreational and other social facilities that may be present. Analysis is made of these elements in terms of their location, site and physical conditions, level of utilization, adequacy, and spatial efficiency.
Utilities An analysis of water, electricity, telecommunication, waste disposal, storm drainage provision is equally important. The location and distribution of ancillary and basic structures, their capacity, network pattern (spatial efficiency) etc must be noted.
For example, location of transmitters, transformers, flow stations, main, size of drains, disposal bins, transfer stations etc cannot be overlooked.
Circulation The system of roads, streets, and walkways must be examined as various components of the urban area have to be efficiently linked together. Characteristics to be investigated will include hierarchy, width, pavement materials durability, physical state, connectivity, level of service, and ancillary furniture provided on these circulatory components.
Views Analysis here will involve the identification of pleasant views to be preserved and unpleasant views to be screened or improved upon.
This involves visual analysis determining the sources and types of visual nuisance, its intensity, and duration etc.
Closely related to this is aesthetic consideration involving analysis of the streetscape and the landscape for environmental beauty. The elements conferring the aesthetic quality will be noted such as historic structure, exotic vegetation, and outstanding architectural style and so on.
OTHER CONSIDERATIONS IN URBAN DESIGN
Urban areas made up of specific but interdependent elements such as residential areas, city centre, industrial estates etc. Their urban design challenges revolve around three major considerations, namely: specific functional components, circulation or interaction (linkages) between these components, and the form or the final appearance of the urban elements being designed.
The components refer to the various parts of an urban assemble which enables it to meet the needs of users. For example, a well designed residential estate has as its components such things like serviced plots, shopping mall, places of worship, play ground and green areas, medical facilities and so on. These are required for the residential area to perform the basic function of providing decent accommodation to the end-users.
Linkage in urban design relate to how various parts of an urban assemble are located relative to each other for efficiency, and the means by which the linkages are effected. Where the various parts are optimally located, functionality and utility level will improve dramatically. Complimentary activities are carefully agglomerated while conflicting activities are segregated. yet they must be planned to interact and function as a harmonious entity. Circulation facilities in the form of roads, walkways, pedestrian bridges and under passes are integral part through which the site is transformed to meet the design goal of the urban assemble under consideration.
Form or the overall physical appearance in terms of whether the structures will be predominantly vertical or horizontal or a mixture of the two is the final consideration in urban design. The final form is determined by a number of factors but must compliment, rather than conflict with the natural landscape.
As an example, residential structures may be deliberately vertical in hilly terrain to achieve an overall form that competes, rather than succumbs to the visually domineering landscape.
In the design of the various urban elements, these three considerations are carefully integrated within the limits imposed by site characteristics, the needs of the end-users, and the professional skills of the various designers.
