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Regional Seminar Proceedings 1993 Handtools and Equipment - The Current Scene By Collins Makoriwa, ILO National Professional, ASIST, Kenya SYNOPSIS This paper looks into the current state of affairs of hand tools and equipment employed in labour-based projects in sub-Saharan Africa. Special emphasis is given to the equipment used in Kenya, Botswana and Lesotho. Possible steps are suggested to improve current problems. These solutions are general and may not apply to all places. Hand tools Preamble Through the rest of this paper, the term tools will be used to refer to hand tools whilst the term equipment will refer to machinery and its peripheral attachments. Hand tools are the crux of the issue in labour-based roadworks. They are the main items used by labour in the construction and maintenance of roads. It is possible to construct labour-based roads using labour and tools only, but it is not possible to construct these roads using labour and equipment without the use of tools. General In spite of hand tools being so crucial to labour-based road construction they have not been given the attention they deserve. Generally, the labour-based road construction industry is agreed upon the types of hand tools to be used for various operations. What is generally lacking is an appropriate quality standard for the hand tools employed and a specification of the dimensions ofthe various hand tools. Several institutions have drawn up standards for hand tools (BSI, ILO etc.). These standards are generally not met by projects due to several reasons. The main ones are: Lack of awareness of the impact of good tools on the labourers’ output Incompetent purchasing officers Good tools are not available Legislation restricting importation of quality tools. Lack of awareness of the impact of good tools on the labourers’ output This is actually the main reason why the tools used today in many projects are in the state they are in-despicable. This lack of awareness of the impact of good quality hand tools spreads from the project managers to the labourer using the tools. The level of awareness if obviously different. Of course this is not to say that project managers and other senior practitioners are unaware that the quality of the tools have an impact on the productivity of the labourer. What many of these people often are oblivious to is the impact of good quality tools on both the project costs and output. The following example will illustrate the minimal effect an increase of tools prices contributes to the project costs.
If spade type B is alleged to increase the productivity of the labourer, then by how much does the productivity have to increase to justify the purchase of spade type B?
Thus the excess costs incurred due to use of spade type B is 155.60 Kshs. The use of spade type B can be justified if during the four months it is employed it can save 156.60 Kshs. Where would this saving be made? Now 155.60 Kshs is about two days labourer wages. Thus if the user of the tool is able to finish the task that would take him 80 days then the purchase o spade B is justified. In this example a 100% increase in the price of a spade can be justified if it results in a 2.5% increase in productivity. A mere increase in the task rate from 3m3 /day to 3.075m3/day! It is this sort of impact of the quality of hand tools on the productivity that needs to be imprinted in the minds of the policy makers in the labour-based road construction business. In the above example even if the increase in cost results in an increase of productivity that just breaks even, there are non-quantifiable benefits to be attained. These would typically be less fatigue, less wear on the user’s hands, increased motivation for the labourer etc. If the spades actually lasted longer (as would be the case in reality), additional benefits would include less hassle of tools procurement and replacement. After following this computation we are forced to conclude that the typical excuse of having no money to purchase good quality tools does not hold water. What about the lower level of people engaged in this labour-based road construction business? These people usually have to contend with what they have in available. This is not to say that they have no role to play. In fact theirs is as important as the decision to buy appropriate tools. Field workers need to be taught the benefit of keeping their tools in good condition. The productivity of the tool increases by as much as a factor of two when the tool is actually kept in good shape. Thus pangas, hoes, pickaxes etc. have to be sharpened and kept sharp. It is thus in the interest of all parties to ensure that the hand tools are kept in good shape. A system needs to be set up on every site to ensure that tools are maintained in order. It is also important to train the labourer on what the attributes of good hand tools are. Incompetent purchasing officers Often, the actual purchase of equipment is done by administrators who have no technical knowledge about either the tools themselves or the job they are to be used for (e.g. government tender boards etc). As a result, their decision is often based solely on the price. Good tools are not available This is a tricky situation although all may not be lost. It is important to realise that most of the tools are manufactured are intended for use in the agricultural industry (with the exception of mattocks and pickaxes). They are thus of sufficiently good quality for this purpose. In such a case the first thing to do is to identify a local firm with the capacity to produce good quality hand tools. Usually if the batch of hand tools to be procured is substantial, the firm will be willing to adjust the standards of the hand tools. In Southern Africa, where there is a big mining industry, which demands and provides an effective market for good quality hand tools, there is a big difference in the quality of the hand tools available on the market. Nonetheless, if arrangements are made to purchase a bulk order from a single manufacturer, it is often possible to ensure that the hand tools supplied will be of sufficiently good quality. Thus the market as a whole cannot adjust its standards for the road construction industry but a single manufacturer can usually meet the standards. Alternatively, one can draw up a tender document with explicit quality requirements that will result in the tendering firms actually increasing the quality of the hand tools. Legislation restricting importation of quality tools When all attempts to obtain locally manufactured hand tools of appropriate quality have failed then one has to turn to the foreign market. The main problem is usually government legislation restricting the importation of such items. Technical issues A good hand tool basically is a tool that will aid the person performing the specified task to achieve the task with the least possible effort and with a minimal cost to the project. What are the attributes of a good tool? The user will not have to expend unnecessary effort due to a poor posture, poor grip etc. It is also imperative that a good tool lasts a reasonable length of time if it is to meet the second criterion. Although the time the tool lasts has been shown to have a relatively small impact on this issue. Several studies have been conducted into the performance of hand tools and they all clearly show that the prime object to be met by good quality hand tools is that they should increase the productivity of the labour. This is because hand tools contribute a minimal portion to the cost of labour-based road construction. Handles The various aspects of the handles of hand tools that need to be taken into consideration when purchasing are: the shape (variation of X-section along length), finish and length. The main function of a handle is to enable the user of the tool to apply the tool head to the job in hand. The shape of the handle thus has to facilitate this procedure. The sketches below show appropriate hand tool handles. These dimensions should not be taken as absolute but rather as guidelines highlighting the good aspects of handles.
The finish of the handle saves excessive wear on the user’s hands. A good tool handle should be sanded and preferably varnished. The wood thus has to be of a type that does not splinter. The handle should be sufficiently long to result in an ergonomic posture of the user. For spades and shovels, the best handles seen are the type made of iron which can either be welded onto the head of the tool or cast out of one piece. A common problem is the weakening of various elements of the spade. Thus the heads and handles of spades if riveted to the handle tend to loosen with use. Tool heads Spades also have to be sharpened on the outer edge of the blade prior to use. If the spade is then used on sandy soils (highly abrasive) the spade will remain sharp throughout. Hoes, mattocks and pickaxes also have to be sharpened. Here one has to be careful about the angle the blade of the implement is sharpened to. If the blades/points of these implements are sharpened to a small angle the result is a rather weak edge. It is also important when purchasing these tools to ensure that the eye of the tool is oval and tapered. This ensures that a reasonably tight bond can be achieved between the handle and the head. Equipment Preamble The use of various equipment in labour-based road construction programmes has a long history-plagued with problems! The technology is an intermediate between heavy construction and standard agricultural equipment. This cat is what causes the procurement problems for labour-based practitioners. There are few standard designs that adequate fro the industry. Today, standard agricultural tractors are employed for hauling and modified agricultural trailers or trailers based on agricultural designs are widely employed by the industry. The type of equipment employed varies from project to project but basically these are the equipment types employed in most labour-based project. tractors, General In an attempt to solve various problems associated with equipment use in labour-based works, various things have been tried. The current trend is to pass more of the responsibility to the private sector by: hiring of plant and equipment from the private sector, giving out the maintenance task to private workshop or using contractors to do the jobs that require equipment. The hiring of equipment from the private sector tends to result in more efficient use of the equipment in question. Among the equipment that could be hired from the private sector are lories and rollers. There are other types of equipment that may be difficult to hire from the private sector e.g. towed graders. This is because such equipment is not commonly used in other industries and thus is not widespread. For one to be able to hire equipment at a reasonable price there must be sufficient supply of the piece in question. Thus if there is only one grader in a country, the hire cost for that grader may be more than the computed price of owing one. There also must not be a competing industry offering high prices for the equipment. This has been a problem in Kenya with the labour. During harvesting time, the farms pay relatively better than labour-based works and thus all the road workers "disappear" into the farms. An intermediate between fully renting equipment is to own equipment but to have it serviced by outside workshops. The principle advantages of this arrangement are: less down time no need to stock a huge bastion of spares parts which may never be used Irrespective of the policy adopted when purchasing or receiving equipment grants, one has to avoid any odd makes of equipment. Thus it is no use buying a very robust reputable make of tractor if you will be the only user of that make in the country. In fact the most important thing when purchasing equipment apart from the operating costs is the availability of spares. If a project has equipment it is imperative that a regular servicing schedule is drawn up for each piece of equipment. Technical issues Tractors Tractors are employed in labour-based works mainly to haul various implements. The main uses are to haul trailers, bowsers and towed graders. A problem is that the standard agricultural tractor is not designed for rigorous haulage purposes and thus run out of life after only five years use in the labour-based road construction business. On the other hand the same tractors last about seven to ten years when employed in other industries. The right piece of equipment to use tor these jobs should be haulers specifically designed for the job. Whey then are tractors used instead of haulers? The main reason is that haulers cost much more than tractors. With an average cost factor of two times the cost of an average tractor, many project managers find it difficult to justify the cost of the hauler. The other feasible option is to use lorries instead of the tractor-trailer combination. Here the other disadvantage is that the truck is not a very versatile implement. A truck cannot be efficiently used to haul other paraphernalia that are useful in labour-based road construction sites. Thus while the tractor may be used to tow trailers, bowsers, towed graders, rollers etc, the lorry cannot be effectively used except for bed haulage. The cost of trucks also does not compre favourably with the cost of tractors. The other disadvantages of the other system is that lorries are also not very robust animals. They require more care than tractors and are susceptible to damage due to poor handling because for several peripheral devices. Trailers Trailers are in use in several labour-based projects. They are used to haul gravel and for camp support activities. They have been in use in labour-based road construction programmes for about 20 years. Ironically several designs are still being tried out with a very high failure rate. The road construction industry is faced with a problem because standard agricultural trailers are too weak to be used for labour-based roadworks. On the other hand, standard trailers, robust enough for labour-based works are way overboard for small labour-based projects. Thus several projects have to arrive at a suitable design and have it trailer-made for the project. Most projects use trailers of size 3m3 to 4m3. This size is appropriate if the haulage distances are small—typically less than 4 km. As the haulage distances increase, either the volume of the trailer has to be increased or the haulage speed increased to keep the exercise economical. Here is where usage of trucks becomes more economical. Recall that 3.5m3 of soil weighs about 5.2 tonnes. Small trucks have typical capacities of seven tonnes. A standard agricultural tractor has a maximum speed of slightly over 20 km/h. A typical seven tonne truck will comfortably do 40 to 60 km/h on country roads, speeds unattainable by a tractor even when unhitched. There are thus two options for projects faced with long haulage distances: use lorries for haulage of gravel or use tractors with either increased speed and or larger trailers attached. If the project manager decides to implement the first option, he will immediately solve all haulage problems. On the other hand he looses the dexterity of the tractor. Usually he will also have to contend with higher maintenance costs. The second option is a bit tricky because even the "fast" tractor/hauler will usually do a maximum speed of only about 30 km/h. In fact with tractors, the limiting factor when it comes to speed in the driver’s comfort. In fact experiments have been conducted in this field in Kenya on gravel roads and it was observed that above 18 km/h the drivers have to stand up because the ride becomes too rough. "On slopes from 0-5% pulling an empty trailer, the speed is limited by the driver’s ability to stay in the seat. This speed limit depends on the condition of the road surface. On the test roads, fairly smooth RAR’s or MR’s this speed was 16-18 km/h."1 1
A more rational approach to the issue would be to employ trailers of larger capacity—say 6m3. The problem is a monstrosity of such dimensions would weigh about 12.8 tonnes. Two tonnes for the unladen trailer and 10.8 tonnes for the payload. This type of trailer cannot be towed by the standard 65 hp hauler, and a larger hauler of capacity › 110 hp is required to haul this load. If this tractor/hauler is to be used to haul gravel only, then the investment will be difficult to justify. On the other hand if the hauler/tractor is to be used for other operations, especially gravelling in heavy laterite soils, then purchase of the hauler can be justified. Also to be considered is the available turning space for the tractor/trailer combination. Hence for projects situated in hilly terrain there may not be sufficient turning space for a tractor/trailer. Trucks Trucks are not commonly employed for haulage of gravel in labour-based projects except in Lesotho where they are extensively used. This may be due to the very hilly terrain (no turning space). Small rucks of seven tonne capacity are definitely more productive and economical than the tractor/trailer combination especially for long distance haulage (> 5 km). The only disadvantage of employing trucks is that the truck cannot be used for other purposes such as towing a grader etc. Roller The type of roller used in labour-based works is generally a huge dead-weight roller of between two and five tonnes. Self propelled vibrating hand rollers are widely used in Ghana and Lesotho. In several countries no compaction is done on the gravel deposited on the carriageway. Dead weight rollers produce results that are comparable to vibrating roller if a sufficient number of passes is made. It is important to ensure that the size of the roller specified when purchasing is proportional to the rate of work output. Nevertheless experience has shown that very small roller are usually not able to run for sustained periods of time. An example is the Bomag range of rollers. These rollers are excellent but on labour-based road construction sites, only the Bomag 90S has proved robust enough to survive the tasks it is applied to. Hitches There are basically three types of hitches available: ball and socket joint, The ball and socket joint is the most robust of the three types of eyes. It needs to be regularly checked to ensure the cup bushes in the socket are not worn out. It is also the most expensive (US$ 1000 in Europe). It cannot be fabricated in a small workshop. A ball and socket arrangement is usually needed for heavy towed equipment e.g. towed graders. The pin and eye arrangement is simpler than the ball and socket joint and the various components can be fabricated in a relatively simple workshop. This type of hitching arrangement allows the pin to wobble in the eye, otherwise when the trailer applied a torque on the tow bar, detrimental stresses would be induced in the whole hitching apparatus. The various elements in the hitch could be fabricated such that either the towing eye fails under stress (end bearing failure) or the towing pin fails. It is safer to choose the former because if the pin shears, the failure is usually abrupt unlike end bearing failure which occurs slowly with time. Some attempts have been made at fabricating towing eye units with a bush in the eye. The idea is to restrict the wear and tear to the bush only so that only the bush will have to be replaced. The problem is that for an unbraked trailer, the towing pin is constantly hammering against the towing eye and this constant jarring knocks out the bush in about two weeks of use. In Kenya the solution has been to simply cut the towing eye unit out of a steel plate 1" thick. This is then welded as it fails under end bearing stress, and after a few times of welding, the whole unit is replaced. The eye and hook hitch is basically like the pin and eye except that the pin has been substituted for a hook. There are no advantages of having a hook instead of a pin especially if the hitching apparatus has a mechanism to prevent the tow bar from accidentally unhitching from the top of the pin or hook. In fact the problem with using a hook instead of a pin arrangement is that the hook cannot be fabricated in the workshop, whilst for the pin even a standard old king pin from a lorry or tractor can be used for the pin. Anyway whatever the towing arrangement one goes for it is important to ensure that all towed apparatus is compatible with the tractor hitch. References
II. Handtools and Equipment for Labour-based Construction: Lesotho’s Experience By Athie T. Lehobo, ILO Civil Engineer, Maseru, Lesoth This paper provides information on hand tools and equipment which the Labour Construction Unit (LCU) in Lesotho has used to implement construction projects by labour-based methods. It reviews research and development work undertaken by the LCU regarding compaction equipment, use of ox-carts and donkey panniers, cost comparison of haulage by tipper and haulage by tractor and trailer, improvement of existing hand tools and efforts to secure local manufacture of good quality hand tools suitable for labour-based technology. Introduction Efficiency of labour-based construction technology depends heavily on the use of suitable heaby duty hand tools and simple items of equipment. The tools should be suitable in shape, size, weight and balance, strength and sharpness and of good construction. Therefore it is very important for those countries which apply the technology to improve the design of their existing hand tools in order to raise productivity and enhance efficiency of the technology. Local manufacture of tools is very desirable in order to sustain continued improvement. This paper examines the status of hand tools and equipment used in Lesotho to carry out labour-based construction projects. Hand tools available in Lesotho The hand tools available in Lesotho are all imported from the Republic of South Africa (RSA). The Labour Construction Unit (LCU), which is the Government department charged with responsibility to implement labour-based methods, buys hand tools from the local suppliers who import them from the RSA. The LCU labourers are very familiar with these tools from their previous employment in the mining and construction industries in the RSA. They are very skilful in their use. However, they are resistant to the use of new and strange tools such as the mattock. Excavation only So far, the pickaxe and crowbar are the only hand tools used for excavation work. They are very suitable for the dense non-cohesive ans stiff and stony cohesive soils found in Lesotho. The handle for the pickaxe is made from hardwood and its head weighs about 3 kg. The crowbar comes in small, medium and large sizes and measures between 1.5 m and 1.8 m long. One end is chiselled while the other end is either wedged or hammered. The weight varies between 7 kg and 11 kg. Excavation and loading the shovel has so far been the only tool used in Lesotho for heavy excavation of soft cohesive and loose granular material. It is an excellent loading tool for all materials except wet clay which sticks to the tool. There are two types: round and square nose shovel. The latter and the spade are seldomly used on the LCU construction sites. Long-handled shovels are rare and they are used only for desilting culverts. Spreading The shovel and heavy duty rake are used for spreading out fill material and gravel. The handle of the rake or spreader is made from metal tubing and its head is made from thick flat iron. The rake has about 16 prongs and each is about 75-100 mm long. Compaction Steel hand rammers are used for small compaction work. For large compaction work, the vibrating pedestrian-operated roller, Bomag BW-90s, is used. Compaction of restricted areas, such as beddings for culvert pipes where the BW-90s cannot be used, is done by a hand-operated compacting plate. There is no animal-drawn compaction equipment in Lesotho. Haulage The wheelbarrow is extensively used for hauling distances not exceeding 200 m. There are two types in Lesotho: an ordinary household wheelbarrow which has a shallow and wider tray, and the construction wheelbarrow with and narrower tray. In 1988 the LCU introduced the third type, of Swedish origin. For hauling distances over 200 m, the LCU uses a combination of tractor and trailer and tipping trucks; the latter being more economical and extensively used. There are no animal-drawn carts for haulage of construction materials even though there are many ox-carts used by farmers for agricultural purposes in the country. Rock drilling and breaking Tools for rock breaking are steel chisels in various sizes, stone (4 lb) hammer, crow bar, sledgehammer, and feathers and wedges. A skilful labourer can easily produce between 0.35 m3 and 0.5 m3 of broken sandstone by using a stone hammer and chisels. The sledgehammer alone is a good tool fro breaking small stones and boulders. The crowbar is driven by hand into cracked rocks or boulders and then used as a lever to split the rock. Feathers and wedges are placed inside a line of holes drilled into a rock or boulder, and the wedges are sledgehammered in succession to split the rock or boulder. Light equipment for rock drilling and breaking range from hilti drills, pionjahr and pacebrakers for small quantities of work. For large quantities up to 2,000 m3 of rock breaking, a 175 cfm or 250 cfm compressor is recommended. Similarly blasting is recommended as the most economical method or breaking rock when quantities are more than 2,000 3. Review of research and development work With regard to hand tools and equipment suitable for labour-based technology, the LCU undertook the following research and development work: use of dead weight concrete roller use of ox-carts and donkey panniers cost comparison of haulage by tipper and haulage by tractor and trailer improvement of existing hand tools local manufacture of hand tools. Dead weight concrete roller The first concrete roller was made on site and used to compact the runway of Seshote Air strip in December 1977. It had a cylindrical shape of 45 cm diameter and 90 cm height. It was designed to be pulled by labourers. Gravel was watered to bring the moisture content to an optimum. Compaction was done in layers of 75 mm. The compaction results on the final 15 cm layer were satisfactory after a reasonable number of passes. The gravel was of fine material. The concrete roller was then used on a number of airstrips during 1978 but its use was later discontinued for the following reasons:
Ox-carts and donkey panniers The LCU was keen on testing the viability of ox-carts and donkey panniers for haulage of fill and gravel for its labour-based construction projects. In 1986 the LCU bought donkey panniers for use on the construction of the access road to Tebellong Hospital in Qacha’s Nek District. There were many donkeys in the area owned by the villagers who were very interested in the project. The LCU had expected good cooperation from them to hire their donkeys for provision of gravel. It was a big surprise to the LCU when the villagers refused to hire their donkeys to haul gravel using panniers. Then the use of donkey panniers was abandoned. In the same year, the LCU bought a number of ox-carts for use on the regravelling of Mazenod-Mokema Road which traverses a highly active agricultural area. The farmers who owned cattle were approached to negotiate commercial hire by the LCU. The farmers refused to hire their animals. They said that animals were for agricultural purposes only. Very disappointed, the LCU continued with its decision to test the viability of ox-carts for haulage of gravel. Two oxen were bought and brought to the Training Site at Ha Thetsane. The two animals were then used to provide gravel for the Training Site. Unfortunately, recorded productivity data for haulage by ox-cart unsatisfactory. However, observations made during the test period indicated that the ox-cart was not a viable method of hauling gravel in Lesotho where terrain is very rugged with steep gradients. It was observed that the animals had difficulty in pulling a loaded cart uphill and to restrain the cart while going downhill. The trailers were of two types: tipping, and flatbed trailers had two axles, and though required extra person days to unload, were more easily manoeuvrable than the tipping trailers which had one axle. At the end of the project the LCU compared recorded data for haulage distance and type if terrain as follows: No. of tractordays (trd) per km = 61 No. of 6 m3 tipper days (tpd) per km = 30 Hire rate for combination of tractor and trailer per hour at 1985 prices = M28.00 Hire rate for tipper per hour at 1985 prices = M24.00 No. of working hours per day = 9 hours Cost comparison per km Tipper & Trailer cost = 61 trd x M20/hr x 9hrs/day = M15,372 Therefore, the cost of a combination of tractor and trailer was found to be more than double the tipper cost under same conditions. Improvement of existing hand tools, Tuesday /12/93 During December 1987 and January 1988 the LCU commissioned a Tool Specialist to assess the situation of hand tools used by the Unit. In his report the Tool Specialist indicated that good quality tools available in Lesotho wee pickaxes, crowbars and sledgehammers and the poor range of tools were shovels, rakes and wheelbarrows. According to his terms of reference, the Tool Specialist was to produce designs and prototypes of good quality tools to replace those identified as poor and unsuitable for heavy manual work. He made the prototypes of a wheelbarrow, heavy duty rake, hand rammer, filling tray and yoke. The two most welcomed prototypes were the wheelbarrow and heavy duty rake. The heavy duty rake was a good quality tool. It was very different from, and much superior to, the existing range of rakes which were only good as garden tools. Its prongs were made from thick steel plate and the handle was made from metal tubing. This was unquestionably the right tool fro heavy manual work on the construction site. The wheelbarrow prototype appeared to be an ideal wheelbarrow, one which carried a big load, was easy to balance, push and tip, and lasted longer. However it was desirable to field test the prototypes before large scale production. In the field the performance of the new wheelbarrow was compared with that of the existing construction wheelbarrow imported from the RSA. The following observed during the field tests: Area of Comparison Existing Wheelbarrow New Wheelbarrow Capacity Positon of load with respect to the wheel Wastage Manoeuvrability Ability to push Ability to tip Stability Capable of holding 65-70 litres Load between the wheel and the legs so that some of the load was carried b the pusher Very little wastage of contents due to narrow and deep tray or bucket Easy to manoeuvre because of good shape and size or bucket Easy to push with the pusher carrying part of the load Tipped easily with its bumper acting as fulcrum Would stand unsupported on a sloping ground while carrying full load Capable of holding over 70 litres Load almost over the wheel and nearly all the load carried by the wheel Contents easily spilled because of wide and shallow tray or bucket Not easy to manoeuvre because of the wide and shallow tray with a rectangular shape Easier to push with almost all the load carried by the wheel Difficult to tip, had no bumper Needed support when loaded and standing on a sloping ground, otherwise started to move by itself Local manufacture of hand tools As part of his terms of reference the Tool Specialist assessed the potentiality of existing workshops in Maseru to manufacture the prototypes. He visited the workshops and talked to the owners who were invited to a half-day demonstration of the prototypes. In his report, he stated that manufacture of hand tools for which prototypes had been made was quite feasible in Maseru. He provided the LCU with a list of interested manufacturers who were later contacted to be issued with a government order to commence manufacture of hand rammers, heavy duty and wheelbarrows. Eventually only one manufacturer was able to produce wheelbarrows and heavy duty rakes. Production of these implements was good until the 1991 riots in Lesotho. The manufacturer’s premises were damaged. Since then the production of wheelbarrows has been very limited and nothing for heavy duty rakes. Conclusions and recommendations
III. LCU’s Experience with Compaction Equipment and its Crushing Effect
Background The Labour Construction Unit (LCU) is constructing/upgrading roads in the rural areas of Lesotho. Annually the LCU constructs more than 60 km of rural roads all over the country. The roads upgraded by the LCU have the following specifications: Class B and below surface type gravel carriageway width 6 m Before construction, some roads had an Average Daily Traffic (ADT) as high as 45 vpd, mainly small passenger buses and pickups. Traffic counts made after construction has showed a 25% increase. This makes it essential that some sort of compaction is required at least to take the initial traffic load. Compaction in the LCU At each construction, site, compaction is applied at three stages, i.e. excavation to level, camber formation, and gravelling. At each stage the compaction length is about 100 m. As the compaction length and thickness are small, heavier equipment are not recommended. Hence the LCU has been using pedestrian vibrating rollers for the past fifteen years. Good results are achieved using the Bomag BW-90's. See Appendix 1 for the specification. From LCU’s experience the aforementioned rollers have the following advantages: relatively easy to operate—only on day’s training is enough easy to maintain do not require big and sophisticated equipment to transport—ould be loaded on a small trailer and towed by a 4 x 4 pickup parts are easily available locally comparatively less costly. If the basic preventive maintenance is conducted regularly, these rollers could work at relatively high performance for longer periods without major breakdowns. The major causes of breakdowns on these rollers are the following: changing gears (forward reverse) without stopping driving the rollers for longer distances, i.e. transporting from one place to another continuous running of the engine for longer periods. Compaction is done in layers of 150 mm at each stage i.e. excavation to level, camber formation, and gravelling. Water bowsers of 1000 litres capacity are used for watering the compaction area. Test samples taken from the field have showed more than 90% compaction. Usually these results are achieved after 7 to 10 passes. Gravelling All roads constructed by the LCU have a gravel surface. Before starting quarry excavation test samples are collected and sieve analysis conducted to determine the suitability of the gravel. After excavation, the gravel is loaded on trucks without ant sieving. Bigger sizes of stones will be identified visually and removed at the quarry before loading and at the site while spreading. In cases where quarries with well-graded gravel are not available in the area, we are obliged to use what is available. This results in using larger size aggregates. This will gave the following effects: corrugations will be formed straight after construction less riding comfort within a very short time requires grading or filling a few weeks after completion. Such roads will have high maintenance cost as they require light grading more often than usual or requires spreading of a layer of materials on the surface. Usually regravelling is planned at a seven year cycle in the LCU. This regravelling cycle will not be met if bigger size stones are to be used. Bigger size stones are crushed in two ways: using a mason’s hammer for bigger sizes crushing using rollers while compacting. The LCU is undertaking field tests to find the crushing effect of the Bomag BW-90. Two gravel samples are collected, i.e. one dumped gravel before spreading, and a second sample after the gravel is spread and compacted. Then sieve analysis of both samples will be conducted to establish the crushing effect of the rollers during compaction. Although the crushing effect depends among other factors on hardness of the rock and number of passes, initial results have been satisfactory. Appendix 1: Manufacturer’s Specification of the BOMAG BW-90S
IV. Equipment Maintenance By Jim Hamper, CIDA Mechanical Engineer, Introduction The purpose of this paper is to present some ideas for discussion on the maintenance and procurement of suitable tractor based equipment used in road maintenance. As the geographical and economic conditions vary from country to country, it cannot be stated categorically that one piece or design of equipment that works well in one area will necessarily be successful in another. Recognizing this, it should be noted that the view expressed in this paper are the results of the experience gained through the Rural Access and Minor Roads Programmes in Kenya. Equipment maintenance The maintenance of equipment is an important and integral component of the road maintenance sector. For the reader to have a proper perspective on the topics of this paper, only the following types of light duty equipment will be considered: Agricultural Tractors 45 - 60 hp. 2 WD. Land-Rovers As service vehicles Trailers 3 m3 Non tipping Trailers 3 m3 Tipping as an option Lorries 7 tonne flat bed Motorcycles 125 - 175 cc It is assumed that all equipment is owned by the ministry and all repairs and maintenance is done in-house as opposed to farming out to dealers and/or local repair shops. In the beginning of the Rural Access and Minor Roads Programmes in Kenya the idea was to have a self-contained roads into so that it would be easier to maintain and manage their own fleet separate to the existing Government workshops. Initially all repairs and maintenance was done on a district basis; this meant maintaining one major repair centre for each district. As the programme grew, this concept became impractical both cost and management wise. In the case of the Rift Valley it meant maintaining and staffing nine separate workshops. A result of this was that many jobs such as engine and gearbox overhauls were being repeated far sooner than was necessary. With this view in mind, it was then necessary to establish a network of repair and maintenance depots for the RAR/MRP. In Kenya, this was accomplished on a Provincial basis, with one central workshop for major repairs supporting districts and field workshops. This system was established in 1989/90 and is now operating in three provinces. One example of this system is the Rift Valley Province where the establishment of one central or regional workshop and nine district base workshops are currently maintaining a fleet of 494 pieces of light duty equipment. Over the past year, with this system, an average fleet availability rate of 87% was achieved (see Appendix 1 for a three year comparison). The Regional Workshop output for the past year consisted of fifteen major overhauls of engines, gearboxes and differentials in addition to thirty-four major repairs to other components. All minor repairs and programmed servicing was carried out in the district workshops. Following is a brief description of the functions and responsibilities of these workshops: Role of the Regional Workshop The main activity of each Regional Workshop is to provide a major repair and rehabilitation service for all district base workshops within their catchment area. This includes the introduction and operation of a unit exchange scheme. Under this scheme, when the Regional Workshop receives a worn or damaged unit from the districts, it will immediately dispatch a working unit from the regional store, if one is available. The damaged unit will then be thoroughly inspected, overhauled and tested, where possible, before being placed in the regional store as available for exchange. All stages of dismantling, rebuilding and testing of a reconditioned unit will be monitored by the Regional Mechanical Officer Workshop as a complete unit (not disassembled). The exception to this is tractors, in which case the whole machine will be brought to the Regional Workshop. Therefore, tractor unit assemblies are non-exchangeable units and will be overhauled only at the Regional Workshop, and then delivered back to the district when completed and tested. Each unit assembly submitted for exchange must be accompanied by a District Request form giving details and reasons for exchange, including causes of any damage, excessive wear, etc. Serial numbers of all exchanged units will be systematically logged and equipment history cards updated as required by both District and Region. Units or unit assembles that should be available for exchange are as follows:
Brake drums Pressure plates Flywheels
Role of the District Base Workshop The main emphasis for District Base Workshop operations will be preventative maintenance, exercised through a programme of planned service schedules, together with regular equipment inspections and monitoring of equipment fleet condition. Every District Base Workshop will be responsible for undertaking the specified scheduled servicing of the equipment fleet under its control. All repair work will be limited to component replacement, removal and refitting of unit assemblies and adjustments only. Much of the servicing will be carried out during regular routine site visits. The District Workshop duties may be summarized as: P.M. servicing Brake systems In terms of operating the unit exchange scheme, the Officer-in Charge of the District Base Workshop shall have responsibility for assessing whether an assembly should be despatched for exchange. In case of doubt the Regional Mechanical Officer can be consulted. All worn units being despatched for exchange must be labelled with the unit serial number, details of equipment item being removed and a brief description of condition and cause of failure. It is very important for the efficiency of the maintenance system that the District Base Workshops DO NOT embark on repairs which are the responsibility of the Regional Workshops. Role of the District Field Workshop The District Field Workshop will service tractors, trailers and bowser only with the support of the District Workshop. The main emphasis in field workshop operations will be adjustments, inspection and reporting. Other items for attention will include tire and tube repair, wheel bearing adjustment and replacement, tightening and replacement of nuts and bolts and daily greasing of tractor trailer hitches. Any other action that is not specified will require permission of the Officer-in-Charge of the District Base Workshop. Equipment operators have responsibility for pre-start up checks and inspection, including refuelling, greasing, oil and water levels and tire pressure checks. The operators should be made aware of the important role they play in first level Preventative Maintenance. The field mechanics will also be responsible for undertaking a "walk around" reportable inspection of all tractors, trailers and bowsers. In establishing an equipment maintenance program of this type, several actors must be considered: Establishment of the physical workshops with appropriate tools and equipment This problem may be overcome by the use of existing Government workshops or new construction with donor assistance. As these are not sophisticated workshops the cost is not prohibitive. Work force - are they available and well trained? The three tier workshop system described above will help to minimize this problem by assigning the better qualified mechanics to the central workshop where the major repairs will be carried out. The lesser skilled mechanics would then be assigned duties in the district and field workshops for minor repairs and servicing. Tractor-trailer hitching systems The most common and preferred type of hitch is the hydraulic pick-up hitch with a pin and eye coupling as opposed to a rigid draw bar. Some manufacturers such as Ford and Massey Ferguson were able to supply this type of hitch as standard equipment. Others such as International were not. Because of this the MRP had to design a suitable hitch for its International fleet. After several revisions this hitch was developed to a satisfactory level and is not available from M.S. Trimborn Agricultural Engineering, Nakuru, Kenya (a sketch if this hitch appears as Appendix 2). As an option to the pin and eye style, a ball and cup type coupling could be used. In most cases with the ball type, wear would be reduced and would allow for better lateral movement. One disadvantage to the ball type would be higher replacement costs as in most cases these coupling units would have to be forged or imported. A second consideration for the hitch is the actual tractor to which it would be attached. A lot of the new model tractors in the low horse power range (45 hp) are being produced with lighter differential housings. This makes it virtually impossible to mount a robust hitch assembly. The 55 to 65 horsepower range still maintain suitable housings. One inherent problem is the constant loosening of the mounting bolts fixing the hitch to the tractor housing. This problem was most apparent with the International tractors where no suitable pick-up hitch was available from the manufacturer for MRP use. We overcame this problem by the use of one of the following methods: When the hitch is first fitted to the tractor and all of the mounting bolts are torqued to a specified tension, the heads of each bolt are spot welded to the hitch sub frame. The use of washers under the head of the bolt is not recommended. the second option is the use of studs and nuts in place of bolts. With this system, "locktite" is used on the threads in the tractor housing and again a sport weld is recommended between the nuts and the hitch sub frame (see sketches in Appendix 3). Tips for minimizing hitch pin and towing eye wear Sketch Trailers Many different designs and types of trailers have been used and experimented with over the years. Some of the more pertinent encountered with these earlier designs are as follows:
From years of experience with these trailers, one design for a standard three cubic meter trailer has been developed. This trailer was designed by MRP personnel in cooperation with a local engineering firm. Some of the improvements include an improved sub-frame design for better weight distribution which has eliminated sub-frame and drawbar breakage. It has sloping sides and front panel with an open back. This resulted in easier product removal and a lower profile for easier loading. An improved bucket design incorporating 3 mm plate and additional external bracing has eliminated body cracks and sagging floor panels. Axle load rate has been upgraded to 7000 kg and fitted with 900 x 20 tires. This has eliminated axle breakage and with the use of the 900 x 20 tires we have experienced fewer punctures also. These tires are manufactured in Kenya thus eliminating the extra cost of importing the more common balloon type tire. This trailer can easily be manufactured by any reputable firm or purchased from M.S. Trimborn Agricultural Engineering, Nakuru, Kenya. This current design has been in use for the past five years. On a fleet of 150 trailers an availability rate of 95% is being maintained. Only minimal maintenance is required to wheel bearings and towing eyes. NOTE:
For information purposes, a sketch and technical specification sheet for this trailer can be found in Appendix 4. Tipping trailers As mentioned earlier, the hydraulic tipping trailer met with very little success in the Minor Roads Programme. This was basically due to the high maintenance costs to the hydraulics, and excessive down time. In an effort to improve on the efficiency of equipment used in labour-based road maintenance, staff ant MRP Nakuru have been experimenting with a self-tipping non-hydraulic trailer. This trailer was designed and six prototype trailers were manufactured in Nakuru. These six trailers have now been working in the field for the past six months. The results to date have been fairly good. As there are still a few minor alterations to be made to the design and the field tests are not complete, no recommendations will be made at this time for this trailer. The Regional Office in Nakuru is hopeful that by this time next year they will be able to offer a successful design for a non-hydraulic tipping trailer. Procurement As stated earlier, one of the problems encountered was the use of unsuitable materials and poor workmanship in manufacturing. What is of prime importance in the procuring of equipment is that the supplier is capable of delivering quality goods. Secondly, clear and concise specifications should be supplied to manufactures/suppliers. Thirdly, during the manufacturing process there should be constant monitoring of work in progress by the client’s representative. During this monitoring special attention should be paid to such items as quality of material, welds and adherence to specifications. Below is a sample of such details to be included in a contract document for manufacturing trailers.
Technical specifications for 3 cubic metre trailer
3. Chassis: The middle member of the chassis shall be of 2 U channels of 160 x 65 x 6mm welded together with long stitch welds (except on joints) to form a box in cross section and is extended beyond the bucket to form the draw bar of 1130mm in length as per drawings. 4. Details: Stub axle type GS 6006-1 (axles 80 x 80mm) Axle related load 7000 kg.
Introduction The function of a supplier is to link customer requirements to suitable and available equipment. In other words, the conversion of a need into a practical and economic solution. Several very interesting needs were uncovered during the Mbeya and Lesotho conferences. These statements are reproduced below and we will attempt to link the need or problems stated to some possible solutions and suggestions: "Likely cost savings in grading by adoption of heavy tractor towed grader technology are in the order of 40% over existing methods" - reference Roads 2000, Lesotho Congress. "Adoption of tractor technology for the equipment operations would offer flexibility based on the simplest large power source: the tractors could be used for towing gravel haulage trailers, roller, bowsers and mobile accommodation when not grading. Standardization on tractors would significantly reduce spares costs and procurement problems. All the tractor attachments could be manufactured in Kenya" - reference Roads 2000, Lesotho congress. "Tractor/trailers have an economic haulage distance of 2 km - 5 km" - reference Mbeya Labour-Based Technology Report, February 1990. "The largest problem faced by all participants was finding a reliable supplier within the Southern and Eastern Africa region of a well designed, well manufactured trailer" - reference Mbeya Labour-Based Technology Report, February 1990. "Kenya has 25 260 km of gravel roads requiring maintenance, and a re-gravelling requirement of 3 160 km per annum. The average re-gravelling output over the last 5 years has been 240 km per annum" - reference Roads 2000, Lesotho Congress. Discussion Cost savings with towed graders Little can be added to the indisputable fact that towed graders do offer substantial cost savings over self propelled graders when applied to the maintenance of rural roads. The potential savings, however, can be eroded or totally eliminated if haulage equipment towing the grader is unsuitable for any reason at all. We offer some suggestions regarding minimum guidelines to ensure effective grading in terms of performance and equipment life: Motor graders are generally equipped with torque converter transmissions. This is done to provide efficient transfer of engine power to the drive wheels at all times. It therefore is logical to assume that if a haulage tractor can be provided with a torque converter type transmission, this would contribute greatly to the effectiveness of the grading operation. In most instances it will be necessary to have a haulage unit offering 4WD traction and adequate tyre options to provide good traction and tyre life. Normal open centre agricultural tyres are fine for ploughing but are not suitable for hard road surfaces, so it is normally preferable to use industrial tyres similar to those on self propelled graders. Heavy duty towed graders require adequate horsepower and it is suggested that a minimum of 110 horsepower be provided in order to efficiently tow a 5 tonne grader. It is essential that a heavy duty hitching device be provided on the tractor, not only to effectively handle the high loads which a grader will impose on the hitch, but also to ensure that there is weight transfer from the grader not only onto the rear driven axle but onto the front axle as well. It is futile to specify a 4WD hauler unless at least some of the weight is transferred to the front axle. Most agricultural tractors employ a simple swinging drawbar type hitch with hook and eye coupling. This tends to lift the front axle of the tractor. Both the haulage equipment and the towed grader need to be of robust design and manufacture and be as simple as possible to maintain. Repairs should be simple undertake as they are mostly done infield and costs should also be low. It is preferable to have a completely external hydraulic system incorporating external pumps, separate hydraulic tank and full filtration. Flexibility The tractor and drawn implement concept is well established and certainly offers many advantages over dedicated pieces of equipment. Not only is dedicated equipment expensive to purchase, but it is even more costly to have this equipment standing idle through lack of work. A system utilizing one prime mover and several drawn implements is therefore more cost effective. What needs to be avoided, however, when following the multipurpose route is to ensure that the equipment is adequate for the task intended. All too often multipurpose machinery is limited in it’s ability to do what is intended as well as being limited in terms of longevity. it is important to ensure that the drawn equipment is therefore well designed and manufactured to high structural integrity standards. The Bell range provides an exceedingly wide range of drawn implements and equipment, which is purpose designed for many rural road maintenance and construction applications. Standardisation This is an important aspect and should be viewed in conjunction with information relating to population of similar equipment in the country under consideration. Consideration should also be given to parts availability, parts pricing and sourcing of parts. Local manufacture Bell are in a position to supply, as indicated, a wide range of towed implements. We would be happy to work in conjunction with local manufacturers to ensure that maximum benefit is obtained from local manufacturing facilities and abilities, thereby reducing foreign exchange expenditure and providing additional local inputs. Economical haul distances We would agree with a maximum economical haul distance for a tractor of some 5 km, though this of course would depend very largely on the product being hauled and the road conditions involved. As the Bell hauler is purpose designed for haulage applications, it has a considerably higher road speed than most conventional and agricultural tractors. The normal safe road speed for Bell haulers is 40 km per hour. Economical haul distances can therefore be extended quite considerably before the truck option becomes more economical. We would suggest that haulage distances of up to 10 km -15 km be acceptable for the Bell haulage tractor, though this of course would be highly dependant upon the design and capacity of the trailer. Each application would have to be studied separately, but it would almost certainly be cheaper to utilize one 110-120 tip hauler over 15 km with a payload of 7m3 than to use two tractors and four trailers of 3m3. Where distance is greater than the loading time allows, one can use two 14 tonne trailers to one Bell hauler for even better economy. Fuel cost per tonne hauled is of prime importance. Trailer design Much has been said and written about the ideal trailer design for rural road and re-gravelling applications. While not denying the need for small trailers in some applications (this is perhaps where the animal drawn trailers come into their own), we feel that to employ even small contractors to haul trailers with capacities of as low as 3 tonne is highly uneconomical, and that considerably larger tipping trailers should be considered, even if they were of a design allowing for manual loading. Some criticism has been levelled at hydraulic tipping arrangements due to the possibility of contamination. A properly designed system could provide more than adequate protection from dirt ingress. We would suggest that the ideal trailer, especially for gravelling operations, be hand-loadable with a capacity of 5-7m3, hydraulically tippable and of single axle configuration. It should also be possible to hydraulically unhitch the trailer during the loading operation and to operate two or more trailers in any one application, to maximize the prime mover. Gravelling and maintenance requirements The re-gravelling task and maintenance through use of drawn graders would seem to be the biggest application for a mixed technology of labour-based methods and tractor towed methods. If the figures offered by Kenya are anything to go by, there must be hundreds of thousands kilometres of roads throughout Africa requiring re-gravelling and grading every year. Instead of providing each region with equipment which is capable of undertaking re-gravelling and grading in addition to the other more labour-intensive operations, we would suggest a complete re-gravelling/grading mobile team. The equipment would include two and four-wheel-drive haulers in combination with hand-loadable tipper, heavy duty graders, mobile workshop and accommodation units. When moving from area to area these units can be formed into a complete train, eliminating transport difficulties from site to site. Tow or even three trailers could be towed in one train dependent on local road ordinance regulations. The grader could be hitched behind a unit of mobile accommodation, while the tipper trailer could form up with the mobile workshop. Ideally this maintenance unit should be almost entirely self sufficient, and independent. The Mechanical Advantages of Bell Rigid Haulers Heavy duty chassis The fully fabricated main beam type chassis is constructed of the finest tensile steels available. The chassis is prefabricated on fully rotating jigs to ensure integrity of welds and alignment is maintained. This purpose design chassis allows for absorption of shock loads from rough terrain without affecting the major drive train components. Repair work and maintenance are easy tasks as access to the engine and transmission has been incorporated into the design, as is simple removal and installation of components. The axle A 10 tonne capacity, heavy duty driving axle improves ground traction, stability and production, while the planetary gear hub reduction system with full floating side shafts reduces stress on main drive line component. All this combines to reduce operating costs considerably. Brakes The simply yet effective braking system has been designed specifically for high speed haulage and maximum trailer loadings. Large diameter air operated brakes provide efficient brake capacity in all conditions and come equipped with a fail-safe park brake which applied and air released. Transmission The fully automatic transmission allows for easier operation by less experienced operators. The single stage torque converter, with lock-up clutches fitted to the larger models, ensures smooth clutch engagement efficiencies and optimum gear ratios provide the best method of transmitting torque to the drive train. This significantly speeds up haulage cycle times, enabling road maintenance teams to be quickly relocated between sites. Engine The Deutz air-cooled engine has proved itself over many years to be well suited to rural applications, where temperatures can be extreme and dust presents a major problem. Hitch assembly A heavy duty hydraulically-operated ball hitch is incorporated on all Bell haulers. As the hitch point is situated forward of the rear axle, weight is also transferred to the front axle for maximum stability and safety. Cab and body The Bell hauler incorporates a fully-enclosed cab as standard equipment, providing a safe and comfortable working environment for the operator. High tensile steel is used in the construction of the cab and body to minimize damage to mudguards and bonnet, as well as to protect the operator. Other factors When considering the purchase and specification of any equipment, be it the haulers or the towed items, certain other aspects need to be given further consideration. Ease of maintenance It should be borne in mind that the with equipment generally operating far away from an established workshop, the maintenance procedures need to be simple and easy to undertake even by unskilled workmen. Reliability Once again mechanical reliability is especially important as the equipment operates far from an established maintenance base. Mechanical reliability is therefore of the utmost importance i the maintenance team are to provide economical services. Longevity All too often the lowest priced equipment is purchased due to capital availability issues. It is not unusual for agricultural tractors to have a very limited life span. Experience over almost 20 years indicates an almost infinite economic life for the Bell hauler. The Rural Roads Department in Botswana report a life in excess of 10 years for their Bell haulers, and there is every indication that this can be extended almost indefinitely with interim overhauls. Many of original tractors manufactured 18 years ago have given in excess of 70,000 hours of economical production. This factor will obviously have a major effect on overall cost calculations over the machine life time. Back-up and support All too often lowest tender prices are accepted without due regard to the extent of locally available product support. It is important that technical expertise and readily available parts are available in the relevant country. The availability of alternative sources of supply of spare parts should also be given consideration. VI. Intermediate Equipment to Support Labour-based Roadworks: Development, Testing and Evaluation of Prototype Equipment By Robert Petts, Consultant Engineer, Intech Associates, UK SYNOPSIS Labour based techniques have been successfully and increasingly used in developing countries in the last two decades as a more appropriate alternative to heavy plant methods for roadworks. Significant improvements have been made in road construction and maintenance techniques, manpower and works management, training, and institutionalization through the efforts of the ILO and other committed parties. Developments in the intermediate technology equipment required to support certain operations have unfortunately received less attention. This paper reviews the current situation and needs, and some of the problems encountered in developing the support equipment required for labour based roadworks. Reference is made to recent experience on labour based pilot projects in Kenya and Namibia. Proposals are made for improving the availability of good designs and specifications for intermediate equipment, and guidance on their fabrication in developing countries. Introduction Over the past two decades labour-based road construction and maintenance programmes have been established in a large number of developing countries in Africa and Asia. As the costs of imported heavy civil engineering plant have risen and the problems associated with keeping them running have increased, the attractions (both economic and social) of using local labour resources have become more convincing. The International Labour Organization (ILO) have contributed significantly to the establishment and success of many of the labour-based programmes through assistance and support in the development of appropriate technical and management approaches, and institutional framework and training. During the initial years of development considerable efforts were made to develop designs and specifications for the necessary handtools and intermediate equipment required to support the labour-based operations. The Rural Access Roads Programme (RARP) Technology Unit and others carried out important research and development in this area. Publications such as references 1, 2, 3 summarize the recommendations developed from this work. Local manufacture of low and intermediate technology items to support labour-based roadworks is the logical progression in the development of local resources. Many of the items of handtools and equipment can be manufactured locally. Although the capability varies from country to country, selective initiatives can improve capacity at relatively low cost. Local manufacture promotes self sufficiency, employment and sustainability. In recent years a range of problems has developed, constraining the efficiency of many labour-based programmes through the inadequate provision of hand tools and equipment. This is evident from evaluations of recent or ongoing projects. The author’s most recent experience has been gained on programmes in Kenya and Namibia, although the problems encountered are commonly found on other roadworks in Africa and Asia. Further work is now required to counteract these constraints to enable the most appropriate handtools and equipment to be procured and supported on all labour-based programmes. The importance of appropriate and good quality handtools was demonstrated by the ILO (Reference 4); labour productivity can be substantially reduced by the use of worn out, weak, the wrong, or poorly designed handtools. Even on labour-based programmes the procurement and operation of equipment and transport consumes a large portion of the funding. Reference 5 et al estimate that this amounts to 20 - 30 % on large programmes such as the Rural Access Roads Programme (RARP). Considering the range of problems discussed in this paper, there is potential to substantially reduce equipment costs on labour-based programmes through a concerted and rational approach to tackling the current constraints. The Current Problems Experience with the implementation or review of labour-based programmes in a number of countries (Reference 6,7 et al) has enabled some of the current problems to be identified. This section attempts to summarize the problems for discussion. The experience is based on a number of African and Asian countries and the problems are often common to a number of the countries. The constraints have been grouped for ease of identifying possible counter measures. General Procurement is often carried out by civil engineers or administrators with inadequate knowledge of mechanical engineering or fabrication materials, or by mechanical engineers with insufficient appreciation of appropriate technology requirements. A core problem is the lack of suitable products "off-the-shelf" in most developing or developed countries. Furthermore there are no international recommended standard DETAILED designs and specifications for key items of equipment for labour-based roadworks, that have been developed through experience or rigorous testing. The lack of standard designs and specifications often leads to unco-ordinated ad-hoc attempts to develop suitable equipment through local commissioning of prototypes. Unfortunately insufficient attention is usually paid to the process of planning, procuring, testing, evaluation of, and dissemination of the experiences of these prototypes. Usually there is no mechanical engineering expertise involved sensitive to the needs and constraints of the technology, i.e. the requirements that the designs must be:
Quality Labour-based roadworks usually require good quality handtools and equipment able to stand up to the adverse conditions experienced. Standard agricultural items available on the local market are usually adequate for their intended use, however they are often of inadequate quality for roadworks. The required high quality items are often no available "off-the-shelf"; requiring to be specially imported, or locally fabricated to order. Designs and specifications Many of the available designs and specifications are not sufficiently detailed to ensure a good quality and robust product from local manufactures. Some of the available design are not appropriate for local fabrication or for their intended use. Procurement system Most road authority procurement must be carried out through the government system. This usually requires the acceptance of lowest tendered price without adequate regard to quality. Where national standards are available they are often based on agricultural quality items and are usually only established for common items. There is sometimes resistance by tender boards (who often include representatives of local industry) to accept special conditions which exclude commonly available products. Procurement by tender often takes several months and local manufacturers will often only procure raw materials after being awarded contracts. The small markets for the products and raw materials, long supply lines from developed countries, bureaucratic importation procedures, weak local currencies and inflation, make prediction of delivery dates and costs difficult for local manufacturers. It is of little surprise that the suppliers often discover that they are eventually unable to provide the manufactured item at the original tendered price and make a reasonable profit. Withdrawal from tender commitment or late delivery are also commonly experienced. Local manufactures Local manufactures often experience some of the following problems:
There are usually inadequate acceptance/handing over procedures to ensure that all production models are to an acceptable standard (an approved prototype of detailed designs and specification). Similarly, effective warranties or arrangements to rectify faults on locally manufactured items are rarely included in the procurement contracts. There are usually insufficient arrangements for the stocking or provision of spare parts. Developed country manufactures Many of these manufactures no longer offer low or intermediate technology handtools and equipment, probably for a range of reasons such as: High home labour costs Weak, irregular or distant markets Payment or foreign exchange problems More attractive returns from supplying developed world markets. Recommendations for improvement of handtool and equipment provision This Section makes some recommendations for improving the environment for handtool and equipment provision for labour-based programmes. With the trend towards greater use of the private sector for roadworks in developing countries, it swill be particularly important to provide proven designs to contractors in which they can confidently invest. Handtools Establish and keep up-to-date a register of manufactures worldwide who supply construction quality handtools for roadworks. Promote the inclusions of specifications for construction quality handtools in national standards in developing countries, including testing and acceptance procedures. Equipment establish and keep up-to-date a register of manufacturers worldwide who supply low/intermediate technology equipment for roadworks. Co-ordinate the identification of needs, planning, securing funds, procurement, testing, evaluation of, and dissemination of experience for, prototype items for equipment and handtools. Mobilize the experience and resources of established institutions, e.g. road and agricultural sector research establishments, and universities with a research and development capability. Encourage independent testing and evaluation of designs by these organizations. Establish international specifications and detailed designs for equipment for labour-based roadworks. Interim/provisional guidelines be available if insufficient knowledge or experience currently exists for a particular item. Urgently promote the establishment of specifications and designs for the items of equipment most commonly used on labour-based programmes. Figure 1 makes recommendations on these priorities. Figure 2 indicates the potential for developing tractor based attachments to support labour operations. Most of these items could be fabricated in developing countries under suitable arrangements, or could be locally assembled with the provision of Knock-Down-Kits. Figure 3 includes other items of equipment for which detailed designs and specifications should be readily available. Establish guidelines for the procurement process for non-standard, prototype or locally fabricated items of equipment, including: initial specifications/briefs, identification of possible suppliers, supplier selection for bidding, documentation, tendering/negotiating, refinement/finalization of contracts, monitoring/testing/modification/acceptance during fabrication, acceptance procedures on delivery, arrangements for follow up warranty/support/spares. Promote the interest of tractor and attachment manufacturers in labour-based roadworks and the needs of the sector. Encourage their collaboration or initiatives in developing/refining designs. Promote the establishment of Knock-Down-Kits arrangements in countries with very limited existing indigenous manufacturing skills. Establish recommended spares stocks to be provided with initial items of equipment for common equipment types.
References
Introduction By definition, labour-based road construction and maintenance methods consist of an appropriate combination of utilizing labour complemented with a limited use of equipment. Equipment for labour-based road works is mainly utilized for operations such as haulage of materials and water, compaction, grading and rock breaking. Well-designed and maintained tools and equipment are important as they determine the productivity as well as the quality of the works carried out. It is therefore important that the tools and equipment used for labour-based construction and maintenance activities are properly designed to stand heavy wear and tear, and the normal abuse of a road work site. The most common scenario is that 20% - 30% of total construction costs are attributed to the equipment use. However, 90% of all headaches of project managers are related to the use of equipment. The workers turn up and perform every day, but the equipment breaks down. Malfunctioning equipment is very often the most common item which jeopardizes the progress of a road project. ASIST collects and disseminates information on the design, use and performance of the equipment used by labour-based programmes in the region in order to provide better advise and recommendations to new projects. However, ASIST does not yet have complete confidence in which is well suited to labour-based road construction and maintenance programmes. Furthermore, experience has shown that it has been difficult to agree on standard choice and designs on equipment. This issue was further addressed by looking into the following key questions: Is commercially available equipment really suitable for labour-based road works? Are existing modified designs appropriate? How can appropriate designs be developed? How can appropriate designs be manufactured and procured? Specifications and Quality Assurance During the production of tools and equipment, it is extremely important to monitor the manufacturer in terms of quality assurance. Before a contract is awarded, it is important that the client makes sure that the company can effectively carry out the job (work-shop facilities, skilled staff, liquidity, etc.) Before production commences, all materials should be quality tested. During production, the quality of the works should be controlled at all stages of the manufacturing. It is also recommended that the stores staff or site supervisory staff keep a record on the lifetime and performance of tools from various suppliers. In addition to national design standards, the ILO has prepared design specifications for various handtools and equipment used for labour-based works. However, for various reasons some countries have now dropped their original design standards, which has resulted in the deterioration in quality of government purchases. Procurement Procedures Lack of design and quality specifications may present a problem for achieving a certain quality level on equipment. However, a more common problem is often due to organizational aspects. In many cases, government purchasing procedures represent a serious obstacle in obtaining the desired quality of tools and equipment. The project management staff may be fully aware of what specifications are required, but fail to convince the tender board or the procurement officers that the cheapest bid may not always be the best alternative. The issue of procurement procedures is not only limited to the government procedures in the country in which the works are carried out. Programmes which receive financial and technical assistance from bilateral donors, the World Bank and the UN-agencies, are obliged to follow the purchasing regulations of these organizations. In most cases, the purchasing officers of these organizations are not aware of the special demands and considerations which should be made when supplying equipment to labour-based programmes. Procurement procedures are very often the reason for the difficulty in standardizing the equipment fleet. This leads to increased maintenance costs since it forces the mechanical workshops to deal with a larger variety of spare parts. From the above, it is obvious that certain measures are required to obtain the desired level of quality and specifications for tools and equipment for labour-based works. The immediate solution would be to clearly specify these in the tender documents. If foreign aid is involved, these issues should be addressed in the project agreements between the donor and the recipient government. Correct use of Hand-tools and Equipment The optimal choice of tools and equipment also varies from place to place, depending on the site conditions, type of works carried out, type of soils, local skills, etc. Site supervisory staff are trained in the proper use and maintenance of tools and equipment. Since the labour is temporarily employed, they are not provided with any formal training in the use of tools and equipment. However, the supervisors are responsible for instructing the workers and ensuring that tools are properly used and maintained. The workers are often very conservative concerning the proper use of handtools. Local traditions lead to a reluctance among the workers to use new tools. In Lesotho, the LCU tried to introduce long wooden-handled shovels: however, this did not catch on, although it has been proven that long handles are ergonometrically better. Finally they had to accept what the workers wanted to use. Choice of Appropriate Hauling Equipment Much effort has been made in designing appropriate hauling equipment for labour-based road programmes. The main types of hauling equipment used are wheelbarrows, animal-drawn carts, tractors and trailers and trucks. Donkey-carts So far, it is only the labour-intensive district programme in Botswana which has successfully introduced the use of animal drawn haulage on a wide scale. It is believed that this method also has potential in other countries where animal-drawn transport is commonly used in the rural areas. Donkey-carts have been proven to be competitive for hauling distances up to 3 km. It should be noted that there are certain limitations to the method, such as hauling distance and the availability of animals in the vicinity of the road site. Secondly, the recent drought in Botswana reduced the use of donkeys since fodder became scarce. During this period many owners were not willing to hire out their animals. However, not that the drought is over, it has become easier to rent donkeys again and the programme is once again using donkey-drawn carts for gravelling purposes. Tractor and trailers The most common means of transport on labour-based road construction projects are 3 m3 trailers hauled by agricultural tractors. The great advantage of using trailers is that more than one trailer can be used fro each hauler. This means that while one trailer is transported to the site, another trailer can be loaded. Furthermore, the trailers provide a low loading height, which enhances loading carried out by manual labour. In Kenya, the experience is that the standard Masey Fergusson 65 Hp tractor is appropriate for hauling purposes. In other countries it is felt that the agricultural tractors are not sufficiently robust for road works. Some projects have experienced that the hauler requires an independent frame which bears the load imposed on the machine - not as agricultural tractors, where the engine is an integral part of the frame and carries part of the load imposed on the tractor. Several manufacturers can produce tractors according to specifications appropriate for labour-based works if requested, as long as the order is of a certain size and number of units. Bell Equipment in South Africa manufactures good quality purpose-built haulers: however, these may be on the large side for labour-based works are the 75 Hp and 10 Hp, but these models are too heavy and are similar to the heavier versions only with smaller engines. However, if requested this design could be modified if the market requires it. Experience has shown that agricultural trailers are not designed for road works. Instead, the Minor Roads Programme has designed a more robust trailer which has shown a satisfactory performance. This non-tipping trailer can be locally produced and provides a simple-but-durable design which stands up to the loads and strains imposed on the equipment. With the current solid design of the MRP trailer, it cannot be overloaded. It consists of 3 m3 bucket mounted on an A-frame, with a 7000 kg single axle and 900 x 20 truck tires. The loading capacity of the trailer corresponds to the applied task rate system.. It has neither side doors nor tailgate. Hydraulic tipping has been omitted, since this item very often breaks down. Decoupling of hydraulics on trailers in a dusty environment several times a day can easily ruin the hydraulics system. Trucks Trucks are used for hauling of gravel when the transport distances from the gravel sources are too long for effectively using tractors and trailer. The main disadvantage with trucks is that they are more difficult to load when using manual labour. However, this problem can be solved by proper organization of the gravel pit. Cost-comparisons Choice of appropriate equipment should only be done after a proper analysis of the various available equipment has been carried out. This calculation should be based on the current price levels of the various types of equipment in the country, as well as service and repair facilities, hauling distances, amount of work envisaged, availability of equipment from contractors, etc. Project staff do not carry out the required analysis to arrive at the optimal choice of hauling equipment for the specific conditions related to their project. As an example, the Rural Access Programme in Kenya ordered 500 tractors for short hauls, which are currently used for hauls of up to 20 km. Furthermore, very little data has been collected on cost and performance in order to compare the competitiveness of tractors and trailers versus the of trucks or other means of transport. In many cases, equipment orders for new projects are based on decisions made on already ongoing programmes replicating their choice of hauling equipment. This may lead to badly-made decisions, since a series of conditions may change from one country to another. Items such as import taxes, repair facilities and availability of domestic transport contractors and local manufacturers are important factors which determine the competitiveness of various types of equipment. As an example, Kenya has very competitive prices on tractors due to the fact that they are locally produced, and therefore exempt from import taxes. In the neighbouring country, Tanzania, tractors are not produced locally, leading to a less advantageous picture for tractor-trailer alternative. These cost comparisons should be carried out on a regular basis, complemented with a proper monitoring of the running and maintenance costs of the current equipment fleet the project possesses. Optimal Size of Equipment Compaction The most common compaction equipment used on labour-based road projects are pedestrian vibratory rollers. The labour-based programmes in Ghana and Zimbabwe are currently testing out the use of larger, self-propelled vibrating rollers. The advantage of the self-propelled rollers is that they are more comfortable to operate and they can maintain more easily a smooth camber. The main disadvantages are that they are more costly and due to the increased size, they are more difficult to transport. In addition, it is evident that more sophisticated rollers need a larger variety of spare parts which may lead to longer down time and reduced availability rates. In Ethiopia the pedestrian rollers are still preferred. On steep side cuts in mountainous terrain, it was experienced that, due to his elevated position, the operator on self-propelled rollers felt unsafe when compacting on the fill side of the road. Therefore they did not move sufficiently far out on the fill side, leaving the outer section of the road poorly compacted. When selecting appropriate compaction equipment, the size of the rollers should be carefully adjusted to the size of your operation. Once again, a proper cost analysis should be carried out, including taking into account available service and repair facilities in the country. This is even more important when involving small-scale domestic contractors for the execution of the road works. These firms do not possess a considerable amount of capital, and in many cases the most limited investment in equipment will represent a major economic venture. In such cases it is extremely important to select a set of equipment which (i) the contractor is able to finance and which represents and amount that can be recuperated in a not-too-long period, and (ii) can be used for other purposes and job contracts outside the road sector. Transport for Supervisory Staff Transport for site inspection is often considerable cost item on labour-based road projects. The means of transport used for this purpose ranges from bicycles to expensive four wheel drive vehicles. In Namibia the roads authorities have decided to introduce 4-wheel motorbikes for the site supervisory staff. Bicycles and motorbikes have been successfully used for routine maintenance inspectors in some road programmes. When supplying staff with this type of transport, experience has shown that the lifetime of this equipment has been considerably extended when it has been sold to the staff, thereby transferring the responsibility for mechanical maintenance to the supervisor. Towed Graders Zimbabwe has established a solid and positive experience on towed graders providing good performance and availability. The labour-based programme in Kenya is currently trying to replicate this in the Roads 2000 project1. The strategy of Roads 2000 is to maximize the use of labour for routine maintenance works only using equipment for activities where use of labour is not feasible. As a result, 5 tonne towed graders drawn by a 108 Hp tractor are used for grading the running of the road. The side drains are still maintained by labour. In Tanzania, trails showed that towed graders performed very well. Light grading of the running surface did not deform the camber. Rock Breaking Equipment Due to mountainous and rocky terrain, Lesotho has tried out several types of rock-breaking equipment. These studies showed that as long as it was technically possible, manual methods were cheaper than the use of equipment. However, the choice of optimal rock breaking methods relies on the amount and type of rock to be excavated. This activity must be tuned into the other site activities in order to avoid delaying other operations. In certain areas of Lesotho with long road sections of rock excavation, drilling and blasting are the only viable alternative. Fire on rock works well in Zimbabwe and Ghana: however, the method has failed when applied to some rock types found in Lesotho and Nepal. Role of Local Manufacturers The role of domestic manufacturers in the supply and maintenance of tools and equipment to labour-based road projects remains to be fully exploited in most countries in the region. A great deal of the tools and equipment used on labour-based road projects do not require any sophisticated technology and can be produced locally. In Sierra Leone the roads authorities experienced that locally produced machets manufactured from used vehicle springs performed better than imported models. Local manufacturers often have a limited production capacity. It is therefore important to plan well ahead when engaging small domestic suppliers. In some cases it may be necessary to split the order into several smaller quantities, thereby matching the size of order to the capacity of the manufacturer. A second problem for small suppliers is that they are more vulnerable to cash flow distortions due to delayed payments from the client. In some countries, local manufacturers are not interested in delivering to government agencies because they are unable to pay on time. Previous efforts have shown that to further involve the local manufacturing industry requires a solid effort in terms of identification of suppliers, quality assurance, follow-up on payments, etc. The ILO should play a stronger role in promoting the use of local manufacturers. Preventative Mechanical Maintenance A preventative equipment maintenance programme is very important in order to achieve high availability rates and low equipment hire rates. In Kenya, recent studies have shown that the costs of mechanical maintenance were reduced by 35% - 40% after the new organization of the workshops was introduced in the Minor Roads Programme. For an equipment fleet of 500 units, the Kenya MRP requires a total of 26 qualified mechanics, 8 at regional level and 2-3 in each of the 9 districts. The mechanics and operators were trained at the Kisii Training School. In order to achieve good quality workshops, ad-hoc repairs on-site should be avoided as much as possible. Mobile repair units provide better quality maintenance and repair works. In addition, old equipment or parts of it should be replaced ahead of time before major breakdown occurs on site. The below table describes the lifetime of most common equipment in the Minor Roads Programme. Equipment lifetimes in MRP, Kenya
Maintenance of hand-tools is another major area where improvement can be made. It is important to train the tool-keepers in proper maintenance of tools in order to provide the workers with good quality equipment, thereby improving site productivity and the working environment. Further Action Co-ordination of Efforts There is a high demand for a co-ordination of efforts in research and development of appropriate design of light construction equipment for labour-based road works. Since the country programmes do not pass on their info to other programmes, tests and failures of equipment are often repeated. One of the purposes of establishing the Information Services of ASIST is to ensure that important experience gained in the various labour-based programmes is shared with other practitioners. ASIST in collaboration with a project can also initiate further research and development in specific fields as and when requested by its clients. However, in order to meet the demands and be able to prioritize its activities, ASIST needs an initial input in terms of ideas and initiatives from the managers of the various labour-based programmes. Several proposals for action are recommended in the paper presented by Robert Petts. Parties interested in carrying out these recommendations and in how to contribute to these issues should co-ordinate their inputs through the ASIST Technical Enquiry Service. Guide to Tools and Equipment There is a demand for guidelines on appropriate design and specifications for tools and equipment for labour-based road works. The ILO Guide to Tools and Equipment, published in 1981, should be revised and updated to include the recent developments of the technology. A great deal of experience has been gathered since the guide was first published. When introducing small-scale contractors to labour-based road works, it is particularly important to recommend proven designs of affordable equipment which can easily be maintained and allows for a certain flexibility of use in different sectors. If the ILO can provide detailed recommendations on design and specifications for tools and equipment, the project managers can use this as a reference to convince donors of what is required. Secondly, the revised version of the Guide should also describe appropriate procurement procedures for obtaining high quality equipment as well as guidelines for an increased involvement of local manufacturers. Project Background With financial assistance from DANIDA and SIDA, the Government of Zimbabwe, through the Department of State Roads of the Ministry of Transport, commenced in 1991 a road rehabilitation programme using labour-based methods and local resources. A first pilot site started in 1991 with technical assistance provided by a Danish consultancy firm, COWIconsult. Under this project, demonstration sites have been implemented, management procedures and administrative systems have been developed and tested and staff trained. This project was positively evaluated in 1993 and it has been proposed to expand and institutionalize these activities during a six year period starting mid 1994. SIDA and DANIDA will continue to provide financial and technical support, with 35% of the invest costs for the works being provided by the Government of Zimbabwe. Design Standards The design of these roads complies with the design standards used by the Department of State Roads for low-volume all-weather gravel roads. Figure 3.1 shows the cross section of the roads being constructed by the labour-based programme. The roads originally dirt tracks which are now upgraded to a 6 m carriage way with a 15 cm gravel layer. The roads alignment runs through tribal communal lands in slightly rolling and rocky terrain. Before the rehabilitation works, access was restricted to the dry season, with approximately 20 vehicles per day. The average daily traffic on the completed road section has been registered at 50 - 70 vehicles per day. Work Methods The projects are executed using labour-based construction methods complemented with light equipment for compaction and hauling of gravel and water. All earthworks are carried out by manual labour. Excavation of gravel, drainage, camber formation and installation of culverts is done by hand. Gravel is transported by tractor drawn trailers but loaded, unloaded and spread by labour. Compaction is carried out by Bomag pedestrian rollers. Gravel sources have been located in the vicinity of the road alignment. DANIDA Project The DANIDA assisted project started out with the upgrading of 28.7 km of Road 185 in Mudzi and Mutoko District. These works were completed in August 1993, the project commenced construction on Road 278 and has so far completed 21.2 km. The work has been carried out by extensive use of labour combined with a fleet of light equipment. Operating at full strength, the project has employed around 400 labourers, divided into two teams. Each team has 5 supervisors, with ne being in charge overall per team. This construction unit has experienced a maximum output of 4 - 4,5 km gravelled per month during the last half of 1992 and the beginning of 1993. The equipment pool consists of the following: 6 tractors MF 390 Table 3.1 and figure 3.2 and 3.3 summarize the costs and labour productivity achieved so far on this project.
Table 3.1 Production and Cost Data (Zimbabwean Dollars) Major Constraints Long and expensive water haulage during the dry season, particularly May to November 1992. Inadequate cement supplies for drainage works. Considerable down time on the tractors and trailers as the equipment got older. This is mainly related to the hitch, fuel injectors, rims and tires on the tractors, and lacking A-frame on the trailers causing the trailer axle to become loose, and cracking o the bucket. Figure 3.2 Figure 3.3 Senior staff salaries for engineers, and partly superintendents and stores assistants. Staff housing and office units. These are costed instead on a monthly hire charge basis. Expatriate staff salaries and accommodation, and supervision vehicle costs. Miscellaneous costs such as classroom rental, photocopier, computer, etc.
Each of the road construction projects has provided temporary employment to approximately 1300 unskilled workers recruited from the nearby villages, of which on average 25% were women. The duration of their employment has varied, with approximately 50% recruited for a minimum period of three months. Table 3.2 summarizes the total numbers employed and their gender distribution.
Table 3.2 Employment Data 90% of the works carried out by the unskilled labour has been organized as task work. The daily wage rate for casual unskilled labour is currently 8.73 Z$/day (US$ 1.34). With financial assistance from SIDA and with technical assistance provided by the Swedish consulting firm SWEROAD, rehabilitation works commenced in April 1993 on the 18 km Mutoko -Nyamazuwe section of Road 185. Currently this project is progressing with a monthly production of 4 km executed by two teams of 200 labourers. Each team is assisted by an equipment fleet consisting of 3 tractors and 6 trailers, 1 water bowser and 2 rollers (1500 kg). Average number of work days is currently 2269 wd/km. The project is expected to be completed by November 1993 at a final cost of 70 000 Z$/km (11 500 US$/km). |
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