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Kenya Engineer
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The labour-based method for road construction

By Asfaw Kidanu
View other stories from Kenya


Editorial

Background to problems with the road network in Kenya Like many Sub-Saharan African countries, Kenya finds it increasingly difficult to sustain heavy equipment-based construction and maintenance of its roads. This is largely due to the slow pace of the economy, low foreign currency earnings, and the prohibitive rise in the price of equipment (in most of African countries the foreign component of equipment-based road construction is between 60 - 70% of the total cost). Because of this, the country cannot expand or maintain its road network to support the economic activities in the rural areas where the bulk of the population live. Slower economic performance coupled with rapid population growth has also meant falling real wages for unskilled labour and acute unemployment.

How can a country deal with such problems?
Countries with these problems need to be innovative, using technically and economically feasible techniques of road construction and maintenance. These include reorientation of public sector expenditure toward the use of more labour-based techniques, which make use of the abundant labour force and appropriate technologies.
Policy makers and planners need to look at cheaper and local-resource-based alternative approaches to road construction and maintenance. The labour-based approach is a positive alternative.

What is the labour-based method?
The labour-based method is a mode of construction which optimises the employment of labour and makes use of light equipment only when required. These can be used as a substitute for heavy construction equipment, for many road making activities. Activities such as excavation, loading and off loading, forming of road, masonry and concrete work, can be effectively executed using labour equipped with the correct hand tools. Equipment is only required for activities such as hauling (more than 200 m) and compaction, on which the use of labour is uneconomical and inefficient.

How does the labour based-based approach work in practice? Over the last two decades the labour-based technique has been employed in many countries and experience shows that, provided it is well organised and managed, it is generally cheaper and produces a well-engineered road with a speed and quality comparable to that of the conventional machine-based method.

Benefits in using labour-based methods
There are many benefits. They include: a significantly lower foreign exchange requirement, development of local management skills (for construction and maintenance works), utilisation of abundant local labour resources, productive employment generation in rural areas, a significant portion (more than 50%) of the direct costs being injected directly into the local community, development of the local light industry (supplies of local equipments, tools and materials, and repair services), reduced environmental damage during construction, and ensured sustainability and self-reliance.

Disadvantages attached to the use of labour-based technique
As with all techniques there are some disadvantages. The labour-based technique cannot be used for all types of roads; it is management intensive (requires a great deal of supervision), and it is susceptible to labour problems.

In this respect it is very important to note that the choice of technology (machine- or labour-based, or the combination) has to be based on the evaluation and careful consideration of the economic, social and political benefits of all the possible alternatives. Labour-based technique, although it can be used to address various social problems (unemployment, health care, etc.), is basically an engineering work. Thus, the technical feasibility of substituting labour for capital must ultimately be dictated by the engineering requirements.

Application of the labour-based approach

Like any other engineering works, labour-based technique may work in certain conditions and may not be economically and/or technically feasible in others. The road engineers must identify variations in local conditions, determine the type of work required, and choose an appropriate technology.

The following are some of the indicators

in determining suitability of labour-based methods: • population density - it is generally desirable to have a minimum of 25 persons per square kilometre within reasonable travelling distance of the construction or maintenance site.
• terrain condition - excessive earth works, rocky outcrops and steep vertical gradients (higher than 12%) can make labour-based methods comparatively uneconomical.
• traffic - highly trafficked roads (more than 100 vehicles per day) would generally require a higher standard of geometric alignment resulting in a lot of cut and fill.

• availability and proximity of suitable road construction materials, eg gravel, water, etc.

• availability of local skills, ie technical and managerial - these are essential in achieving efficient labour-based work organisation and must be available from the outset.

• adopted standards - appropriate level of access and corresponding geometric design standards have to be agreed upon before deciding the technology to be used.

• future maintenance strategy (labour- or machine based) - this may affect the outcome of the rehabilitation exercise, eg shape of drainage, leaving provision (trained labourers, gravel stockpiles etc.) etc.

Misconceptions about labour-based techniques

The following are some of the misconceptions commonly expressed by some engineers:

1) Labour-based work is sub-standard
Labour-based methods do not result in sub-standard work. Experience in several countries (including Kenya) shows that there is little or no difference between the quality of roads, in a similar category, produced by labour-based methods and those built using machine-based techniques.

People get the idea that labour-based work is sub-standard mainly from lack of hands-on experience on labour-based road works but also from unbalanced comparison between roads of varied classes. For instance, it is very common to find comparisons being made between the qualities of rural feeder roads (eg 0/6 category in Kenya) built by the labour-based methods to that of secondary roads (gravel) built using machines. The quality standard of a given road directly relates to the function and other conditions of the road, which are reflected in its classification. Comparisons should only be made between roads in a similar category otherwise the whole exercise is erroneous and misleading.

In fact there is no separate design standard for roads built by the labour-based method, as standards depend on the classes of road and not on the mode of construction. Hence the labour-based method must achieve the same standard of a finished road, in terms of, eg compaction, shape of a carriageway, riding quality etc as that of machines.

The quality of work on the labour-based works is achieved by the use of proper mix of labour and relatively simple mechanical equipment such as tractor and tractor-drawn implements. Proper set-up and management of works is also crucial for the quality of a finished road.

The use of tractor-based technology for hauling, grading and compaction has allowed standards to be more comparable with equipment-intensive road works. Substantial evidence exists which indicates higher availability and utilisation rates for tractor-based equipment, in comparison with alternative heavy equipment, in many developing countries.

2) Speed of construction
Labour-based methods can achieve speed or productivity comparable to that of machine-based methods. Speed of production in labour-based works is a function of the strength of organisation, management capability and availability of resources. Provided these conditions are met, labour-based work moves very fast. Note also that labour-based works are less prone to interruptions due to break downs to key equipment, lack of spares etc.

A typical labour-based unit in Kenya employs 200 labourers and 3-4 tractor and trailer combinations, and has a capacity of producing 4-5 km of completed gravel road per month. However, there is no theoretical limit to the number of units deployed in any roadwork as long as the required labour and equipment are available.

3) Problems with labour management
It has been suggested by some engineers that one grader is only one problem but one hundred labourers are potentially one hundred problems. Interestingly experiences in many countries (Kenya being one of them) have proved that workers cause the least of the problems, provided they are fairly treated and paid on time. Without exception it is the few items of equipment needed for the labour units that are the main restraint to progress.

Nonetheless, it is recognised that there are many potential difficulties associated with a labour-based technology and they need to be addressed accordingly. Firstly, large number of engineers and technical staff must be trained in the necessary technical and administrative skills. Secondly, the necessary funds have to be mobilised to ensure the work force is promptly paid for work done. Thirdly, a proper system of monitoring and supervision has to be put in place.

Labour related problems
To avoid labour related problems particular attention has to be given to:
• recruitment of casual labourers - a totally transparent and fair recruitment procedure needs to be developed.
• conditions of employment for casual labourers - there should be a direct relationship between wages paid and output achieved.
• definition of tasks - each individual labourer should know exactly what is required of him each day.
• provision of high quality tools - it is important to note that it is a management responsibility to help make the work easier for labourers. Hence, supply of good quality hand tools must be ensured.
• prompt and accurate payment of staff and labour - no work should be set until the necessary funds are already in place.
• planning, reporting and monitoring procedures - effective management decisions require accurate information to be available on time.
• research and development - like any other technology, labour-based methods have to be constantly reviewed and improved based on the experiences gained on site and latest engineering knowledge.

Conclusion
It must be acknowledged that labour-based technology is still a relatively new concept for many engineers, even though it predates the modern road engineering concept. It needs to be developed further in order to realise its full benefits and potential. The role of today’s engineer, therefore, should be to improve the labour-based technology by applying sound engineering and management judgement, and the latest knowledge and experience, whilst still aiming to satisfy the economic and developmental objectives.

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