Quantitative and qualitative workload assessment in steep terrain forest operations: fostering a safer work environment through yarder automation.

Many forestry roles have changed from being manual tasks with a high physical workload to being a machine operator task with a high mental workload. Automation can support a decrease in mental fatigue by removing tasks that are repetitive and monotonous for the operators. Cable yarding presents an ideal opportunity for early adoption of automation technology; specifically the carriage movement along a defined corridor. A Valentini V-850 cable yarder was used in an Italian harvesting setting, in order to gauge the ergonomic benefit of carriage control automation. The study showed that automating yarder carriage movements improved the ergonomic situation of the workers directly involved in the related primary tasks. However, the caveat is that improving one work task may negatively affect the other work tasks, and therefore introducing automation to a worksite must be done after considering all impacts on the whole system. Practitioner summary: Automation decreased the winch operator's mental workload while improving overall productivity. At the same time, the mental and physiological workload of the operator tasked with bucking were slightly increased. Ideally, winch automation should be coupled with bucking mechanisation to balance the intervention and boost both operator well-being and productivity.

Noise emissions in wood chipping yards: Options compared.

Industrial comminution is becoming increasingly popular, as the result of a growing demand for wood biomass. Such task is performed with either chippers or grinders, which are large, powerful machines, capable of generating much noise. In turn, high noise levels may have negative impacts on the health and comfort of workers, and of the people living in the surroundings of a wood fuel yard. This study gauged the difference between the two main technology options (i.e. chippers and grinders) in order to offer additional decision elements to wood yard planners. The chipper on test generated more noise than the grinder, due to its better ability to process wood and to transmit more energy into it. Since the chipper was equipped with less working tools and turned slower than the grinder, it generated its noise peaks at lower frequency bands. The grinder on test was more suitable for use in wood yards located near settled areas, and was an obvious choice whenever dealing with a diversified and occasionally contaminated raw material stream.

The effect of a slack-pulling device in reducing operator physiological workload during log winching operations.

The authors conducted a comparative test to determine whether the introduction of a hydraulic slack puller allowed reducing the physiological workload of operators assigned to log winching tasks. The tests were conducted in northern Italy, on the mountains near Como. The study involved five volunteer subjects, considered representatives of the regional logging workforce. Physiological workload was determined by measuring the operators' heart rate upon completion of specific tasks. The slack puller improved the efficiency of downhill winching, since it allowed a single operator to pull out the cable on his own, without requiring the assistance of a colleague. However, introduction of the slack puller did not result in any reductions of operator physiological workload. The main stressor when working on a steep slope is moving up and down the slope: pulling a cable is only a secondary stressor. Any measures targeting secondary stressors are unlikely to produce dramatic reductions of operator workload.

Exposure of mobile chipper operators to diesel exhaust.

The current boom of forest biomass is making mobile chippers increasingly popular among forest operators. This motivates concern about the potential exposure of chipper operators to noxious chemicals derived from diesel fuel combustion. The objective of this study was to determine operator exposure to BTEX (benzene, toluene, ethylbenzene, and xylenes) and polycyclic aromatic hydrocarbons (PAHs) generated from diesel combustion. This study sampled 28 mobile chipping operations in the Italian mountains, in order to determine professional exposure to BTEX and PAHs among chipper operators. IOM, Radiello®, and XAD2 samplers were used for the purpose. Operations were divided into industrial and small scale, the former based on powerful chippers with enclosed cabs and the latter on smaller machines without enclosed cabs. We could not detect any measurable exposure to BTEX, while exposure levels for PAHs were very low, especially for what concerned recognized cancer agents. That is likely related to work environment and organization because mobile chippers work in the open-air forest environment and in the presence of very few other machines. PAH concentration was significantly higher inside cabs than outside. None of the operators involved in this research was exposed to BTEX or PAHs above occupational exposure limits.

Determining the exposure of chipper operators to inhalable wood dust.

The study surveyed wood chipping operations in order to determine the exposure of chipper operators to wood dust and suggest suitable countermeasures. The survey included both industrial and small-scale chipping operations, all located in Central Italy, on the Apennine mountain range. During the survey, 60 samples were collected using standardized methods. For the purpose of the tests, each operator carried a wearable active sampler connected to a suction pump. When operators sat inside an enclosed cab, samples were also collected outside the cab in order to gauge the dust abatement effect of a protected work station. Exposure to dust varied widely with wood conditions and machine productivity, and only occasionally exceeded the 5mg m(-3) legal limit. Operators working inside a cab were three times less exposed than operators working outside, and they were never exposed to concentrations exceeding the legal limit. It is adviceable that people working full-time as chipper operators are positioned inside an enclosed cab, for limiting their exposure to wood dust. Small-scale operators are generally part-timers, which further reduces their long-term exposure.

Technology alternatives for tapping the pruning residue resource.

Four commercial harvesters were compared with respect to recovery of pruning residues for energy conversion. These harvesters were tested side-by-side on 17 test fields, totaling 15 ha. The test fields consisted of vineyards and apple and pear orchards. The residue yield was between 0.7 and 9 green tonne per hectare, at a moisture content from 37% to 48%. Yield was highest for the orchards, and lowest for vineyards. Harvesters collected the residues and moved them to the roadside at a cost of between 11 and 60€ per green tonne, depending on field conditions and technology choice. Single-pass harvesting was the cheapest, especially if applied through a dedicated tractor and a towed unit with a large integral container. Two-pass harvesting was the most flexible, but also the most expensive: it should be favored only when space, weather or other management constraints limit the application of the other systems.

Performance of a mobile mechanical screen to improve the commercial quality of wood chips for energy.

The study analyzed the performance of a mobile screening device for upgrading coarse wood chips to residential user standards, by removing oversize particles and fines. The machine was designed for transportation to forest landings, logistic terminals and plant chip yards. Average productivity was 1.9 oven-dry tons (odt) h(-1), corresponding to a screening cost of 28.5€ odt(-1). This figure was lower than the price increase obtained by upgrading industrial chips to residential user standards. Hence, screening offered a profit of 4.7€ odt(-1), or 16% of the original screening cost. The screening process was capable of upgrading chips from industrial to residential specifications, by reducing the incidence of oversize particles below the 1% critical threshold. Screening also allowed a substantial reduction in the content of fines. A similar effect was not verified for crushed wood, which failed to meet the specifications for residential fuel.

Relating safety, productivity and company type for motor-manual logging operations in the Italian Alps.

The study compared the performance of four different logging crews with respect to productivity, organization and safety. To this purpose, the authors developed a data collection method capable of providing a quantitative analysis of risk-taking behavior. Four crews were tested under the same working conditions, representative of close-to-nature alpine forestry. Motor-manual working methods were applied, since these methods are still prevalent in the specific study area, despite the growing popularity of mechanical processors. Crews from public companies showed a significantly lower frequency of risk-taking behavior. The best safety performance was offered by the only (public) crew that had been administered formal safety training. The study seems to deny the common prejudice that safety practice is inversely proportional to productivity. Instead, productivity is increased by introducing more efficient working methods and equipment. The quantitative analysis of risk-taking behavior developed in this study can be applied to a number of industrial fields besides forestry. Characterizing risk-taking behavior for a given case may eventually lead to the development of custom-made training programmes, which may address problem areas while avoiding that the message is weakened by the inclusion of redundant information. In the specific case of logging crews in the central Alps, the study suggests that current training courses may be weak on ergonomics, and advocates a staged training programme, focusing first on accident reduction and then expanding to the prevention of chronic illness.