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Ergonomics in Chilean forestry

E. Apud and S. Valdés

Elías Apud is Director of the Department of Physiopathology at the Ergonomics Laboratory of the University of Concepción, Chile.
Sergio Valdés is General Director of Forestal Millalemu, Chillán, Chile.

Wood production and exportation has long been a Chilean tradition. With sustained forestry growth over the past two decades, in 1990 Chile had an output of nearly 12 million m3 of wood, 90 percent of which was from Pinus radiata plantations. This has led to a corresponding rise in employment, the development of mechanized harvesting and a growing interest in increasing productivity through the application of ergonomics. This article summarizes the development of ergonomics in Chile as applied to selected forestry operations. It hopes to provide certain useful precepts for concerned forestry entrepreneurs and researchers.

FIGURE 1. A Chilean forest worker undergoing a stress test in a field laboratory

The ergonomics laboratory of the University of Concepción was set up in 1972 as an aid to teaching, research, information dissemination and technical assistance. From the outset, the forestry sector was accorded priority attention.

From the ergonomics standpoint, there were two distinct challenges. The traditional hand labour methodologies required improvement while appropriate technologies (those capable of maximizing worker productivity and minimizing the risk to worker health and safety) needed to be introduced and people made aware of their necessity.

The logic of these principles was irrefutable, but putting them into practice entailed a series of problems. At the enterprise level, most managers or owners were initially concerned that ergonomic improvements would lead to higher costs. The workers, on the other hand, tended to fear that ergonomic studies would be used to justify increases in their workloads. Therefore, the first step in an ergonomics programme needed to be a carefully thought-out information campaign to make all those involved- from workers to executives - fully aware of the objectives of ergonomic studies and the benefits offered by their application. This is why the laboratory has been working since 1972 to develop extension activities: oral presentations, practical demonstrations and courses on ergonomics designed for the various forestry sectors. Ergonomics courses for forestry and industrial engineering students have been equally important, giving the new generation of engineering graduates from the University of Concepción the opportunity to begin their professional life with a clear perception of the challenges involved in harmonizing the needs of industry with those of the workforce. This has smoothed the way for the ergonomic studies increasingly requested of the University by the forest industries themselves. More important, the findings of these studies are now being applied for the benefit of Chilean forestry workers.

FIGURE 2a. A dormitory in a forest logging camp in 1980...

FIGURE 2b. ...and an improved dormitory photographed in 1991

Chilean forestry workers

The first step in our ergonomics activities was a study of the specific characteristics of Chilean forestry workers. Before tools and working methods could be tailored to the worker, we first needed to know the workers' physical aptitudes. For this purpose, we set up laboratories near the work sites (Fig. 1).

The most important finding (Apud, 1978; 1983) was that the average physical aptitudes of this population were very good, in part because of natural selection and in part because of the in-service training inherent in their job. The very design of the hand-tools they used made certain anthropometric demands on their physique.

The studies also indicated that Chilean forest workers tend to be smaller than workers in other sectors of Chilean society and significantly smaller than forestry workers in northern Europe, North America or in other industrialized countries that produce forest machinery. Our third area of concern was the study of body composition, an important indicator of energy balance. A large number of workers were examined to estimate the proportion of body fat and fat-free mass (fat being the prime storehouse of energy) and body size (which is related to muscular-skeletal development). We were able to determine that fat mass in this slender population revealed sufficient dietary energy intake and muscular-skeletal development for body size and capacity to respond to effort. Readers interested in physical aptitude study methods, anthropometric characteristics and body composition are referred to Apud et al. (1989).

Notwithstanding these findings, the output of these workers, in contrast to their good physical aptitude, was low. The reasons for this needed to be looked into. One obvious hypothesis was that low salaries discouraged workers from applying themselves. Although this was clearly an important factor, field observations indicated that this was not the sole determinant. We therefore focused our analysis on the work environment.

The geographical characteristics of Chile make forestry work an isolated job, carried out far from urban centres. Most forestry workers are housed in camps which constitute a home away from home. In ergonomics, the usual concept is to apply ergonomic criteria to the job itself, i.e. how the worker, his tools, the working method and the physical surroundings interrelate.

However, we believe it is unreasonable to expect a forestry worker to be motivated, no matter how well organized his work, if his or her living conditions are poor. We looked for answers primarily in terms of the camp infrastructure and camp food.

Living conditions in forestry camps have generally been extremely poor. For example, a study undertaken in 1980 by the Superintendencia de Trabajo (Office of Labour Supervision) found that 41 of 42 forestry camps evaluated failed to meet minimum standards of hygiene and comfort. The camps in question belonged to contractors servicing larger enterprises. Since then, a serious attempt has been made to improve camp infrastructure and maintenance while some of the larger enterprises have funded studies for the design of prototypes and now directly handle the camp contract, which requires contractors to ensure good maintenance. Although our own observations indicate that many problems persist, it is only fair to acknowledge that progress is being made and that camps such as the one illustrated in Fig. 2a are being replaced by better facilities such as that shown in Fig. 2b.

Dietary requirements

Another of our prime initial concerns was to examine the diet of Chilean forestry workers. Studies published by Apud (1983) and Apud and Valdés (1986; 1988) showed that the diet varied significantly from one contracting firm to the next, ranging from a daily average of 2800 to 3500 kcal (11721 to 14651 kJ). There was also variation among the different types of worker. For example, power saw crews were generally better fed than less skilled workers. The same studies showed that the diet was made up primarily of carbohydrates, that consumption of fruit, vegetables and animal proteins was quite low and that there was also a marked vitamin A deficiency.

However, the energy balance studies by Apud (1983) indicated that Chilean forestry workers maintained adequate weight and body fat levels. Where their energy intake was insufficient, rather than calling on energy reserves, forest workers tended to reduce the amount of time devoted to work to the detriment of output and even their own income (they are usually paid on a piece-work basis).

The actual working time spent on a commercial logging site was approximately four hours whereas the working day lasted nine hours (Apud, 1983).

In the face of this evidence, some of the big forestry enterprises financed studies aimed at improving forest worker diets, in terms of both quality and energy intake. However, it was not easy to find a solution that also fulfilled the conditions laid down by these enterprises, i.e. affordable diets that would be easy to prepare under camp conditions where neither electric power nor clean drinking water were normally available.

The question that arose even before analysis of the diet's composition was how much dietary energy supply forest workers need. Further studies led to the conclusion that most forestry activities would require a daily supply of at least 4000 kcal (16744 kJ). However, this is only a very general figure as the environmental setting, the actual workload and specific individual traits produce a wide range of requirements. Given that it is not practical under camp conditions to prepare differentiated diets based on individual needs, it would seem preferential to calculate food needs in terms of those workers who have the highest energy requirements and, at the same time, educate workers to regulate their own intake (which will take much longer).

To design a menu, a study was carried out on a group of workers living in a logging camp. The food was prepared by a trained cook and modified in accordance with group preferences. The upshot was an affordable menu which supplied some 4000 kcal (16744 kJ) distributed in three meals per day and which incorporated nutritional components habitually lacking in the diet of this population. Although the meals were still rich in carbohydrates, they also included sufficient vegetables, fruit and animal protein to exceed the minimum recommendations of the Joint FAD/WHO Committee of Experts on Nutrition (1974).

We are clearly still far from an ideal diet: the menu is repeated from week to week and it has proved impossible to overcome the workers' opposition to any modification in the distribution of food over the course of the day. A recent study (spud and Ilabaca, 1991) of 50 enterprises catering to logging camps did show a net improvement in the diet, 43 percent having adopted diets similar to those originally proposed, albeit with some modifications. In addition to this, Chilean forest contractors are now offered catering services by specialized firms employing teams of nutritionists who are careful to ensure a balanced diet that is prepared under hygienic conditions. This study showed that 17 of the 50 enterprises evaluated had contracted such services.

Appropriate technologies for heavy manual labour

Before going on to describe the applied ergonomics surveys under way in Chile, it is important to mention that we have tried to adhere to the standard International Labour Organisation criteria (ILO, 1981), defined as the output that skilled workers can produce without excessive work in an average day or working day and based on the assumption that they know and accept the working method and are motivated to apply it.

The studies on appropriate technologies were done on study crews who operated just like any other group of workers but who had everything they needed to do the job correctly. During the working periods they lived in comfortable, clean camps and had adequate supplies of food prepared by a carefully trained cook. The camp also had such basic recreational facilities as television, playing cards and so forth. The crews were well trained for their specific tasks and basic work safety standards were also met.

To some, these conditions appeared to be a special privilege. However, there would be no point in carrying out studies on workers whose living conditions are poor, who lack the right diet, who are poorly trained and who are exposed to a high risk of accident. We believe that increased productivity is only synonymous with development when the lifestyles of the people who contribute through their work to higher productivity also benefit. Part of the income generated by increased productivity should be used to raise the workers' salaries and to improve living and working conditions in the camps.

Another concern, and this also has to do with the ILO's definition of standard output (ILO, 1981), was the criteria for determining excessive workloads. Traditionally, except in a few isolated instances, labour studies do not incorporate objective evaluations of the physical workload imposed by a specific task.

We therefore implemented techniques to evaluate energy expenditure and quantify cardiovascular load, using telemetric units to measure the heart rate (Figs 3a and 3b). For a detailed description of these techniques, the reader is referred to Apud et al. (1989).

In general, studies have focused on specific forestry production and management jobs. Following are some brief summaries of studies carried out on mid-height pruning (3 to 6 m) to analyse two different working techniques as well as a harvesting effort as an example of teamwork.

Mid-height pruning

Until recently, the traditional high - pruning method in Chile was to use a saw with a 6m handle. As Fig. 4a shows, the worker cuts the branches from the ground at quite a distance from the pruning area, a method that is bound to produce a source of flaws. Moreover, the job requires the neck to be held in a very awkward position and the shoulders and arms to be exposed to a heavy static load. One alternative is to use pruning ladders, bringing the worker closer to the job so that he can cut with a proper saw (Fig. 4b). This aids and improves cutting while reducing work posture problems. There is a higher risk of accident, but these can be avoided with effective designs (e.g. fastening the ladder to the tree).

A study crew of ten tree trimmers was used to make a comparative evaluation of the two systems of work. The two stands were very similar, as were climate and terrain. The physical load for each worker was estimated by measuring the heart rate (cardiac frequency) once every two minutes throughout the day. In Chile, heavy labour is defined as that which raises the heart rate above a daily average of 115 beats per minute in young workers (less for older workers) (Apud et al., 1989). Fig. 5 gives a graphic example of heartbeat monitoring throughout one day of tree trimming.

The findings showed that tree trimmers using a ladder to prune could trim an average of 125 trees per working day, whereas a worker on the ground covered only 96 trees per working day. In both instances, the average heart rate throughout the day was a highly comparable 100 heartbeats per minute, quite acceptable for an eight-hour working day. More important, the figure was no higher with the more productive method, even though tree trimmers had to climb up and down the ladder. This was because pruning from the ground required constant movement to manœuvre into a position where the branches could be seen. Working with a tool held over the head was another factor. Pruning from a ladder also produced a much better quality cut. The workers mentioned that they did not experience arm or leg fatigue, while neck and shoulder complaints were fewer. In conclusion, the ladder method was recommended because of these advantages and many forest enterprises have now adopted it as their method of choice.

Forest harvesting as an example of teamwork

Traditionally, harvesting in Chile is done by a crew: a power saw operator fells the tree and a gang of debranchers remove the branches. In the next operation, a choker setter attaches a choker (a wire rope with a noose) to the tree stem so that it can be skidded by tractor to the landing. At the landing another worker removes the choker. The stems are then cross-cut by other power saw workers and the logs are placed in piles by as many workers as there were debranchers. There are many variations, including the level of mechanization, but the crews are usually organized as described into ten-member teams.

On the basis of an evaluation of a traditional, clear-cut harvesting operation, Apud et al (1990) concluded that all in forest jobs (felling, debranching and winching) were much heavier than those done in the log yard. They recommended rotating the jobs among the workers and also examined the possibility of mechanized debranching with power saws.

At the time, some interested forest enterprises had contracted the services of a Swedish organization which sent trainers to Chile to introduce a new method. Under the new system, two power saw workers fell and debranch in the forest while a third cross-cuts the logs in the yard and another four workers do the remaining work a system which reduces the crew to seven. The trees are removed from the forest to the yard with a tractor. As this is an increasingly popular method, it was decided to carry out a study to address certain concerns that had arisen. The findings of Apud et al. (1990) showed that felling with power saws was not exactly a light activity. For this reason, if the fellers also debranched, the work could become very heavy. On the other hand, it was demonstrated that power saw crosscutting was a lighter job than power saw felling, so it appeared logical to recommend that the jobs be rotated. Since the normal practice is for two power saw operators to fell and debranch in the forest while just one does the cross-cutting in the yard, a three-stage rotation system was implemented: each of the three power saw operators fells and debranches for two-thirds of the day and cross-cuts for the remaining third. A comparison was made with workers felling and debranching all day long, the results of which are shown in the Table. As the table shows, rotating the work raised a worker's daily output as well as the hourly output of the tractor, which is the most costly item. At the same time, the average heart rate was reduced by ten beats per minute.

FIGURE 3a. A forest worker being tested for heart rate with a remote transmission device produced in Chile...

FIGURE 3b. ...the signal is received end recorded by the ergonomics researcher

FIGURE 4a. Using a ladder to trim was found to be more energy efficient and also more productive than using a long - handled saw


FIGURE 5. Variations in heart rate during the working day for a 35-year- old forest worker in Chile. Note interruption of testing during the lunch hour.

The increased daily output of nearly 10 percent was highly revealing given that the forests, terrain and climate where these evaluations were made are very similar. Since the workers are paid on a piecework basis, they initially rejected job rotation because they thought it would result in more "down" time. Once they got used to the system, however, they became enthusiastic, as they were able to earn more money with less effort. It is important to point out that only the power saw operator has been studied so far. There is some risk that augmenting the output of power saw operators might make other harvesting tasks very heavy, entailing asks for the workers. Research is now under way to determine a balanced configuration for the work crew as a whole.

Future challenges

The changing pattern of forestry work in Chile and the prospects for its growth have made it clear to some entrepreneurs that, to achieve increases in productivity, work must be made safe and attractive. Better salaries are also primordial. One of our current concerns is thus to consolidate a research effort designed to achieve standard outputs based on ILO criteria (ILO, 1981). This is a complex problem: such references must be worked out in terms of the physical workload that workers can tolerate without tiring as well as in terms of the job to be done and taking into consideration any obstacles that terrain or climate may present. To succeed, studies need to be carried out in forests that involve gradations of hardship, as the functions obtained must reflect the situations to which the worker is exposed. On the other hand, if all the variables are considered, it is possible to derive functions that can be used to predict variations in output with a very small margin of error.

TABLE. Comparison in-forest work1 systems



With rotation

Without rotation

Output per day (m3)



Output per hour of tractor operation (m3)



Average heart rate per minute



1Felling, debranching and cross-cutting.
2The average output and heart rate for power saw workers who did not rotate jobs during the day (but who felled and debranched all day long) compared with the heart rate and output achieved under the rotation system where felling and debranching were undertaken for two-thirds of the day and cross-cutting for the remaining third. The output shown was the average for a seven-member crew, three of whom were power saw operators.

A detailed discussion of models developed to date would be beyond the scope of this article but we do have some highly meaningful, reproducible equations for estimating the output of various jobs and these are now allowing us to study different salary systems. To date, the best option seems to be a fixed salary with production bonuses that workers can attain without endangering their health or safety through overwork.

The other challenge we face is the increasing mechanization of forestry work. With few exceptions, cost (tied to the possibility of increasing production) is still the ruling criterion in our milieu. Behind each machine, however, stands the worker who operates it and whose adaptation largely determines whether the technology will be put to proper use. We believe that sound technological progress means creating greater awareness among engineers and planners and that the ruling criteria need to be modified. This is the task in which we are currently engaged.

As an epilogue, it is interesting to point out that the road has not been an easy one and that we have not made much progress. Possibly, many developed country research workers interested in the same topic may have found the road hard. The study of people in the workplace demands a serious approach and our limited resources are often a constraint. Sometimes the research done in our countries is criticized for the simplicity of the methods employed. Even knowing that more accurate alternatives are available, we still need to remember that measuring workers and workplaces is only a means to an end: the end is a better working environment, which can often be achieved simply by using common sense.

Ergonomic studies in Chile have been developed almost entirely with local resources. Many difficulties were encountered in the early work but, once the first results appeared, the enterprises began to help finance the studies themselves. This helped us to improve our methods of evaluation gradually and to try to make efficiency compatible with workers' wellbeing. One thing makes the future look optimistic: the Grupo de Producción Forestal has been formed by 17 major enterprises, coordinated by the Fundación Chile. This group, devoted to the study of various forestry production questions, is financing a project on human resources which will provide a broader context for the discussion, analysis and solution of the main ergonomic problems in Chilean forestry.


Apud, E. 1978. An application of physiological anthropometry to a study of Chilean male workers. Thesis. London, Loughborough University.

Apud, E. 1983. A human biological field study of Chilean forestry workers. Thesis. London, Loughborough University.

Apud, E. & Ilabaca, C. 1991. Diagnóstico del estado actual de la mano de obra en algunas empresas de servicio. In Actas del Tercer Taller de Producción Forestal. Concepción, Chile, Fundación Chile.

Apud, E. & Valdés, S. 1986. Use of ergonomics to improve workers' conditions in a Chilean forest enterprise. Proc. XVIII IUFRO World Congress. Ljubljana, IUFRO.

Apud, E. & Valdés, S. 1988. Perfil del trabajador forestal chileno. In Actas del Primer Taller de Producción Forestal. Concepción, Chile, Fundación Chile.

Apud, E., Bostrand, L., Mobbs, I. & Strehlke, B. 1989. Guidelines on ergonomic study in forestry. Geneva, ILO.

Apud, E., Coffre, M., Vergara, N. & Burgos, R. 1990. Workload and output in different activities during final cut. Proc. XIX IUFRO World Congress. Montreal, IUFRO.

ILO. 1981. Introduction to work study. Geneva, ILO.

Joint FAD/WHO Committee of Experts on Nutrition. 1974. Handbook on human nutritional requirements. FAO Nutritional Studies No. 28. Rome, FAO.

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