4. Detailed design development
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The second stage in the preparation of a project is detailed design development. This will result in a final master plan, outline building designs and cost estimates. The overall design process is shown in Figure 6.
The second-stage designs will provide the basis for the evaluations undertaken in the third-stage feasibility study, which may lead to design modifications. The second and third design stages are, therefore, to a large extent interdependent and can be carried out in parallel. Both stages will rely on the collection and analysis of survey data, particularly of the actual volumes of produce traded.
Processing and analysis of initial surveys
The first step in preparing a detailed design will be to undertake and analyse the surveys which were outlined at the end of Chapter 3. Apart from surveys of existing facilities and engineering investigations, the most important of these will be the surveys of produce flow (see Chapter 11).
Roadside surveys. These surveys should, ideally, be undertaken over an extended period, covering all produce flows into a city (including both wholesale markets and retail outlets). The best method, if resources are available, is to carry out a complete roadside survey, using fixed checkpoints. However, as such road-blocks are often also used to control "illegal" trade and to extract gratuities from traders, the traders may be reluctant to cooperate in providing accurate information. The agreement of municipal authorities and police to assist in the surveys may also be difficult to obtain
As well as quantifying the volumes of produce flow, roadside surveys provide useful data on the transport modes used by farmers and traders, including the key role often played by public transport. The surveys should provide an understanding of how the existing marketing system operates, including the roles played by the various functionaries who are participating in the marketing channels and the origin and destination of produce flows. More details of the types of analysis that should be undertaken are provided in Chapter 12.
Figure 6 Stage 11- detailed design development
Estimate of demand and trade volume. The next step is to make a detailed projection of the potential demand for produce. In preparing the demand estimates a series of assumptions will need to be made. There are a number of models used by economists which take account of income-elasticity coefficients, relating changes in income to spending behaviour. Because of lack of data it is rarely possible to use these techniques and reliance usually has to be placed on estimates of present supply, matching these to available data on per caput consumption of fruits and vegetables. Using this approach the substitution effect between different produce is assumed to be zero.
Per caput consumption. Consumption data should ideally be derived from detailed local nutritional surveys of the daily intake of fruits, vegetables, fish and meat, for a range of income groups. From such surveys, estimates can be made of annual consumption, which is expressed in terms of kilogrammes per head (or "caput") of population.
FAO has undertaken regional food balance sheet studies of per caput consumption, taking into account factors such as production levels, imports, exports and processing requirements (see Chapter 12). These are likely to be the most easily available data, but need to be used with some caution as the figures are national averages. They tend to disguise substantial variations in consumption between different seasons, locations, income groups and between urban and rural areas, particularly if there is also a large tourist trade.
Detailed estimates of physical requirements
Before the preparation of an outline master plan it is necessary to ensure that there is sufficient space at an existing or proposed market site to accommodate the range of facilities required for the operational procedures envisaged.
Throughput The first step in this procedure is to make projections of the likely throughput of the market. A simple approach to projecting throughput is to develop scenarios for the peak monthly throughput of the market based on estimates of demand at specific design dates for the likely population to be served, using projections from previous studies of population growth and migration trends.
At least three possible design scenarios should be developed for a range of design populations. The first should be a minimum size, corresponding to present immediate demand and based on the results of roadside surveys, if available. The second should be a size corresponding with likely demand in the near future (say within 5 years) and the third an ultimate size which would accommodate the growth in demand over the expected life of the market (usually taken as 20 to 30 years).
Estimating assumptions. In making throughput projections, two key assumptions need to be made. The first is the extent to which peak production and the sales of fruits and vegetables could vary by season. A peak season may be as much as 2.5 times the annual monthly average and perhaps 5 times as much as the minimum month. Second, the percentage of the wholesale trade going through the market will also vary depending on the operation of existing marketing channels and how they might realistically change in the future.
Data from roadside and retail surveys will provide a basis for establishing these factors, but the data should be treated with some caution as they may not be representative of the whole year. The figures are also likely to be overestimates, as not all produce reported as being traded is actually sold and substantial losses are likely to occur. This does not affect the input volume, as the market must still be designed to accommodate it. However, any calculations that use output volumes (such as retailers' parking requirements) may need to be adjusted to reflect this. The overall output trading volume should therefore be reduced by say 5 percent.
A reasonable throughput target for when a market is fully operational should also be projected. However the extent to which trade might switch from present markets and other channels, such as direct sales to supermarkets, must be evaluated carefully. This is essential bearing in mind the degree to which some produce will by-pass the market system, particularly that from home gardens within the city. The volume of this trade will not appear in roadside surveys, but will form part of the overall per caput consumption. A conservative basis for planning, commonly applicable when existing markets are not going to be closed down, is that a new market will gain the new trade and existing markets and other channels will broadly retain their present level of trade. In that case the 1st phase of a new market could be sized to meet an initial (5 year) growth.
Space requirements. In estimating space requirements for markets very simple techniques should be used. Two estimating methods can be adopted, which are explained in detail in Chapter 13:
· an approach based on overall annual through-put. A range of 10 - 20 tons per square metre (mē) of covered sales space is desirable;
· an approach based on the "ideal" space standards that need to be allocated to accommodate the various activities required to handle the average (or in some cases maximum) daily throughout of commodities.
Figure 7 Diagrammatic layout of typical wholesale market
There is usually a reasonable degree of agreement between these two methods. The estimates provide a basis on which to allocate floor space for the primary, commercial or sales activities that will be undertaken in the main market buildings. These activities would include the unloading of produce, its display by producers or traders, its sale to wholesalers (by private treaty or auction) and its short-term storage and display by the wholesalers before being sold and dispatched to retailers.
Simple assumptions also need to be made about the space requirements for ancillary uses, such as offices, additional storage, and other facilities. A crude rule-of-thumb basis for estimating this would be to allow 50 - 100 percent in addition to that already estimated for the main commercial floor space.
For a recent FAO study in Thailand long-term wholesalers' stores (including cool storage) were assumed to require an additional space equivalent to 40 percent of the commercial sales space. However, this figure may vary quite radically. One extreme might be a secondary wholesale market in a rural area where the market's essential function is to assemble produce for immediate despatch (in which case virtually no long-term storage is required). At the other extreme might be an urban terminal market, without auction facilities, which provides a large amount of medium to long-term storage (possibly including cold stores) for produce such as onions, potatoes and fruits.
Washing, packing and grading might require additional space of around 1mē per ton of throughput. Offices for market management staff (whether private or public enterprise) and for basic support facilities (such as security and toilets) will each need an area equivalent to at least 5 percent of the commercial sales space. Other facilities, such as banking, post offices, extension services and farm input sales will need a further area of around 10 percent of the commercial sales space.
Outline master plan
An outline or draft master plan is a physical representation of a market's development programme, broadly setting-out the space and circulation requirements related to an existing or proposed site. I he plan will be very diagrammatic at this stage, as illustrated in Figure 7.
The purpose of preparing the plan is to provide a basis for the consultations which will be needed to develop the project further at the feasibility and implementation stages. Adequate time must be provided at those stages in order that full consultation can occur and potential design conflicts can be resolved. The plan also provides a rationale for the approximate cost estimates that are used in the financial and economic analysis described in Chapters 5 and 10. A background to the planning process and further details of typical planning criteria are discussed in Chapter 13.
Function of the plan. The main function of a plan must be to maximize the throughput of a market, providing the most efficient access and traffic circulation system, whilst minimizing costs. The success of a plan in the long term will depend on whether it allows the market's users to mould and adapt the market to their particular requirements. Although the influence of a site is important, the essentially functional nature of markets leads to compact and regular layouts, using standardized building forms and also resulting in lowest development costs. Architectural quality is not of paramount interest but should not be forgotten, as through geometry and landscaping the layout will provide a visual clarity to the users and, if properly considered, will relate the market to its surroundings, ensuring that it provides a positive contribution to the built environment.
Planning and land use criteria Important factors to be considered in preparing an outline plan are how the construction of the market might be phased and the extent to which separation of more permanent uses from those which are of a transient nature is needed, so that future growth and changes can be accommodated without disruption.
As roads and parking areas are a major part of total capital costs and are elements that can be varied substantially in both extent and standard of construction they will be important in determining the outline plan. The key issue will be to evolve an arrangement with a satisfactory relationship between the site access, the internal circulation system, unloading and loading areas, general parking and the main market buildings.
After preparing the draft plan, the distribution of land uses
should be reviewed. As a rough rule-of-thumb the portion of the
site covered by buildings should be around 20 - 30 percent, road
space and parking between 50 - 60 percent and other uses,
including drain reserves, some 10 20 percent of the total area.
Examples of the distribution of land uses are given in Chapter
13. Values for land uses at a typical small scale terminal
market (Kalimati market, Kathmandu, Nepal) are as follows:
|- Buildings||6 060||29.8|
|- Farmers' market area||710||3.5|
|- Roads||5 955||29.2|
|- Parking areas||3 570||17.5|
|- Footpaths & landscaped areas||3 495||17.2|
|- Drainage & other reserves||580||2.8-|
|- Total site area||20370||100.0|
Access and circulation. Markets obviously need to be located adjacent to main highways, but a direct approach off a heavily used route or close to an intersection could cause problems. These problems will become more difficult with future traffic build-up, thus making planning approval unlikely. The layout, therefore, should have its own segregated access.
Within the market, incoming produce should also be strictly segregated from outgoing. The usual technique is to adopt a one-way circulation system using a continuous peripheral road, with the main buildings located within the centre of the block. An advantage of this approach is that it enables drivers to search for parking spaces and to correct mistakes. As a basic principle it is also desirable to avoid cross roads within the lay-out. To reduce the number of conflict points as many of the junctions as possible should be T-junctions (3-way). If cross roads are essential they should be created by using roundabouts (rotaries)
One of the most difficult features to achieve in any market-site layout is to obtain sufficient road length al the site entry so that incoming trucks can slow down and be checked-in at the entry-gate without causing backing-up onto the public highway. 'I his problem also occurs on leaving the site. A layout with more than one exit would have obvious advantages in terms of traffic control, although this may create problems of extra staffing for security, the collection of lolls and the management of sale documentation.
Parking. The turnover of vehicles in a market, particularly those of retailers is rapid and it is desirable that parking spaces are generous. A minimum of around 32 mē per truck parking space should be used, excluding the main circulation. As a general rule an overall standard for the provision of parking places (trucks, pick-ups and private cars) of 3 spaces per 100 mē Of sales area is reasonable. This should also allow unloading and loading facilities to be directly adjacent to the main market building. For peak periods, however, this needs to be increased to around 5 spaces per ]00 mē, which may require the provision of an overspill parking area a little remote from the market facilities. More elaborate methods For estimating parking requirements are given in Chapter 13.
Figure 8 Comparison of types of wholesale premises
Engineering services Engineering services other than roads need not be considered in any detail at this stage but, as the site layout is gradually defined, consideration will need to be given to the location of other service networks. In tropical areas, because of the scale of open drainage systems and the significant run-off from paved market areas, surface water drainage is likely to be the most important service to consider.
The majority of other services are likely to be placed underground, but these networks need to be coordinated with each other for ease and economy of construction and in order that future maintenance does not disrupt the working of the market. The easiest way to understand the distribution of services is to prepare a series of typical cross sections, which resolve both the vertical and horizontal relationship of the services. Engineering services are summarized al the end of this chapter and discussed in detail in Chapters 13 and 14.
The type of buildings that the market might accommodate needs to be considered at this stage in the design because it will affect the site layout.
Types of market but/dings. There arc four basic types of market buildings which can accommodate the main commercial floor space. The choice of an appropriate type will depend on the operating system and method of sales to be adopted at the market. Figure 8 illustrates the basic types in cross-section, using the same roof form so that comparison is simpler:
i) garage type
With this type of market premises the wholesalers' stalls run the full depth of the building, with access platforms on both sides. One side (3 metres width) is sometimes used for unloading from rail wagons, while the other may be wider (say 7 metres) and used for both unloading and loading into trucks.
This type of building is suitable for the sorts of large-scale wholesalers found in North America and where retailers use large trucks, typically with pallet loading.
ii) back-to-back type
This is a variant on the garage type, the essential difference being that it has a central wall dividing the wholesalers' premises. By varying the position of the dividing wall, different sizes of premises can be obtained. Only one access point is provided for the purchase, display and sale of produce as these activities normally take place at different times of the day. It is usually better if the platform is at the same level as the road if the majority of the market users have small pick-ups, cars or animal carts, or if larger trucks with side-loading are going to be used.
This type of premises is an ideal form for medium and small-scale wholesalers and is particularly suitable for developing countries. The building type can be either used as the point where the purchase of produce is made from commission agents and traders on a private treaty basis or can be used in conjunction with a separate auction hall. A variant of this building type, used in Amman, is to construct a single depth wholesalers' premises backing onto a boundary wall or fence. This makes very effective use of the site area.
iii) central spine, with buyers' walk
This is similar to the back-to-back arrangement but also incorporates a central buyers' walk which facilitates the appraisal of produce by buyers. The buyers' walk is typically 4 metres wide, such as at London's New Covent Garden market, with unloading and loading of produce confined to the rear of the premises.
Many West European countries (such as France and Spain) have adopted this type of premises, but its use in other countries, such as Brazil, has not been entirely successful. In some cases the buyers' walk is made much wider (more than 16 metres wide in the Paris Rungis market) to allow a wider display of produce and the easy movement of produce to retailers vehicles. Recent public health trends have, however, tended to discourage the entry of vehicles into the covered sections of market buildings, particularly where they trade in meat or fish products.
iv) central spine/ball-type market building
This is an integrated facility where the sale of fruits and vegetables is undertaken in a multi-purpose shed. The typical facilities might include producers' sales space, a buyers' walk, wholesalers' storage facilities (often enclosed in steel cages) and, where applicable, an auction hall. Levies on produce sold would be collected at one or more sales counters, where security facilities might also be accommodated.
The building illustrated in Figure 8 is of a limited depth and would be suitable for medium and small-scale wholesale markets in developing countries, particularly as it could be relatively simply converted, if necessary, into one of the other types. Some hall-type markets are of a much wider span, such as in Milan, (Copenhagen and some Japanese cities. Although convenient for major cities with small-scale wholesalers and many retail customers, this building form is not necessarily appropriate in developing countries because of the high cost of the roofing system and the potentially greater internal handling costs.
Compact site planning. Whatever type of premises is selected it is important that a consolidated layout is created rather than a scatter of smaller unrelated buildings. The sales spaces should be grouped together, probably only segregating the larger wholesalers, as their building requirements will tend to be different, The distance between buildings should be determined by "ideal" dirnensions for parking and circulation (see Chapter 14). An approach based on grouping of facilities has distinct advantages:
· the site is easier to manage, particularly if an auction system is used;
· the security system can be simpler;
· safer site circulation, with minimum crossing traffic and road lengths;
· flexibility in use, allowing seasonal variations in commodities to be accommodated and allowing adjustments to be made between wholesalers' premises, auction spaces and other uses;
· ease of routline maintenance, cleaning and solid waste collection;
· fuller building utilization at any one lime, with few redundant spaces;
· concentration and economic provision of building services; and
· greater weather protection for both the produce and market users.
Multi-storey market buildings. Market buildings with the sales space on more than one floor should, unless absolutely necessary, be avoided. Only offices for wholesalers, commission agents or brokers and other uses not involving the transfer of produce should be accommodated at a mezzanine level if there is insufficient space on the ground floor.
Non-horticultural produce markets. Fish marketing is usually undertaken in a separate building, the plan organization of which can be similar to that of a central spine type building. Construction would normally be to a higher standard, particularly in the provision of easily cleanable internal (wall and floor) finishes. The building should be provided with facilities for gutting, cleaning and boxing, with a cool room for the temporary storage of fresh fish and a freezer room for frozen fish. It is preferable that a fish market has its own quality- control facilities, perhaps at mezzanine level, overlooking the sales space.
Separate facilities must also be provided if it is envisaged that the market will also trade in poultry, eggs, grains or meat. Accommodation for meat marketing can be virtually identical to that for fish except that it is preferable that ceiling mounted rails are also provided for the easy transport of carcasses. Flowers are often marketed in the same building as fruits and vegetables, but can be separated if the turnover justifies it or in more temperate climates where some form of heating may be required.
Market authority building. The site should be administered by the market authority from a central service building, which might be of more permanent multi-storey construction, sometimes physically linked to the main market buildings. The scale of facilities will vary depending on the size of the market, but typically this building might contain an agricultural inputs unit, one or more banks, a post office and public telephones. The market authority offices should ideally be located at first floor level, overlooking the whole market. Depending on the scale of the market, their accommodation would comprise an account's section, a general office, a director/manager's offices and a board room.
Even where the market is to be operated by private enterprise it will be essential to provide facilities for the public bodies concerned with marketing and public health Such facilities might include a hall for public meeting and exhibitions, accommodation for market information and extension services, an emergency clinic or first-aid post, an environmental health laboratory and a weights and measures office.
Ancillary site facilities. Provision should also be made on the site for public toilets, building maintenance facilities, centralized solid waste collection and crate storage. An entrance control gate will be required, including in most cases, a weigh-bridge. This will normally be combined with the site security facilities. Simple produce cleaning, grading and packaging may also be needed if this has not been undertaken at the farm level or at collection centres located in the production areas.
Other facilities that might be provided are a petrol filling station, a staff canteen or tea shop (although these could be limited if adjacent commercial areas contain adequate services), a creche for mothers working at the market and small-scale religious facilities (shrine, chapel or mosque).
Hostel accommodation might also be needed for farmers and hauliers who are obliged to remain in the city overnight or for out-station market staff who might come to the city for on-the-job training.
Facilities for retailing. Retail units for the sale of packaging materials are normally required at a market but the provision of other types of retailing facilities is a difficult issue to resolve as it will tend to interfere with the operation of the market. One possibility is to provide a limited number of semi-retail shop units for the sale of specialist food stuffs, such as herbs and spices and speciality fruits. This would only be an attractive proposition at a secondary wholesale market if it enables buyers or wholesalers to purchase goods they would normally want to buy anyway on a "one-stop shopping" basis. Terminal wholesale markets sometimes also include "cash and carry" facilities so that retailers can buy non-horticultural food stuffs in bulk at the same time that they are making other purchases.
Traditional marketing practices and land-use restrictions may dictate that a wholesale market has to operate alongside a retail market, in which case they should ideally be managed as one unit, but should always be physically segregated.
Farmers' markets. Another common issue is whether a market should support an associated farmers' retail market, where producers could sell to retailers and consumers. This would also enable producers who have not managed to sell their produce to wholesalers in the main market to dispose of their surpluses. The strong argument against this is that selling directly to the public in the farmers' market at times of oversupply, when prices weaken, will be in direct competition with the wholesale market. With an auction hall, for example, the possibility that supplies might be withdrawn for sale direct to consumers could have a disastrous effect. On balance, it would be better if this practice was discouraged, unless confined to sales only to retailers and strictly controlled (for instance by only allowing trading after the end of the main working day).
Specialist services. A recent trend, particularly in the USA, has been to provide a wider range of specialist facilities on market sites so that they operate as food centres, under a single management system.
Figure 9 Studies of building form - Kalimati market, Kathmandu
Long-term wholesaler storage facilities (usually for fruits and incorporating chill rooms) and banana ripening rooms are frequently incorporated within a market, often with some arrangement for financing by private enterprise, the market authority providing the land for the building and a share of the main infrastructure.
Animal slaughter, food processing, pre-cooling/drying facilities, cold storage and ice making plant may also be accommodated. These again are normally financed by private enterprise and should always be justified on the basis of a separate financial and economic analysis from that of the main market buildings (see Chapter 10).
Caution is required in appraising the need for these facilities, particularly their scale and technical specification. Optimum refrigeration conditions in cold stores, for example, are often less important than flexibility in general operating efficiency which can result in much higher utilization rates. Another common error is to assume that facilities will operate on a high technology basis, such as using pallet storage and fork lift truck loading and unloading. This may not be valid or appropriate where maintenance is poor and labour costs are low.
Figure 10 Final master plan of Kalimti wholedsale market, Kathmandu
The choice of suitable building forms and materials for different types of marketing facilities is part of the detailed design process and is discussed in Chapters 13 and 14. Figure 9 illustrates the type of output that would be expected from studies of building form. In preparing the detailed building designs the following factors will need to be considered
· space standards and design modules
· external climatic controls and internal servicing requirements, including ventilation and natural/artificial lighting
· overall building form and siting
· expansion needs
· choice of materials for foundations/sub-structure; super-structure; enclosure and cladding methods; and appropriate internal finishes and
· choice of structural techniques, including economy and ease of construction
Final master plan
The last step of this design stage will be to prepare a final master plan drawn accurately to scale and incorporating all the factors evolved during the process of design and consultation. I he master plan forms the framework for the development programme, integrating the final building designs with the vehicular and pedestrian circulation systems. A typical example of a final master plan, illustrating all the essential components that should be included, is shown in Figure 10.
Detailed site planning and infrastructure design
Detailed site planning proposals and site infrastructure layouts can be finalised when a final master plan has been agreed. In preparing proposals for a comprehensive site development the following types of infrastructure (which are discussed in greater detail in Chapter 14) would typically be included:
· site preparation, which would comprise stripping of the top soil and then cutting and filling the site to obtain level platforms for buildings and even grades for roads. Frequently the levels of sites have to be built up and this requires compacted fill to be laid on a geotextile blanket. Where soil conditions arc extremely damp, horizontal and vertical sub-soil drainage may be required. Soil conservation measures, sediment control devices and earth or concrete retaining structures may also be needed. These works should ideally be undertaken as a separate preparatory contract. This will allow the fill areas to thoroughly settle before work starts on the main infrastructure and buildings;
· the road and footpath system will be the main component of the site infrastructure, constructed as either a concrete pavement or a flexible bituminous pavement. Roads should be provided with kerbs and integral gutters. Paved off-site connections to existing main roads, including improvements to junctions, may also be required;
· car and lorry parking facilities will be needed, designed to accommodate peak-hour traffic flows, and using a similar type of construction;
· a surface water drainage system will be needed, designed to cope with storm-water flows, possibly with some on-site storage for peak discharge conditions. Drains will be a very important infrastructure component in the tropics. Except in very low rainfall areas, storm water is usually carried in open channels, which are either covered with steel grating or concrete slabs. Because of the large amount of impervious roof and road surfaces in markets it is also likely that any existing site outlet to a natural drainage course will need to be improved;
- water mains connection will be required, either from an existing public supply or from a bore hole. To provide adequate on-site storage, the supply should feed either an underground water reservoir or a main overhead service tank, or a combination of both. The main tanks would service a reticulation network, supplying overhead tanks in individual buildings and a system of fire hydrants;
· a piped sewerage system is needed, going either to septic tanks, with partially treated effluent going to surface water drains, or preferably directly to a main sewer, if this is available and economically viable;
· an electrical supply will be required to the site (usually an 11 kV overhead line) going to a transformer unit and main switch room. This will serve an earthed distribution lighting and power network, preferably located underground and a street/site lighting system; and
· a main telephone system which is an increasingly important component of market infrastructure. As well as providing facilities for sellers and buyers to arrange deliveries directly by telephone it can also form a major element of a market price information system, using facsimile machines and computer modems.
Additional survey requirements
At the end of the detailed design stage the need for further surveys may have been identified (see Chapter 11). These might include additional socio-economic surveys as part of the project feasibility studies (see Chapter 5), including repeating previous surveys for different seasons.
Further topographic, material suitability and geo-technical engineering surveys may also be required for project implementation purposes (see Chapter 6).
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