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Vibration levels and daily vibration exposure while using different tools in a forest cleaning

Vibration levels and daily vibration exposure while using different tools in a forest cleaning Forest cleaning, being an operation that requires investment, but the return on investment is due for the next genera- tions, utilizes tools and methods that mostly haven’t been humanized. Harmful vibration is still present in today’s forestry operations, and new tools provide possible reduction of exposure to vibrations. Petrol chainsaw and battery chainsaw (late cleaning) and billhook, machete, and battery shears (early cleaning) were used and observed in this study. Vibration levels were measured and assessed using validated Brüel & Kjær 4447 vibrometer which complies with the ISO 8041:2017 standard. The measurement was performed according to the recommendations of ISO 5349-1:2001 and ISO 5349-2:2001 standards. Vibration exposure was assesed using work sampling method on the obtained video recordings in order to calculate relative shares of different work elements. Results show that hand tools (machete and billhook) are causing the highest vibration levels, while battery shears cause the lowest. Bat- tery chainsaw causes higher vibration levels while cutting, but lower daily vibration exposure than petrol chainsaw. A detailed revision in the classification of tools is needed, considering their ability to produce and transmit harmful vibrations to the operator. Using the current classification, the daily exposure to vibration of workers in early forest cleaning is high above legislative values. Key words: forest cleaning; hand tools; battery tools; vibration levels; vibration exposure Editor: Miroslav Hájek eters that are very important for the future structure of 1. Introduction the stand (Anić 2007). Forest cleaning is one of the work processes of forest Forest cleaning requires n fi ancial investment, and the tending that is carried out in the developmental stages results of work in the form of a quality stand will only of saplings and young trees, this work process removes be exploited by future generations. Therefore, since this from the stand everything that is considered poor quality is a silvicultural procedure that does not bring direct and superu fl ous for the stand future development such as financial income, the improvement of these operations cancer, bent, forked, broken, branched, damaged trees, was not a priority, and the methods and tools used in trees with abnormally developed canopy, trees with these works are outdated (Bačić et al. 2019). Further- broken, damaged or deformed top, shoots, overgrowth, more, some studies state that, unlike wood harvesting trees deformed in the various shapes, etc., therefore for- operations which are highly mechanized and use efc fi ient est cleaning has the character of negative selection (Anić mechanization and equipment, silvicultural operations, 2007). especially forest cleaning, are performed by manual or Forest cleaning is done in the early years after felling motor-manual methods involving a high proportion of or artic fi ial rejuvenation to eliminate competitive vegeta - manual labor (de Oliveira et al. 2014). In Croatian for- tion that outgrows the young or planted trees (Thompson estry, sickles, machetes, and billhooks are used in early & Pitt 2003). The rapid growth of stronger breeding spe- forest cleaning, and so-called “silvicultural” chainsaws cies after harvest requires an early cleaning procedure are used in late forest cleaning where hand tools are not in artificially or naturally rejuvenated stands to ensure an apropriate tool. optimal sapling growth (Jobidon et al. 2003; Thompson Mechanical forest cleaning can generally be divided & Pitt 2003). Cleaning regulates the stand shape by inu fl - into two parts according to the diameter of the trees and encing the type, shape, and ratio of the mixture, param- the tools used: manual cleaning (early forest cleaning) *Corresponding author. Zdravko Pandur, e-mail: zpandur@sumfak.unizg.hr © 2022 Authors. This is an open access article under the CC BY 4.0 license. M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 and motor-manual cleaning (late forest cleaning). Dur- measures intended to reduce to minimum exposure to ing manual cleaning, the worker holds a one-handed bill- mechanical vibration. Should workers be exposed above hook or machete in one hand, and with the other hand the exposure limit value, the employer shall take immedi- bends a tree that will be cut down for easier cutting. Two- ate action to reduce exposure below the exposure limit handed billhooks are more common due to the longer value. Due to the aforementioned harmful effects of range and stronger cutting force. In that case, the worker vibrations, the working hours of workers on chainsaws can use a two-handed billhook either with one or both are regulated in the Republic of Croatia, more precisely hands. Sometimes more swings are needed to perform according to the Ordinance on Occupational Safety and in order to cut. After cutting, the worker lowers the cut Health in Forestry (1986), a worker may not work effec- tree from the canopy zone and lays it on the ground. The tively with a chainsaw for more than four hours a day. distribution of felled trees is not uniform, trees located on There are many inu fl encing factors on which the level, the edge of the silvicultural trails are placed on those trails transmission, and exposure to vibration depend. Accord- however, felled trees within the cleaned area (bounded ing to ISO 5349-1:2001 (2001), the risk of consequences by silvicultural trails and haulage tracks) are distributed depends on the level of vibration, duration of exposure, according to the further needs of workers. Sometimes and frequency. Lower saw mass causes higher measured most of the felled trees are disposed of in a forest gap to vibration levels (Malchaire 2020). Increasing the stiff- give the worker more freedom of movement and access ness of the spring increases the natural frequency of the to other trees. system, while increasing the mass reduces the natural In the operations of cleaning even-aged stands in frequency of the system (Bower et al. 2022). The grip which hand tools can no longer be used, a professional strength of a chainsaw handle, which affects the trans- chainsaw of smaller dimensions and smaller mass is mission of vibrations to the hand-arm system, depends mainly used. In such stands, some trees that can be char- on the worker’s work experience, work operation, and acterized as overgrown reach over 20 cm in diameter on hardwood. Taking this into account, the grip is stronger the stump, so the use of a chainsaw in such cleaning work in less-experienced workers, in felling and sawing, and in is necessary. Usually, the r fi st cut is at an angle and at the the wood of higher hardness (Malinowska-Borowska et height of the worker’s shoulder, so that the upper part of al. 2011; Malinowska-Borowska et al. 2012; Malinowska- the tree can “slip” from the lower part. Then, if necessary, Borowska & Zieliński 2013). According to ISO 11681- the worker makes one or two more cuts in the same way 1:2011 (2011), the main factors affecting the level of until the canopy is lowered to the ground. The worker vibration in chainsaws are mainly dynamic forces in the then makes another horizontal cut in the stump of the motor, cutting mode, unbalanced moving parts, impacts remaining part of the tree. in gears, bearings, and other mechanisms, and also the Since the introduction of chainsaws in forestry, interaction between worker, chainsaw, and wood being numerous studies have reported signs and symptoms cut. Although chainsaw parts degrade with years of use, associated with vibration exposure while working with Landekić et al. (2020) concluded that age, i.e. years of use a chainsaw in forestry (Miura et al. 1965; Axelsson 1968; does not affect the level of vibration in used petrol chain- Barnes et al. 1969; Taylor et al. 1971). There are many saws. Studies (Colantoni et al. 2016; Neri et al. 2018; Poje synonyms for diseases caused by vibrations, the most et al. 2018; Huber et al. 2021) indicate signic fi antly lower common is the so-called “White finger disease” or sec - noise and vibration levels in battery chainsaws compared ondary Raynaud’s syndrome (Tambić Bukovac & Šenjug to petrol chainsaws of the same class. Goglia et al. (2011, Perica 2017). Numbness in the hands and arms, tingling 2012) in their study of the work with chainsaw silvicul- in the fingers, and deterioration of tactile perception tural operations record the daily exposure of workers to have been detected in workers who have been exposed vibrations above the warning limit and in some cases 2 2 to hand-arm vibrations (Seppäläinen 1972; Araki et al. 4.3 m/s and 4.5 m/s . 1976; Brammer & Pyykkö 1987). Hand-arm vibrations In addition to chainsaws that are used in motor-man- cause disorders in the blood supply to the fingers and in ual cleaning, and are a well-known and researched source the peripheral nerves of the hands and arms (Neri et al. of vibration, tools used in manual cleaning methods 2018). Workers exposed daily to excessive vibrations (billhook and machete) can also have a negative impact transmitted to the hand-arm system could suffer, on on worker health. The level of vibration is significantly long term, blood flow disorders in fingers and disorders affected by the type of handle with which the tool is of neurological functions and movements of hand and equipped. Hardwood handles (ash, hickory, and oak) arm (Forouharmajd et al. 2017). with a straight wire that is parallel to the tool blade trans- The daily vibration exposure values for the hand-arm mit less vibration to the hands of workers than fiberglass system specie fi d by EU Directive 2002/44/EC (2002) are and other synthetic handles (Beckley 2019). Kocjančić prescribed as a daily exposure action value of 2.5 m/s , (2018) states the length of the handle and the material and a daily exposure limit value of 5 m/s . Once the expo- as the main factors in the transmission of vibrations on sure action value is exceeded, the employer shall establish chopping axes. As an alternative to the manual method and implement a program of technical and organizational of forest cleaning using hand tools, intensive research on 50 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 the use of battery shears is being conducted in Croatian than one way were filmed using a small hand-held action forestry (Bačić et al. 2019). Bačić et al. (2020) report camera in order to perform time and motion study. This significantly higher levels of daily exposure to vibration resulted in a total of 40 hours of video material. A total of A(8) when working with a one-handed billhook than 8 hours of working intervals using a two-handed billhook, when working with a chainsaw. 16 hours of working intervals using a battery chainsaw, Therefore, the aim of this paper is to evaluate and and 16 hours of working intervals using a petrol chain- compare new battery tools and conventional tools used saw were recorded. Machete and battery shears were in forest cleaning from an vibration exposure standpoint. always used one-handed and those working intervals were not subjected to video recording. However, in all the working intervals in early forest cleaning, a number of swings/cuts was obtained using a simple mechanical 2. Materials and methods click counter. That was done in order to simulate the same 2.1. Observed tools and workers work tempo when measuring vibration levels generated by those tools. In the early cleaning, Stihl ASA 85 battery shears with Time and motion study was required in order to AP 300 battery, a two-handed billhook, and a machete accurately assess daily vibration exposure in the tools were used. While in late cleaning Stihl MS 261 petrol that are used in more than one way. Huber et al. (2021) chainsaw and Stihl MSA 200 battery chainsaw with AR in their study estimate that cutting work while using pet- 3000 backpack battery were used (Table 1). rol chainsaw and battery chainsaw in cleaning accounts Four male forest workers on four worksites were for one-third of total productive time. A work sampling involved in the measurements ranging from 35 to 59 method was used on the obtained video recordings in years. order to calculate relative shares of different work ele- ments within 4 hours of working intervals daily. During a short review and with experience from the previous 2.2. Worksites research (Bačić et al. 2020), an approximate percent- The first two worksites represented early forest clean - age of perceived working activities within one working ing conditions, and the second two worksites represented interval was determined, and after that, the review of the late forest cleaning (Table 2). entire recordings was started using the method of work sampling. For a 95% confidence interval, the required number of observations and recordings of work elements in one working day was calculated using equation 1. 2.3. Work dynamics, time and motion study ͲͲ͸ͳ ൈሺ ͳെ ݌ሻ ܰ ൌ On all worksites, workers were instructed to work with [1] respect to the defined work dynamic which was 30 min N – required number of observations; of work followed by 15 min of rest, with one 30 min rest p – percentage share of the least represented work element after 4 working intervals. Workers would not change the (calculated by previous short video review). tool in one working day which lasted 6 hours and 15 min- The observation interval was calculated from the ratio utes, of which 4 hours were working intervals. Working of the total duration of the video recordings in seconds intervals with tools that could be used or held in more Table 1. Main tool features. Tool Features ASA 85 battery shears Mass of 0.98 kg, maximum cutting diameter 45 mm, declared vibration level of 2,5 m/s Two-handed billhook Length of 125 cm, mass of 1.43 kg, beechwood handle Machete Length of 61 cm, mass of 0.4 kg MS 261 petrol chainsaw Mass of 5.2 kg, bar length of 37 cm, Rapid Super chain, declared vibration level of 3,5 m/s on both of the handles 2 2 MSA 200 battery chainsaw Mass of 3.3 kg, bar length of 30 cm, Picco Micro 3 chain, declared vibration level of 4,6 m/s on the front and 3.9 m/s on the rear handle Table 2. Worksite description. Location Description A young stand of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea Matt.) with admixtures of sycamore maple (Acer pseudoplatanus Worksite 1 L.) and european ash (Fraxinus excelsior L.) in the developmental stage of young trees. The terrain was of southern exposure, with a slope of 9–14%. A young stand of pedunculate oak (Quercus robur L.), common beech (Fagus sylvatica L.), and common hornbeam (Carpinus betulus L.) in the develo- Worksite 2 pmental stage of young trees with developed weed vegetation on the entire surface. The terrain was without slope. Young stand of common beech (Fagus sylvatica L.). Other types of trees include common hornbeam (Carpinus betulus L.), common birch (Betula pendula Roth), and sycamore maple (Acer pseudoplatanus L.). The stand was in the developmental stage of young trees. The soil was covered with Worksite 3 leaves, without bushes and ground growth. The presence of common birch of larger breast diameters was pronounced. The terrain was of southwestern exposure, with a slope of 8–12%. A young mixed stand of pedunculate oak (Quercus robur L.), european ash (Fraxinus excelsior L.), field maple ( Acer campestre L.), and field elm (Ulmus minor Mill.) mixed with common hornbeam (Carpinus betulus L.), white willow (Salix alba L.), and fruit trees. The developmental stage was of Worksite 4 young trees. The stand was medium to densely overgrown, with a heterogeneous mixture-quality ratio. The soil was overgrown with ground growth and hawthorn (Crataegus spp.) and blackthorn (Prunus spinosa L.) bushes. The terrain was without slope. 51 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 and the required number of observations for the least rep- ate vicinity of the operator’s hand (Fig. 1). Simulation resented work element. For videos of early cleaning (only of work in controlled conditions with one-handed tools with a two-handed billhook) the observation interval was was performed with the right hand as the dominant. The 8 seconds with 2 perceived elements, while for videos of vibrometer was calibrated by an accredited company, later cleaning with a petrol chainsaw it was 3 seconds and the measurement was performed according to the with 5 perceived elements, and while working with a bat- recommendations of ISO 5349-1:2001 (2001) and ISO tery chainsaw 26 seconds with 2 percieved elements. As 5349-2:2001 (2001) standards. the recordings took place over two days, the average time In the case of two-handed work with a billhook, vibrations were measured twice at the right-hand and shares of the work elements were used in determining the left-hand grip positions. In other cases of early forest vibration exposure. A total of 25,008 observations were cleaning (one-handed work with a billhook, work with made. The daily duration of one work element was cal- culated by multiplying its average time share by 4 hours a machete and work with battery shears), vibrations were of total working time. measured at one position. Because tools in early clean- ing generate vibrations such as shocks that are extremely short in duration where it is very difficult to determine the exposure time, the following approach to vibration 2.4. Vibration level measurement level recording was applied. It was necessary to know the and vibration exposure calculation daily average number of interventions (strikes/cuts), i.e. The process of determining daily vibration exposure is the tempo of felling so that while measuring vibrations in very complex if the daily work consists of several work controlled conditions, the same number of interventions elements of different durations in which vibrations of dif- can be simulated in a certain time interval. Measurement ferent levels occur (McGeoch et al. 2005). All-day meas- of the vibration level on the tools used in the early cleaning urement of daily vibration exposure during real-time was performed three times for one minute, simulating cleaning work is extremely demanding and can lead to the tempo of felling recorded at individual sites. The UA questionable results. The reason for this is difc fi ult work - 3016 accelerometer mount was used. The measurement ing conditions, dense vegetation, questionable battery was performed at FTRC (Forest Training and Research life of the vibrometer, the need to x fi the accelerometer on Center) Zagreb on a forest gap overgrown with black the tool handle, and very likely interruptions that would locust (Robinia pseudoacacia L.) and black elderberry jeopardize the accuracy of the results. Therefore, in this (Sambucus nigra L.). The diameters of the cut trees were study, it was decided to approach the measurement of varied, from 2 to 5 cm, but suitable for the tools used. vibration in controlled conditions. After determining the When calculating the A(8) value, an exposure time of four relative shares of characteristic work elements within the hours, i.e., total daily time of working intervals, was used. daily working intervals, vibration levels in these elements Vibrations on chainsaws used in late cleaning were were measured. The instrument and equipment used in measured on both handles. Since chainsaws are two- the measurement complied with the ISO 8041:2017 handed tools, it is assumed that both hands of the worker (2017) standard, and a Brüel & Kjaer 4447 vibrometer are on the intended handles of the chainsaw during the was used in combination with a three-axial accelerom- cutting. When recording vibrations on the battery chain- eter type 4520-002 and UA 3016 and UA 3017 mounts saw, since the electric motor does not work during car- fastened with plastic ties and positioned in the immedi- rying and no vibrations are produced, the measurement Fig. 1. Vibration measurement on the tools used in early cleaning. 52 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 was performed only during the cutting. The petrol chain- average daily cutting time, recorded in time and motion saw, which uses a two-stroke engine, runs continuously study was used. The reference arm was the one with the regardless of the work element, so the measurement was highest A(8) value, and the final results were compared performed in six measuring combinations that coincide with the limits defined in the EU Directive 2002/44/EC with the perceived five work elements. (2002. While measuring the level of vibration on chain- saws, the shortness of cutting time was also a challenge. According to the ISO 5349-2:2001 (2001) standard, one 3. results and discussion measurement should not be shorter than 8 seconds. To prolong the cutting time, parts of the tree with a diam- 3.1. Time structure of working intervals eter of 8 to 20 cm, species of common hornbeam (Carpi- The time structure of working intervals is one of the key nus betulus L.) were stacked on top of each other and parts of estimating daily vibration exposure. Different fixed and cutting took 30 seconds continuously (Fig. levels of vibration occur on the left and right arm dur- 2). Chainsaws were equipped with new chains. The UA ing different work elements in a working interval, and 3017 accelerometer mount was used during the measure- in order to estimate the daily vibration exposure as accu- ment. The measurement was performed at FTRC Zagreb. rately as possible, it was necessary to obtain the duration Vibrations during cutting were recorded three times for of these elements. 30 seconds. Vibration recording on a petrol chainsaw at After a brief review of the video recordings, two work idle was also performed on three occasions of 30 seconds elements were identified during the early cleaning with each. The arithmetic mean of the three repeated measure- the two-handed billhook: one-handed striking (right ments was calculated as the final vibration total value. Daily vibration exposure A(8) is the eight-hour hand), and two-handed striking. Forest cleaning with energy equivalent of the frequency-weighted vibration a billhook was divided into two work elements due to total value, calculated by combining work element dura- the assumption that different levels of vibration occur tion data obtained in the time and motion study and vibra- depending on how many hands are on the handle of the tion total values measured under controlled conditions tool. In early cleaning, the worker had the choice to use using equation 2. only the right hand or both hands. He used both hands about three-quarters of the time (Table 3). By using both hands, the worker facilitates the work of striking ܣ ሺ ͺ ሻ ൌ ඩ ෍ܽ ൈ ܶ [2] and cutting, while one-handed work with a two-handed ௩௛ ௜ ௜ୀ ଵ billhook was tiring and required great strength. During one-handed work, the worker used his left hand to bend A(8) – daily vibration exposure; the tree to make it easier to cut and, after cutting, used a – vibration total value for i work element; hvi the same hand to remove the cut part of the tree. n – total number of work elements; T – reference working time of eight hours (28800 s); Table 3. Time share of work elements in working with a two- T – duration of i work element. handed billhook. A(8) is calculated and expressed for each hand sepa- Day 1 Day 2 Avg. Work element Avg. [%] [min] rately for tools that are handled by hands. The total expo- Two-handed striking 176.00 173.73 174.87 72.86 sure time when working with a chainsaw was set at 4 One-handed striking 64.00 66.27 65.13 27.14 hours, while when working with a battery chainsaw, the Total 240 240 240 100 Fig. 2. Vibration measurement on the chainsaws used in late cleaning. 53 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 While using battery shears and a machete, the worker in this case dictate the time structure of working inter- always used only one hand to cut, i.e. detailed time and vals. At Worksite 3, a large proportion of felled trees were motion study wasn’t required. In addition to the results above 15 cm in diameter at the position of the first cut, of the work sampling method on both the chainsaws and 20 cm at the position of the final cut in the stump. and a billhook, one of the results was the average work Therefore, the relative share of cutting in this location tempo with tools in the early cleaning (Table 4). In both was slightly higher. But despite significant differences observed locations, while working with hand tools (bill- in stand characteristics between the two observed work- hook and machete), on average, a larger number of sites, the share of cutting was approximately equal. The attempts were made to make cuts than while working most common way to carry a chainsaw was to use both with battery shears. To cut the tree with hand tools, it was hands, which was also approximately equal in both loca- not necessary to adjust the tool as with battery shears, tions. Due to the dynamic nature of cleaning work, the where the blade had to be pressed firmly against the tree worker was generally unable to place the chainsaw on at the selected location. So cutting with hand tools was the ground and rest his hands. During the field measure- more fluent because it did not require great precision. ment, this scenario did not occur. Because the worker Nevertheless, cuts with hand tools and cuts with bat- moved to another tree very soon after cutting and had tery shears were not comparable in terms of perform- to approach the next tree with a chainsaw, he couldn’t ance because they do not represent the number of trees rest it on the ground or a fallen tree, such as in delimbing cut down. With hand tools, several strikes to cut down work. Judging by this, the result that indicates the largest one tree were sometimes required, and in some cases, it relative share of carrying a saw with both hands is logical was also possible to cut down several thinner trees in one for the simple reason that in this way the worker made swing. In most cases, battery shears cut down one tree his job easier by using both hands to hold a heavy tool. with one attempt. Carrying a saw with one hand by the front handle is an individual matter of each worker which mainly depends Table 4. Average work tempo with tools in the early cleaning. on the dominance of the hand. However, a slightly higher Location Worksite 1 Worksite 2 share of using the left hand while carrying a chainsaw can Two-handed billhook 27 strikes/min — be explained by the fact that the left hand was already Machete — 23 strikes/min Battery shears 26 cuts/min 19 cuts/min on the front handle of the chainsaw when cutting, and it stayed there during the transition to carrying. Transfer- Late cleaning with a petrol chainsaw consisted of v fi e ring a chainsaw to the right hand occurs if, for various work elements: cutting, carrying with both hands, car- reasons, a slightly more extended period elapses between the felling of two trees. In this case, the worker switched rying with the right hand by the front handle, carrying with the left hand by the front handle, and carrying with hands due to fatigue caused by the static work of holding the right hand by the rear handle, noting that the chain- the chainsaw. In rare cases, the worker held the saw with saw did not turn off while carrying. Table 5 shows that his right hand by the rear handle. While holding the saw in both worksites where cleaning was performed with like this, the worker is mostly stationary and used his left chainsaws, the relative share of cutting time is slightly hand to move the cut tree canopy. more than one third, which coincides with the results of When working with a battery chainsaw, since this a German study (Huber et al. 2021) while the rest of the type of chainsaw does not produce vibrations when car- time the worker carried a powered chainsaw in multiple ried, only two work elements were determined: cutting ways with a significantly higher share of carrying with and carrying (Table 6). It should be noted that chain- both hands. The diameter of the trees and their spacing saws are two-handed tools and it is understood that both Table 5. Time share of work elements in working with a petrol chainsaw. Worksite 3 Worksite 4 Day 1 Day 2 Avg. Day 1 Day 2 Avg. Work elements Avg. [%] Avg. [%] [min] [min] Cutting 90.05 90.05 90.05 37.52 79.00 86.85 82.92 34.55 Carrying BH 78.95 81.15 80.05 33.36 68.6 80.55 74.58 31.08 Carrying RF 28.35 21.15 24.75 10.31 37.50 33.7 35.60 14.83 Carrying LF 40.20 45.85 43.03 17.93 49.60 36.10 42.85 17.85 Carrying RR 2.45 1.80 2.12 0.88 5.30 2.80 4.05 1.69 Total 240 240 240 100 240 240 240 100 1 2 3 4 both hands; right hand-front handle; left hand front-handle; right hand-rear handle. Table 6. Time share of work elements in working with a battery chainsaw. Worksite 3 Worksite 4 Day 1 Day 2 Avg. Day 1 Day 2 Avg. Work elements Avg. [%] Avg. [%] [min] [min] Cutting 111.31 128.69 109.79 45.75 89.57 93.90 91.74 38.23 Carrying 108.26 131.74 130.21 54.25 150.43 146.1 148.26 61.77 Total 240 240 240 100 240 240 240 100 54 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 hands are on the handles when cutting. While working vibration levels were the result of gentler operation with with a cordless saw, the cutting work took a little longer, battery shears where the sources of vibration are short approximately two-fifths within 8 working intervals starts of electric motor and transmission, and the interac- daily. The longer cutting time, especially at Worksite 3, tion of metal blades and wood, where there are no violent can be explained by the significantly slower chain of the shocks that would create significant vibration levels. battery chainsaw. Huber et al. (2021) found in their study that while working with a battery chainsaw, the share of Table 7. Vibration levels in tools used in the early cleaning. cutting time is one-third of the productive time. How- Work tempo [strikes Vibration total Tool Location Hand or cuts/min] value – a [m/s ] hv ever, in that study, a battery chainsaw with a signic fi antly Billhook Worksite 1 27 Right 13.54 higher chain speed was used. The chain speed depends 2 Billhook Worksite 1 27 Right 11.81 Billhook Worksite 1 27 Left 14.53 primarily on the chain pitch and the rotational speed of Battery shears Worksite 1 26 Right 1.10 the drive motor. The two-stroke petrol chainsaw engine Machete Worksite 2 23 Right 23.42 has a significantly higher maximum speed than battery Battery shears Worksite 2 19 Right 0.98 1 2 two-handed operation (left hand above right); one-handed operation (right hand). chainsaws. For this reason, a petrol chainsaw chain develops a top speed of 26 m/s, while a battery chain- When calculating the daily vibration exposure A(8) saw chain develops a top speed of 18.8 m/s. The higher in the early cleaning (Table 8), the exposure time of four relative share of cutting while working with a battery hours was used, although the effective working time chainsaw is also caused by various cutting difficulties. with the tools used is not limited by the Ordinance on Thinner trees or branches were bending in contact with Occupational Safety and Health in Forestry (1986). In a battery chainsaw chain that did not have enough speed practice, workers rarely work longer than four effective to make a quick cut. Furthermore, a battery chainsaw hours in early cleaning due to unbearable heat and dif- chain is extremely thin, which resulted in frequent chain ficult working conditions. On the billhook, which is the slipping during the first cut if the guide was not laid cor- only two-handed tool in early cleaning, it has been estab- rectly on the tree, i.e. if it was slanted to the side. lished that the right hand is the reference, so the results will be observed for the right hand. The higher recorded daily exposure on the right hand is logical because that 3.2. Vibration levels and daily vibration hand was always in contact with the tool, regardless of exposure one-handed or two-handed operation, while the left hand While cleaning with a billhook, vibration levels were is not in contact with the tool in one-handed operation. higher during two-handed operation. While using both Daily exposure to vibrations on the right (and left) hand hands, the speed of the swing, and thus the force of the while working with a billhook significantly exceeded impact on the wood, was higher, which caused higher the limit value of 5 m/s , and according to EU Directive recorded vibrations (Table 7). For this reason, one- 2002/44/EC (2002) such work should not be continued. handed work with a two-handed billhook creates sig- At the level of vibration occurring on the right hand in the nificantly less vibration than work with a one-handed two-handed operation, it took 16 minutes of work (con- billhook that swings slightly faster, which is supported by tinuous striking) to reach an exposure of 2.5 m/s or an a previous study (Bačić et al. 2020) where a vibration level action value, and 65 minutes of work to reach a limit value of 19.34 m/s was recorded on a one-handed billhook. of 5 m/s . On the right hand in the one-handed opera- The highest level of vibration was recorded while clean- tion, it took 22 minutes to reach the action value, and 86 ing with a machete, which was expected. Namely, the minutes to the limit value. Daily exposure to vibrations machete, unlike a billhook, did not have a wooden handle was highest while working with a machete, and the result that separates the metal blade, that is the source of the obtained was similar to the result from the previous study vibration, from the hand and reduced the transmission of (Bačić et al. 2020) on a one-handed billhook of 13.7 m/s . vibration to the hands of workers. The role of the handle The calculated value was extremely high, and it took in vibration transmission is significant (Beckley 2019). only 5 minutes of work to reach the action value, while The metal blade of the machete effectively conducted the the limit value took 22 minutes of work. While working vibrations created by striking the wood to the handle of with battery shears, for both observed locations, a very the machete (worker’s hand) which consisted of two mir- low daily exposure to vibration was calculated, and it ror pieces of wood attached to the metal part. The small took over 24 hours to reach the action and limit values. dimensions of the machete handle do not have a great It should be kept in mind that the shock (vibration) while ability to dampen the vibrations created (Kocjančić working with hand tools is of very short duration and that 2018). The level of vibration recorded while working with the frequency characteristics of this type of vibration were battery shears is extremely low. There is a minimal differ- not investigated in this paper. This study relies on fre- ence due to the two different work tempos at which the quency weighting algorithms that are incorporated into vibrations were recorded. Slightly higher vibration levels the used instrument (vibrometer) and thus find these were recorded at a faster tempo with battery shears. Low results relevant. 55 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 2 2 Table 8. Daily vibration exposure in tools used in the early declared 4.6 m/s on the front handle and 3.9 m/s on the cleaning. rear handle (MSA 200 C–B 2022), but with an approxi- Tool Billhook Machete Battery shears mately similar ratio between the front and rear handle. Location Worksite 1 Worksite 2 Worksite 1 Worksite 2 2 2 2 2 Right hand A(8) 9.3 m/s 16.6 m/s 0.8 m/s 0.7 m/s Left hand A(8) 8.8 m/s — — — Table 9. Vibration levels in chainsaws used in the late cleaning. Work element Hand Handle The petrol chainsaw generated vibrations in all work elements, while the battery chainsaw vibrated only when Chainsaw type cutting. Vibration levels are presented according to the measurement combinations (Table 9). While cutting 1 × × × 4.05 with a petrol chainsaw, higher levels of vibration were 2 × × × 3.62 recorded on the front handle which is not in line with 3 × × × 3.57 the results of Goglia et al. (2012) where higher levels of Petrol chainsaw 4 × × × 5.62 × × × 5.69 vibration in cutting are recorded on the rear handle (Stihl 5 × × × 5.69 MS 260) and the results of a German study (Huber et al. 6 × × × 6.30 1 × × × 5.15 2021) where a Stihl MS 201 C chainsaw is used. When Battery chainsaw 2 × × × 4.29 carrying a chainsaw with both hands, a higher level of 1 2 carrying with one hand; carrying with both hands. vibration was recorded on the rear handle, as noted by Goglia et al. (2012) but with higher values. Furthermore, According to the results of daily exposure to vibration the results obtained also coincide with the above study while working with a petrol chainsaw (Table 10), higher while carrying a chainsaw with one hand (left and right) exposure was recorded on the right hand, while the left by the front handle and the right hand by the rear han- hand was more exposed on the battery chainsaw, and dle where the highest level of vibration was recorded. they are considered a reference. In both observed loca- Compared to the declared vibration levels of 3.5 m/s tions, lower exposure to vibrations was observed while on both handles (MSA 200 C-B 2022), higher vibration working with a battery chainsaw as in previous studies levels were recorded in all measuring combinations for (Colantoni et al. 2016; Neri et al. 2018; Poje et al. 2018). petrol chainsaws. Vibration exposure while working with a petrol chainsaw An interesting result is that slightly higher levels of at both worksites exceeded the exposure action value of vibration while cutting were recorded on a battery chain- 2.5 m/s , while when working with a battery chainsaw saw in contrast to the Slovenian study (Poje et al. 2018) at Worksite 3, the estimated exposure was exactly at the and the German study (Huber et al. 2021). In these stud- exposure action value. It took 1 hour and 53 minutes to ies, higher vibration levels are also recorded on the front reach the exposure action value with a battery chainsaw, handle of the battery chainsaw. The Makita DUC302Z while it took 7 hours and 32 minutes to reach the expo- battery chainsaw is tested in a Slovenian study and the sure limit value. Differences in daily vibration exposure Stihl MSA 220 C in a German study. A probable reason for (on the same chainsaw) between the two worksites are the increase in recorded vibration levels, apart from the minimal and stemmed from differences in the relative different types of chainsaws tested, is the fact that the bat- time shares of work elements. tery chainsaw used in this study had a lower mass than the mentioned chainsaws causing higher vibration levels at Table 10. Daily vibration exposure in chainsaws used in the work (Malchaire 2020). The observed chainsaw had less late cleaning. mass because it did not use a small battery that is stored Chainsaw type Petrol chainsaw Battery chainsaw in the housing, which increases its total mass, but instead Location Worksite 3 Worksite 4 Worksite 3 Worksite 4 2 2 2 2 Left hand A(8) 2.8 m/s 2.8 m/s 2.5 m/s 2.3 m/s used a backpack battery. It should be borne in mind that 2 2 2 2 Right hand A(8) 3.1 m/s 3.2 m/s 2.0 m/s 1.9 m/s different vibration recording methods and different types of chainsaws can also give different results of vibration level measurements. In this research, the methods and 4. Conclusion conditions of vibration recording were designed to rep- resent the actual e fi ld conditions as faithfully as possible, Vibration levels and daily vibration exposure while clean- while meeting the applicable measurement standards. ing with battery shears are many times lower compared Furthermore, the battery chainsaw used in this study was to cleaning with a two-handed billhook and machete. The not equipped with a conventional anti-vibration system work tempo with all the observed tools in the early clean- which is common for battery chainsaws that do not pro- ing is similar, but the technique and mode of operation duce high levels of vibration due to the circular motion of of the tool are quite different. Cutting a tree using battery their drive motor. By the interaction of chain and wood shears was u fl ent, without jerks and sudden movements, which is a heterogeneous material, certain deviations in while cutting with hand tools was quite the opposite, the measured vibration levels occur. The recorded vibra- moreover, the greater the force of impact - the better the tion levels on the battery chainsaw were higher than the effect of cutting. High forces during work and sudden Measuring combination Cutting Carrying Left Right Front Rear Vibration total value –a [m/s ] hv M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 stops of tools when striking wood had caused very high Bačić, M., Šušnjar, M., Zečić, Ž., Koren, S., Kolarić, recorded vibration levels in hand tools, and consequently M., Pandur, Z., 2020: Daily vibration exposure in high daily exposure. forestry: the difference between manual and motor- Although the recorded vibration levels on the used manual cleaning methods. Sigurnost, 62:265–274. battery chainsaw were higher than on the petrol chain- Barnes, R., Longley, E. O., Smith, A. R. B., Allen, J. G., saw, the daily exposure was lower. The complete absence 1969: Vibration disease. Medical Journal of Australia, of vibrations caused by the rotation of the drive motor in 1:901–905. the work element of carrying the battery chainsaw had Beckley, B., 2019: One Moving Part: The Forest Service an extremely large impact on daily exposure. Due to the Ax Manual. Missoula, MT, p. 45–49. slower chain, the duration of the cutting with a battery Bower, A., Qi, Y., Bazilevs, Y., 2022: E40 Dynamics and chainsaw was somewhat longer, and it can be concluded Vibrations – lectures. Brown University, School of that using newer models of battery chainsaws, with Engineering, Providence, USA. higher chain speed, would shorten the total duration of Brammer, A. J., Pyykkö, I., 1987: Vibration-induced the cutting at the expense of increasing the duration of neuropathy: Detection by nerve conduction measure- carrying, which would additionally lower the daily vibra- ments. Work, Environment & Health, 13:317–322. tion exposure. Colantoni, A., Mazzocchi, F., Cossio, F., Cecchini, M., The recorded vibration levels, as well as the daily Bedini, R., Monarca, D., 2016: Comparisons between exposure, were many times higher in the early cleaning battery chainsaws and internal combustion engine with a billhook and machete than in the late cleaning chainsaws: performance and safety. Contemporary with a chainsaw. In operational forestry, workers with Engineering Sciences, 9:1315–1337. reduced working ability are excluded from working with de Oliveira, F. M., Lopes, E. S., Rodrigues, C. K., 2014: a chainsaw due to a diagnosed white fingers disease and Evaluation of the physical workload and biomechani- the fact that the chainsaws are vibrating tools. Some of cal of workers at manual and semi-mechanized mow- these workers are transferred to silvicultural work with ing. Cerne, 20:419–425. hand tools such as billhook and machete which are not Forouharmajd, F., Yadegari, M., Ahmadvand, M., considered vibrating tools. From the above mentioned, it Forouharmajd, F., Pourabdian, S., 2017: Hand-arm can be concluded that a detailed revision in the classic fi a - Vibration Effects on Performance, Tactile Acuity, and tion of tools is needed, considering their ability to produce Temperature of Hand. Journal of Medical Signals and and transmit harmful vibrations to the operator and that Sensors, 7:252–260. using the current classic fi ation can be unfavorable for the Goglia, V., Žgela, J., Suchomel, J., Đukić, I., 2001: Expo- worker and his health. sure to hand-arm transmitted vibration at forest nurs- ery and thinning. Human Resources Management and Ergonomics, 5:45–55. Goglia, V., Žgela, J., Suchomel, J., Đukić, I., 2012: The Acknowledgments effectiveness of forest pre-commercial thinning in The research was cofunded by the Hrvatske šume Ltd. within the context of Directive 2002/44/EC. Šumarski list, the Project «Ergonomska pogodnost i ekonomska isplativost  136:471–478. primjene akumulatorske motorne pile i akumulatorskih škara Huber, M., Hoffmann, S., Brieger, F., Hartsch, F., Jaeger, u radovima njege i čišćenja jednodobnih sastojina», project  D., Sauter, U. H., 2021: Vibration and Noise Expo- number DIR-01-17-3432/02. sure during Pre-Commercial Thinning Operations: What Are the Ergonomic Benefits of the Latest Gen- eration Professional-Grade Battery-Powered Chain- references saws? Forests, 1: 1120. Anić, I., 2007: Uzgajanje šuma I – internal script. Fac- Jobidon, R., Roy, V., Cyr, G., 2003: Net effect of compet- ulty of Forestry and Wood Technology, University of ing vegetation on selected environmental conditions Zagreb, p. 1–97. and performance of four spruce seedling stock sizes Araki, S., Honma, T., Aoyama, K., 1976: Peripheral after eight years in Quebec (Canada). Annals of For- nerve conduction velocities in chainsaw operators. est Science, 60:691–699. Japanese Journal of Industrial Health, 18:516–520. Kocjančić, L., 2018: Izbira sekaške sekire glede na jakost Axelsson, S-A., 1968: Analysis of Vibration in Power tresenja in obremenitve ledvenega dela. B. Sc. thesis, Saws. Studia Forestalia Suecica, 59:1–47. Univerza v Ljubljani, Biotehniška fakulteta, Oddelek Bačić, M., Landekić, M., Šušnjar, M., Šporčić, M., Pan- za gozdarstvo in obnovljive gozdne vire. dur, Z., 2019: Movement analysis of a worker in the Landekić, M., Bačić, M., Pandur, Z., Šušnjar, M., 2020: forest cleaning activities. In: Proceedings of the 52nd Vibration Levels of Used Chainsaws. Forests, 11:1– International Symposium on Forestry Mechaniza- tion: “Exceeding the Vision: Forest Mechanisation of the Future”, Sopron, 6–10 October 2019. 57 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 Malchaire, J., 2020: Vibrations Mains-Bras: Serie Strat- Tambić Bukovac, L., Šenjug Perica, M., 2017: Raynau- egie Sobane–Gestion des Risques Professionnels. dov sindrom. Paediatria Croatica, 61:38–42. Brochure, Service public fédéral Emploi, Travail et Taylor, W., Pearson, J., Kell, R. L., Keighley, G. D., 1971: Concertation sociale, Brussels, p. 1–70. Vibration syndrome in Forestry Commission chain Malinowska-Borowska, J., Harazin, B., Zieliński, G., saw operators. British Journal of Industrial Medicine, 2012: Measuring coupling forces woodcutters exert 28:83–89. on saws in real working conditions. International Thompson, D. G., Pitt, D. G., 2003: A review of Canadian Journal of Occupational Safety and Ergonomics, forest vegetation management research and practice. 18:77–83. Annals of Forest Science, 60:559–572. Malinowska-Borowska, J., Harazin, B., Zieliński, G., Other sources 2011: The influence of wood hardness and logging Directive 2002/44/EC, 2002: The mimimum health operation on coupling forces exerted by lumberjacks requirement regarding the exposure of workers to the during wood harvesting. International Journal of risks arising from physical agents (vibration). Ofc fi ial Industrial Ergonomics, 41:546–550. Journal of the European Communities,177:13–19. Malinowska-Borowska, J., Zieliński, G., 2013: Coupling ISO 11681-1:2011. Machinery for forestry – Portable forces exerted on chain saws by inexperienced tree chain-saw safety requirements and testing – Part 1: fellers. International Journal of Industrial Ergonom- Chain-saws for forest service. International Standard ics, 43:283–287. organization, Geneva, p. 1–22. McGeoch, K. L., Lawson, I. J., Burke, F., Proud, G., ISO 5349-1:2001. Mechanical vibration – Measurement Miles, J., 2005: Diagnostic criteria and staging of and evaluation of human exposure to hand transmit- hand-arm vibration syndrome in the United King- ted vibration. Part 1: General requirements. Interna- dom. Industrial Health, 43:527–534. tional Standard organization, Geneva, p. 1–26. Miura, T., Kimura, K., Tominaga, Y., Kimotsuki, K., ISO 5349-2:2001. Mechanical vibration – Measurement 1965: On the Raynaud’s Phenomenon of Occupa- and evaluation of human exposure to hand-transmit- tional Origin due to Vibrating Tools–ts Incidence in ted vibration – Part 2: Practical guidance for meas- Japan. Journal of Science of Labour, 42:725–747. urement at the workplace. International Standard Neri, F., Laschi, A., Foderi, C., Fabiano, F., Bertuzzi, organization, Geneva, p. 1–39. Lucia., Marchi, E., 2018: Determining noise and ISO 8041-1:2017. Human response to vibration – Meas- vibration exposure in conifer cross-cutting opera- uring instrumentation – Part 1: General purpose tions by using li-ion batteries and electric chainsaws. vibration meters. International Standard organiza- Forests, 9:1–13. tion, Geneva, p. 1–106. Poje, A., Potočnik, I., Mihelič, M., 2018: Comparison of MS 261. Available online: https://unikomerc-uvoz.hr/ Electric and Petrol Chainsaws in Terms of Efficiency ms-261 (accessed on 19 April 2022). and Safety When Used in Young Spruce Stands in MSA 200 C-B. Available online: https://unikomerc-uvoz. Small-Scale Private Forests. Small-Scale Forestry, hr/msa-200-c-bq-aku-pila (accessed on 19 April 17:1–12. 2022). Seppäläinen, A. M., 1972: Peripheral neuropathy in Ordinance on Occupational Safety and Health in For- forest workers. A field study. Work, Environment & estry. Official Gazette, 10/86, 1986, p. 1–18. Health, 9:106–111. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Forestry Journal de Gruyter

Vibration levels and daily vibration exposure while using different tools in a forest cleaning

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de Gruyter
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© 2023 Marin Bačić et al., published by Sciendo
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0323-1046
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2454-0358
DOI
10.2478/forj-2022-0015
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Abstract

Forest cleaning, being an operation that requires investment, but the return on investment is due for the next genera- tions, utilizes tools and methods that mostly haven’t been humanized. Harmful vibration is still present in today’s forestry operations, and new tools provide possible reduction of exposure to vibrations. Petrol chainsaw and battery chainsaw (late cleaning) and billhook, machete, and battery shears (early cleaning) were used and observed in this study. Vibration levels were measured and assessed using validated Brüel & Kjær 4447 vibrometer which complies with the ISO 8041:2017 standard. The measurement was performed according to the recommendations of ISO 5349-1:2001 and ISO 5349-2:2001 standards. Vibration exposure was assesed using work sampling method on the obtained video recordings in order to calculate relative shares of different work elements. Results show that hand tools (machete and billhook) are causing the highest vibration levels, while battery shears cause the lowest. Bat- tery chainsaw causes higher vibration levels while cutting, but lower daily vibration exposure than petrol chainsaw. A detailed revision in the classification of tools is needed, considering their ability to produce and transmit harmful vibrations to the operator. Using the current classification, the daily exposure to vibration of workers in early forest cleaning is high above legislative values. Key words: forest cleaning; hand tools; battery tools; vibration levels; vibration exposure Editor: Miroslav Hájek eters that are very important for the future structure of 1. Introduction the stand (Anić 2007). Forest cleaning is one of the work processes of forest Forest cleaning requires n fi ancial investment, and the tending that is carried out in the developmental stages results of work in the form of a quality stand will only of saplings and young trees, this work process removes be exploited by future generations. Therefore, since this from the stand everything that is considered poor quality is a silvicultural procedure that does not bring direct and superu fl ous for the stand future development such as financial income, the improvement of these operations cancer, bent, forked, broken, branched, damaged trees, was not a priority, and the methods and tools used in trees with abnormally developed canopy, trees with these works are outdated (Bačić et al. 2019). Further- broken, damaged or deformed top, shoots, overgrowth, more, some studies state that, unlike wood harvesting trees deformed in the various shapes, etc., therefore for- operations which are highly mechanized and use efc fi ient est cleaning has the character of negative selection (Anić mechanization and equipment, silvicultural operations, 2007). especially forest cleaning, are performed by manual or Forest cleaning is done in the early years after felling motor-manual methods involving a high proportion of or artic fi ial rejuvenation to eliminate competitive vegeta - manual labor (de Oliveira et al. 2014). In Croatian for- tion that outgrows the young or planted trees (Thompson estry, sickles, machetes, and billhooks are used in early & Pitt 2003). The rapid growth of stronger breeding spe- forest cleaning, and so-called “silvicultural” chainsaws cies after harvest requires an early cleaning procedure are used in late forest cleaning where hand tools are not in artificially or naturally rejuvenated stands to ensure an apropriate tool. optimal sapling growth (Jobidon et al. 2003; Thompson Mechanical forest cleaning can generally be divided & Pitt 2003). Cleaning regulates the stand shape by inu fl - into two parts according to the diameter of the trees and encing the type, shape, and ratio of the mixture, param- the tools used: manual cleaning (early forest cleaning) *Corresponding author. Zdravko Pandur, e-mail: zpandur@sumfak.unizg.hr © 2022 Authors. This is an open access article under the CC BY 4.0 license. M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 and motor-manual cleaning (late forest cleaning). Dur- measures intended to reduce to minimum exposure to ing manual cleaning, the worker holds a one-handed bill- mechanical vibration. Should workers be exposed above hook or machete in one hand, and with the other hand the exposure limit value, the employer shall take immedi- bends a tree that will be cut down for easier cutting. Two- ate action to reduce exposure below the exposure limit handed billhooks are more common due to the longer value. Due to the aforementioned harmful effects of range and stronger cutting force. In that case, the worker vibrations, the working hours of workers on chainsaws can use a two-handed billhook either with one or both are regulated in the Republic of Croatia, more precisely hands. Sometimes more swings are needed to perform according to the Ordinance on Occupational Safety and in order to cut. After cutting, the worker lowers the cut Health in Forestry (1986), a worker may not work effec- tree from the canopy zone and lays it on the ground. The tively with a chainsaw for more than four hours a day. distribution of felled trees is not uniform, trees located on There are many inu fl encing factors on which the level, the edge of the silvicultural trails are placed on those trails transmission, and exposure to vibration depend. Accord- however, felled trees within the cleaned area (bounded ing to ISO 5349-1:2001 (2001), the risk of consequences by silvicultural trails and haulage tracks) are distributed depends on the level of vibration, duration of exposure, according to the further needs of workers. Sometimes and frequency. Lower saw mass causes higher measured most of the felled trees are disposed of in a forest gap to vibration levels (Malchaire 2020). Increasing the stiff- give the worker more freedom of movement and access ness of the spring increases the natural frequency of the to other trees. system, while increasing the mass reduces the natural In the operations of cleaning even-aged stands in frequency of the system (Bower et al. 2022). The grip which hand tools can no longer be used, a professional strength of a chainsaw handle, which affects the trans- chainsaw of smaller dimensions and smaller mass is mission of vibrations to the hand-arm system, depends mainly used. In such stands, some trees that can be char- on the worker’s work experience, work operation, and acterized as overgrown reach over 20 cm in diameter on hardwood. Taking this into account, the grip is stronger the stump, so the use of a chainsaw in such cleaning work in less-experienced workers, in felling and sawing, and in is necessary. Usually, the r fi st cut is at an angle and at the the wood of higher hardness (Malinowska-Borowska et height of the worker’s shoulder, so that the upper part of al. 2011; Malinowska-Borowska et al. 2012; Malinowska- the tree can “slip” from the lower part. Then, if necessary, Borowska & Zieliński 2013). According to ISO 11681- the worker makes one or two more cuts in the same way 1:2011 (2011), the main factors affecting the level of until the canopy is lowered to the ground. The worker vibration in chainsaws are mainly dynamic forces in the then makes another horizontal cut in the stump of the motor, cutting mode, unbalanced moving parts, impacts remaining part of the tree. in gears, bearings, and other mechanisms, and also the Since the introduction of chainsaws in forestry, interaction between worker, chainsaw, and wood being numerous studies have reported signs and symptoms cut. Although chainsaw parts degrade with years of use, associated with vibration exposure while working with Landekić et al. (2020) concluded that age, i.e. years of use a chainsaw in forestry (Miura et al. 1965; Axelsson 1968; does not affect the level of vibration in used petrol chain- Barnes et al. 1969; Taylor et al. 1971). There are many saws. Studies (Colantoni et al. 2016; Neri et al. 2018; Poje synonyms for diseases caused by vibrations, the most et al. 2018; Huber et al. 2021) indicate signic fi antly lower common is the so-called “White finger disease” or sec - noise and vibration levels in battery chainsaws compared ondary Raynaud’s syndrome (Tambić Bukovac & Šenjug to petrol chainsaws of the same class. Goglia et al. (2011, Perica 2017). Numbness in the hands and arms, tingling 2012) in their study of the work with chainsaw silvicul- in the fingers, and deterioration of tactile perception tural operations record the daily exposure of workers to have been detected in workers who have been exposed vibrations above the warning limit and in some cases 2 2 to hand-arm vibrations (Seppäläinen 1972; Araki et al. 4.3 m/s and 4.5 m/s . 1976; Brammer & Pyykkö 1987). Hand-arm vibrations In addition to chainsaws that are used in motor-man- cause disorders in the blood supply to the fingers and in ual cleaning, and are a well-known and researched source the peripheral nerves of the hands and arms (Neri et al. of vibration, tools used in manual cleaning methods 2018). Workers exposed daily to excessive vibrations (billhook and machete) can also have a negative impact transmitted to the hand-arm system could suffer, on on worker health. The level of vibration is significantly long term, blood flow disorders in fingers and disorders affected by the type of handle with which the tool is of neurological functions and movements of hand and equipped. Hardwood handles (ash, hickory, and oak) arm (Forouharmajd et al. 2017). with a straight wire that is parallel to the tool blade trans- The daily vibration exposure values for the hand-arm mit less vibration to the hands of workers than fiberglass system specie fi d by EU Directive 2002/44/EC (2002) are and other synthetic handles (Beckley 2019). Kocjančić prescribed as a daily exposure action value of 2.5 m/s , (2018) states the length of the handle and the material and a daily exposure limit value of 5 m/s . Once the expo- as the main factors in the transmission of vibrations on sure action value is exceeded, the employer shall establish chopping axes. As an alternative to the manual method and implement a program of technical and organizational of forest cleaning using hand tools, intensive research on 50 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 the use of battery shears is being conducted in Croatian than one way were filmed using a small hand-held action forestry (Bačić et al. 2019). Bačić et al. (2020) report camera in order to perform time and motion study. This significantly higher levels of daily exposure to vibration resulted in a total of 40 hours of video material. A total of A(8) when working with a one-handed billhook than 8 hours of working intervals using a two-handed billhook, when working with a chainsaw. 16 hours of working intervals using a battery chainsaw, Therefore, the aim of this paper is to evaluate and and 16 hours of working intervals using a petrol chain- compare new battery tools and conventional tools used saw were recorded. Machete and battery shears were in forest cleaning from an vibration exposure standpoint. always used one-handed and those working intervals were not subjected to video recording. However, in all the working intervals in early forest cleaning, a number of swings/cuts was obtained using a simple mechanical 2. Materials and methods click counter. That was done in order to simulate the same 2.1. Observed tools and workers work tempo when measuring vibration levels generated by those tools. In the early cleaning, Stihl ASA 85 battery shears with Time and motion study was required in order to AP 300 battery, a two-handed billhook, and a machete accurately assess daily vibration exposure in the tools were used. While in late cleaning Stihl MS 261 petrol that are used in more than one way. Huber et al. (2021) chainsaw and Stihl MSA 200 battery chainsaw with AR in their study estimate that cutting work while using pet- 3000 backpack battery were used (Table 1). rol chainsaw and battery chainsaw in cleaning accounts Four male forest workers on four worksites were for one-third of total productive time. A work sampling involved in the measurements ranging from 35 to 59 method was used on the obtained video recordings in years. order to calculate relative shares of different work ele- ments within 4 hours of working intervals daily. During a short review and with experience from the previous 2.2. Worksites research (Bačić et al. 2020), an approximate percent- The first two worksites represented early forest clean - age of perceived working activities within one working ing conditions, and the second two worksites represented interval was determined, and after that, the review of the late forest cleaning (Table 2). entire recordings was started using the method of work sampling. For a 95% confidence interval, the required number of observations and recordings of work elements in one working day was calculated using equation 1. 2.3. Work dynamics, time and motion study ͲͲ͸ͳ ൈሺ ͳെ ݌ሻ ܰ ൌ On all worksites, workers were instructed to work with [1] respect to the defined work dynamic which was 30 min N – required number of observations; of work followed by 15 min of rest, with one 30 min rest p – percentage share of the least represented work element after 4 working intervals. Workers would not change the (calculated by previous short video review). tool in one working day which lasted 6 hours and 15 min- The observation interval was calculated from the ratio utes, of which 4 hours were working intervals. Working of the total duration of the video recordings in seconds intervals with tools that could be used or held in more Table 1. Main tool features. Tool Features ASA 85 battery shears Mass of 0.98 kg, maximum cutting diameter 45 mm, declared vibration level of 2,5 m/s Two-handed billhook Length of 125 cm, mass of 1.43 kg, beechwood handle Machete Length of 61 cm, mass of 0.4 kg MS 261 petrol chainsaw Mass of 5.2 kg, bar length of 37 cm, Rapid Super chain, declared vibration level of 3,5 m/s on both of the handles 2 2 MSA 200 battery chainsaw Mass of 3.3 kg, bar length of 30 cm, Picco Micro 3 chain, declared vibration level of 4,6 m/s on the front and 3.9 m/s on the rear handle Table 2. Worksite description. Location Description A young stand of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea Matt.) with admixtures of sycamore maple (Acer pseudoplatanus Worksite 1 L.) and european ash (Fraxinus excelsior L.) in the developmental stage of young trees. The terrain was of southern exposure, with a slope of 9–14%. A young stand of pedunculate oak (Quercus robur L.), common beech (Fagus sylvatica L.), and common hornbeam (Carpinus betulus L.) in the develo- Worksite 2 pmental stage of young trees with developed weed vegetation on the entire surface. The terrain was without slope. Young stand of common beech (Fagus sylvatica L.). Other types of trees include common hornbeam (Carpinus betulus L.), common birch (Betula pendula Roth), and sycamore maple (Acer pseudoplatanus L.). The stand was in the developmental stage of young trees. The soil was covered with Worksite 3 leaves, without bushes and ground growth. The presence of common birch of larger breast diameters was pronounced. The terrain was of southwestern exposure, with a slope of 8–12%. A young mixed stand of pedunculate oak (Quercus robur L.), european ash (Fraxinus excelsior L.), field maple ( Acer campestre L.), and field elm (Ulmus minor Mill.) mixed with common hornbeam (Carpinus betulus L.), white willow (Salix alba L.), and fruit trees. The developmental stage was of Worksite 4 young trees. The stand was medium to densely overgrown, with a heterogeneous mixture-quality ratio. The soil was overgrown with ground growth and hawthorn (Crataegus spp.) and blackthorn (Prunus spinosa L.) bushes. The terrain was without slope. 51 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 and the required number of observations for the least rep- ate vicinity of the operator’s hand (Fig. 1). Simulation resented work element. For videos of early cleaning (only of work in controlled conditions with one-handed tools with a two-handed billhook) the observation interval was was performed with the right hand as the dominant. The 8 seconds with 2 perceived elements, while for videos of vibrometer was calibrated by an accredited company, later cleaning with a petrol chainsaw it was 3 seconds and the measurement was performed according to the with 5 perceived elements, and while working with a bat- recommendations of ISO 5349-1:2001 (2001) and ISO tery chainsaw 26 seconds with 2 percieved elements. As 5349-2:2001 (2001) standards. the recordings took place over two days, the average time In the case of two-handed work with a billhook, vibrations were measured twice at the right-hand and shares of the work elements were used in determining the left-hand grip positions. In other cases of early forest vibration exposure. A total of 25,008 observations were cleaning (one-handed work with a billhook, work with made. The daily duration of one work element was cal- culated by multiplying its average time share by 4 hours a machete and work with battery shears), vibrations were of total working time. measured at one position. Because tools in early clean- ing generate vibrations such as shocks that are extremely short in duration where it is very difficult to determine the exposure time, the following approach to vibration 2.4. Vibration level measurement level recording was applied. It was necessary to know the and vibration exposure calculation daily average number of interventions (strikes/cuts), i.e. The process of determining daily vibration exposure is the tempo of felling so that while measuring vibrations in very complex if the daily work consists of several work controlled conditions, the same number of interventions elements of different durations in which vibrations of dif- can be simulated in a certain time interval. Measurement ferent levels occur (McGeoch et al. 2005). All-day meas- of the vibration level on the tools used in the early cleaning urement of daily vibration exposure during real-time was performed three times for one minute, simulating cleaning work is extremely demanding and can lead to the tempo of felling recorded at individual sites. The UA questionable results. The reason for this is difc fi ult work - 3016 accelerometer mount was used. The measurement ing conditions, dense vegetation, questionable battery was performed at FTRC (Forest Training and Research life of the vibrometer, the need to x fi the accelerometer on Center) Zagreb on a forest gap overgrown with black the tool handle, and very likely interruptions that would locust (Robinia pseudoacacia L.) and black elderberry jeopardize the accuracy of the results. Therefore, in this (Sambucus nigra L.). The diameters of the cut trees were study, it was decided to approach the measurement of varied, from 2 to 5 cm, but suitable for the tools used. vibration in controlled conditions. After determining the When calculating the A(8) value, an exposure time of four relative shares of characteristic work elements within the hours, i.e., total daily time of working intervals, was used. daily working intervals, vibration levels in these elements Vibrations on chainsaws used in late cleaning were were measured. The instrument and equipment used in measured on both handles. Since chainsaws are two- the measurement complied with the ISO 8041:2017 handed tools, it is assumed that both hands of the worker (2017) standard, and a Brüel & Kjaer 4447 vibrometer are on the intended handles of the chainsaw during the was used in combination with a three-axial accelerom- cutting. When recording vibrations on the battery chain- eter type 4520-002 and UA 3016 and UA 3017 mounts saw, since the electric motor does not work during car- fastened with plastic ties and positioned in the immedi- rying and no vibrations are produced, the measurement Fig. 1. Vibration measurement on the tools used in early cleaning. 52 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 was performed only during the cutting. The petrol chain- average daily cutting time, recorded in time and motion saw, which uses a two-stroke engine, runs continuously study was used. The reference arm was the one with the regardless of the work element, so the measurement was highest A(8) value, and the final results were compared performed in six measuring combinations that coincide with the limits defined in the EU Directive 2002/44/EC with the perceived five work elements. (2002. While measuring the level of vibration on chain- saws, the shortness of cutting time was also a challenge. According to the ISO 5349-2:2001 (2001) standard, one 3. results and discussion measurement should not be shorter than 8 seconds. To prolong the cutting time, parts of the tree with a diam- 3.1. Time structure of working intervals eter of 8 to 20 cm, species of common hornbeam (Carpi- The time structure of working intervals is one of the key nus betulus L.) were stacked on top of each other and parts of estimating daily vibration exposure. Different fixed and cutting took 30 seconds continuously (Fig. levels of vibration occur on the left and right arm dur- 2). Chainsaws were equipped with new chains. The UA ing different work elements in a working interval, and 3017 accelerometer mount was used during the measure- in order to estimate the daily vibration exposure as accu- ment. The measurement was performed at FTRC Zagreb. rately as possible, it was necessary to obtain the duration Vibrations during cutting were recorded three times for of these elements. 30 seconds. Vibration recording on a petrol chainsaw at After a brief review of the video recordings, two work idle was also performed on three occasions of 30 seconds elements were identified during the early cleaning with each. The arithmetic mean of the three repeated measure- the two-handed billhook: one-handed striking (right ments was calculated as the final vibration total value. Daily vibration exposure A(8) is the eight-hour hand), and two-handed striking. Forest cleaning with energy equivalent of the frequency-weighted vibration a billhook was divided into two work elements due to total value, calculated by combining work element dura- the assumption that different levels of vibration occur tion data obtained in the time and motion study and vibra- depending on how many hands are on the handle of the tion total values measured under controlled conditions tool. In early cleaning, the worker had the choice to use using equation 2. only the right hand or both hands. He used both hands about three-quarters of the time (Table 3). By using both hands, the worker facilitates the work of striking ܣ ሺ ͺ ሻ ൌ ඩ ෍ܽ ൈ ܶ [2] and cutting, while one-handed work with a two-handed ௩௛ ௜ ௜ୀ ଵ billhook was tiring and required great strength. During one-handed work, the worker used his left hand to bend A(8) – daily vibration exposure; the tree to make it easier to cut and, after cutting, used a – vibration total value for i work element; hvi the same hand to remove the cut part of the tree. n – total number of work elements; T – reference working time of eight hours (28800 s); Table 3. Time share of work elements in working with a two- T – duration of i work element. handed billhook. A(8) is calculated and expressed for each hand sepa- Day 1 Day 2 Avg. Work element Avg. [%] [min] rately for tools that are handled by hands. The total expo- Two-handed striking 176.00 173.73 174.87 72.86 sure time when working with a chainsaw was set at 4 One-handed striking 64.00 66.27 65.13 27.14 hours, while when working with a battery chainsaw, the Total 240 240 240 100 Fig. 2. Vibration measurement on the chainsaws used in late cleaning. 53 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 While using battery shears and a machete, the worker in this case dictate the time structure of working inter- always used only one hand to cut, i.e. detailed time and vals. At Worksite 3, a large proportion of felled trees were motion study wasn’t required. In addition to the results above 15 cm in diameter at the position of the first cut, of the work sampling method on both the chainsaws and 20 cm at the position of the final cut in the stump. and a billhook, one of the results was the average work Therefore, the relative share of cutting in this location tempo with tools in the early cleaning (Table 4). In both was slightly higher. But despite significant differences observed locations, while working with hand tools (bill- in stand characteristics between the two observed work- hook and machete), on average, a larger number of sites, the share of cutting was approximately equal. The attempts were made to make cuts than while working most common way to carry a chainsaw was to use both with battery shears. To cut the tree with hand tools, it was hands, which was also approximately equal in both loca- not necessary to adjust the tool as with battery shears, tions. Due to the dynamic nature of cleaning work, the where the blade had to be pressed firmly against the tree worker was generally unable to place the chainsaw on at the selected location. So cutting with hand tools was the ground and rest his hands. During the field measure- more fluent because it did not require great precision. ment, this scenario did not occur. Because the worker Nevertheless, cuts with hand tools and cuts with bat- moved to another tree very soon after cutting and had tery shears were not comparable in terms of perform- to approach the next tree with a chainsaw, he couldn’t ance because they do not represent the number of trees rest it on the ground or a fallen tree, such as in delimbing cut down. With hand tools, several strikes to cut down work. Judging by this, the result that indicates the largest one tree were sometimes required, and in some cases, it relative share of carrying a saw with both hands is logical was also possible to cut down several thinner trees in one for the simple reason that in this way the worker made swing. In most cases, battery shears cut down one tree his job easier by using both hands to hold a heavy tool. with one attempt. Carrying a saw with one hand by the front handle is an individual matter of each worker which mainly depends Table 4. Average work tempo with tools in the early cleaning. on the dominance of the hand. However, a slightly higher Location Worksite 1 Worksite 2 share of using the left hand while carrying a chainsaw can Two-handed billhook 27 strikes/min — be explained by the fact that the left hand was already Machete — 23 strikes/min Battery shears 26 cuts/min 19 cuts/min on the front handle of the chainsaw when cutting, and it stayed there during the transition to carrying. Transfer- Late cleaning with a petrol chainsaw consisted of v fi e ring a chainsaw to the right hand occurs if, for various work elements: cutting, carrying with both hands, car- reasons, a slightly more extended period elapses between the felling of two trees. In this case, the worker switched rying with the right hand by the front handle, carrying with the left hand by the front handle, and carrying with hands due to fatigue caused by the static work of holding the right hand by the rear handle, noting that the chain- the chainsaw. In rare cases, the worker held the saw with saw did not turn off while carrying. Table 5 shows that his right hand by the rear handle. While holding the saw in both worksites where cleaning was performed with like this, the worker is mostly stationary and used his left chainsaws, the relative share of cutting time is slightly hand to move the cut tree canopy. more than one third, which coincides with the results of When working with a battery chainsaw, since this a German study (Huber et al. 2021) while the rest of the type of chainsaw does not produce vibrations when car- time the worker carried a powered chainsaw in multiple ried, only two work elements were determined: cutting ways with a significantly higher share of carrying with and carrying (Table 6). It should be noted that chain- both hands. The diameter of the trees and their spacing saws are two-handed tools and it is understood that both Table 5. Time share of work elements in working with a petrol chainsaw. Worksite 3 Worksite 4 Day 1 Day 2 Avg. Day 1 Day 2 Avg. Work elements Avg. [%] Avg. [%] [min] [min] Cutting 90.05 90.05 90.05 37.52 79.00 86.85 82.92 34.55 Carrying BH 78.95 81.15 80.05 33.36 68.6 80.55 74.58 31.08 Carrying RF 28.35 21.15 24.75 10.31 37.50 33.7 35.60 14.83 Carrying LF 40.20 45.85 43.03 17.93 49.60 36.10 42.85 17.85 Carrying RR 2.45 1.80 2.12 0.88 5.30 2.80 4.05 1.69 Total 240 240 240 100 240 240 240 100 1 2 3 4 both hands; right hand-front handle; left hand front-handle; right hand-rear handle. Table 6. Time share of work elements in working with a battery chainsaw. Worksite 3 Worksite 4 Day 1 Day 2 Avg. Day 1 Day 2 Avg. Work elements Avg. [%] Avg. [%] [min] [min] Cutting 111.31 128.69 109.79 45.75 89.57 93.90 91.74 38.23 Carrying 108.26 131.74 130.21 54.25 150.43 146.1 148.26 61.77 Total 240 240 240 100 240 240 240 100 54 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 hands are on the handles when cutting. While working vibration levels were the result of gentler operation with with a cordless saw, the cutting work took a little longer, battery shears where the sources of vibration are short approximately two-fifths within 8 working intervals starts of electric motor and transmission, and the interac- daily. The longer cutting time, especially at Worksite 3, tion of metal blades and wood, where there are no violent can be explained by the significantly slower chain of the shocks that would create significant vibration levels. battery chainsaw. Huber et al. (2021) found in their study that while working with a battery chainsaw, the share of Table 7. Vibration levels in tools used in the early cleaning. cutting time is one-third of the productive time. How- Work tempo [strikes Vibration total Tool Location Hand or cuts/min] value – a [m/s ] hv ever, in that study, a battery chainsaw with a signic fi antly Billhook Worksite 1 27 Right 13.54 higher chain speed was used. The chain speed depends 2 Billhook Worksite 1 27 Right 11.81 Billhook Worksite 1 27 Left 14.53 primarily on the chain pitch and the rotational speed of Battery shears Worksite 1 26 Right 1.10 the drive motor. The two-stroke petrol chainsaw engine Machete Worksite 2 23 Right 23.42 has a significantly higher maximum speed than battery Battery shears Worksite 2 19 Right 0.98 1 2 two-handed operation (left hand above right); one-handed operation (right hand). chainsaws. For this reason, a petrol chainsaw chain develops a top speed of 26 m/s, while a battery chain- When calculating the daily vibration exposure A(8) saw chain develops a top speed of 18.8 m/s. The higher in the early cleaning (Table 8), the exposure time of four relative share of cutting while working with a battery hours was used, although the effective working time chainsaw is also caused by various cutting difficulties. with the tools used is not limited by the Ordinance on Thinner trees or branches were bending in contact with Occupational Safety and Health in Forestry (1986). In a battery chainsaw chain that did not have enough speed practice, workers rarely work longer than four effective to make a quick cut. Furthermore, a battery chainsaw hours in early cleaning due to unbearable heat and dif- chain is extremely thin, which resulted in frequent chain ficult working conditions. On the billhook, which is the slipping during the first cut if the guide was not laid cor- only two-handed tool in early cleaning, it has been estab- rectly on the tree, i.e. if it was slanted to the side. lished that the right hand is the reference, so the results will be observed for the right hand. The higher recorded daily exposure on the right hand is logical because that 3.2. Vibration levels and daily vibration hand was always in contact with the tool, regardless of exposure one-handed or two-handed operation, while the left hand While cleaning with a billhook, vibration levels were is not in contact with the tool in one-handed operation. higher during two-handed operation. While using both Daily exposure to vibrations on the right (and left) hand hands, the speed of the swing, and thus the force of the while working with a billhook significantly exceeded impact on the wood, was higher, which caused higher the limit value of 5 m/s , and according to EU Directive recorded vibrations (Table 7). For this reason, one- 2002/44/EC (2002) such work should not be continued. handed work with a two-handed billhook creates sig- At the level of vibration occurring on the right hand in the nificantly less vibration than work with a one-handed two-handed operation, it took 16 minutes of work (con- billhook that swings slightly faster, which is supported by tinuous striking) to reach an exposure of 2.5 m/s or an a previous study (Bačić et al. 2020) where a vibration level action value, and 65 minutes of work to reach a limit value of 19.34 m/s was recorded on a one-handed billhook. of 5 m/s . On the right hand in the one-handed opera- The highest level of vibration was recorded while clean- tion, it took 22 minutes to reach the action value, and 86 ing with a machete, which was expected. Namely, the minutes to the limit value. Daily exposure to vibrations machete, unlike a billhook, did not have a wooden handle was highest while working with a machete, and the result that separates the metal blade, that is the source of the obtained was similar to the result from the previous study vibration, from the hand and reduced the transmission of (Bačić et al. 2020) on a one-handed billhook of 13.7 m/s . vibration to the hands of workers. The role of the handle The calculated value was extremely high, and it took in vibration transmission is significant (Beckley 2019). only 5 minutes of work to reach the action value, while The metal blade of the machete effectively conducted the the limit value took 22 minutes of work. While working vibrations created by striking the wood to the handle of with battery shears, for both observed locations, a very the machete (worker’s hand) which consisted of two mir- low daily exposure to vibration was calculated, and it ror pieces of wood attached to the metal part. The small took over 24 hours to reach the action and limit values. dimensions of the machete handle do not have a great It should be kept in mind that the shock (vibration) while ability to dampen the vibrations created (Kocjančić working with hand tools is of very short duration and that 2018). The level of vibration recorded while working with the frequency characteristics of this type of vibration were battery shears is extremely low. There is a minimal differ- not investigated in this paper. This study relies on fre- ence due to the two different work tempos at which the quency weighting algorithms that are incorporated into vibrations were recorded. Slightly higher vibration levels the used instrument (vibrometer) and thus find these were recorded at a faster tempo with battery shears. Low results relevant. 55 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 2 2 Table 8. Daily vibration exposure in tools used in the early declared 4.6 m/s on the front handle and 3.9 m/s on the cleaning. rear handle (MSA 200 C–B 2022), but with an approxi- Tool Billhook Machete Battery shears mately similar ratio between the front and rear handle. Location Worksite 1 Worksite 2 Worksite 1 Worksite 2 2 2 2 2 Right hand A(8) 9.3 m/s 16.6 m/s 0.8 m/s 0.7 m/s Left hand A(8) 8.8 m/s — — — Table 9. Vibration levels in chainsaws used in the late cleaning. Work element Hand Handle The petrol chainsaw generated vibrations in all work elements, while the battery chainsaw vibrated only when Chainsaw type cutting. Vibration levels are presented according to the measurement combinations (Table 9). While cutting 1 × × × 4.05 with a petrol chainsaw, higher levels of vibration were 2 × × × 3.62 recorded on the front handle which is not in line with 3 × × × 3.57 the results of Goglia et al. (2012) where higher levels of Petrol chainsaw 4 × × × 5.62 × × × 5.69 vibration in cutting are recorded on the rear handle (Stihl 5 × × × 5.69 MS 260) and the results of a German study (Huber et al. 6 × × × 6.30 1 × × × 5.15 2021) where a Stihl MS 201 C chainsaw is used. When Battery chainsaw 2 × × × 4.29 carrying a chainsaw with both hands, a higher level of 1 2 carrying with one hand; carrying with both hands. vibration was recorded on the rear handle, as noted by Goglia et al. (2012) but with higher values. Furthermore, According to the results of daily exposure to vibration the results obtained also coincide with the above study while working with a petrol chainsaw (Table 10), higher while carrying a chainsaw with one hand (left and right) exposure was recorded on the right hand, while the left by the front handle and the right hand by the rear han- hand was more exposed on the battery chainsaw, and dle where the highest level of vibration was recorded. they are considered a reference. In both observed loca- Compared to the declared vibration levels of 3.5 m/s tions, lower exposure to vibrations was observed while on both handles (MSA 200 C-B 2022), higher vibration working with a battery chainsaw as in previous studies levels were recorded in all measuring combinations for (Colantoni et al. 2016; Neri et al. 2018; Poje et al. 2018). petrol chainsaws. Vibration exposure while working with a petrol chainsaw An interesting result is that slightly higher levels of at both worksites exceeded the exposure action value of vibration while cutting were recorded on a battery chain- 2.5 m/s , while when working with a battery chainsaw saw in contrast to the Slovenian study (Poje et al. 2018) at Worksite 3, the estimated exposure was exactly at the and the German study (Huber et al. 2021). In these stud- exposure action value. It took 1 hour and 53 minutes to ies, higher vibration levels are also recorded on the front reach the exposure action value with a battery chainsaw, handle of the battery chainsaw. The Makita DUC302Z while it took 7 hours and 32 minutes to reach the expo- battery chainsaw is tested in a Slovenian study and the sure limit value. Differences in daily vibration exposure Stihl MSA 220 C in a German study. A probable reason for (on the same chainsaw) between the two worksites are the increase in recorded vibration levels, apart from the minimal and stemmed from differences in the relative different types of chainsaws tested, is the fact that the bat- time shares of work elements. tery chainsaw used in this study had a lower mass than the mentioned chainsaws causing higher vibration levels at Table 10. Daily vibration exposure in chainsaws used in the work (Malchaire 2020). The observed chainsaw had less late cleaning. mass because it did not use a small battery that is stored Chainsaw type Petrol chainsaw Battery chainsaw in the housing, which increases its total mass, but instead Location Worksite 3 Worksite 4 Worksite 3 Worksite 4 2 2 2 2 Left hand A(8) 2.8 m/s 2.8 m/s 2.5 m/s 2.3 m/s used a backpack battery. It should be borne in mind that 2 2 2 2 Right hand A(8) 3.1 m/s 3.2 m/s 2.0 m/s 1.9 m/s different vibration recording methods and different types of chainsaws can also give different results of vibration level measurements. In this research, the methods and 4. Conclusion conditions of vibration recording were designed to rep- resent the actual e fi ld conditions as faithfully as possible, Vibration levels and daily vibration exposure while clean- while meeting the applicable measurement standards. ing with battery shears are many times lower compared Furthermore, the battery chainsaw used in this study was to cleaning with a two-handed billhook and machete. The not equipped with a conventional anti-vibration system work tempo with all the observed tools in the early clean- which is common for battery chainsaws that do not pro- ing is similar, but the technique and mode of operation duce high levels of vibration due to the circular motion of of the tool are quite different. Cutting a tree using battery their drive motor. By the interaction of chain and wood shears was u fl ent, without jerks and sudden movements, which is a heterogeneous material, certain deviations in while cutting with hand tools was quite the opposite, the measured vibration levels occur. The recorded vibra- moreover, the greater the force of impact - the better the tion levels on the battery chainsaw were higher than the effect of cutting. High forces during work and sudden Measuring combination Cutting Carrying Left Right Front Rear Vibration total value –a [m/s ] hv M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 stops of tools when striking wood had caused very high Bačić, M., Šušnjar, M., Zečić, Ž., Koren, S., Kolarić, recorded vibration levels in hand tools, and consequently M., Pandur, Z., 2020: Daily vibration exposure in high daily exposure. forestry: the difference between manual and motor- Although the recorded vibration levels on the used manual cleaning methods. Sigurnost, 62:265–274. battery chainsaw were higher than on the petrol chain- Barnes, R., Longley, E. O., Smith, A. R. B., Allen, J. G., saw, the daily exposure was lower. The complete absence 1969: Vibration disease. Medical Journal of Australia, of vibrations caused by the rotation of the drive motor in 1:901–905. the work element of carrying the battery chainsaw had Beckley, B., 2019: One Moving Part: The Forest Service an extremely large impact on daily exposure. Due to the Ax Manual. Missoula, MT, p. 45–49. slower chain, the duration of the cutting with a battery Bower, A., Qi, Y., Bazilevs, Y., 2022: E40 Dynamics and chainsaw was somewhat longer, and it can be concluded Vibrations – lectures. Brown University, School of that using newer models of battery chainsaws, with Engineering, Providence, USA. higher chain speed, would shorten the total duration of Brammer, A. J., Pyykkö, I., 1987: Vibration-induced the cutting at the expense of increasing the duration of neuropathy: Detection by nerve conduction measure- carrying, which would additionally lower the daily vibra- ments. Work, Environment & Health, 13:317–322. tion exposure. Colantoni, A., Mazzocchi, F., Cossio, F., Cecchini, M., The recorded vibration levels, as well as the daily Bedini, R., Monarca, D., 2016: Comparisons between exposure, were many times higher in the early cleaning battery chainsaws and internal combustion engine with a billhook and machete than in the late cleaning chainsaws: performance and safety. Contemporary with a chainsaw. In operational forestry, workers with Engineering Sciences, 9:1315–1337. reduced working ability are excluded from working with de Oliveira, F. M., Lopes, E. S., Rodrigues, C. K., 2014: a chainsaw due to a diagnosed white fingers disease and Evaluation of the physical workload and biomechani- the fact that the chainsaws are vibrating tools. Some of cal of workers at manual and semi-mechanized mow- these workers are transferred to silvicultural work with ing. Cerne, 20:419–425. hand tools such as billhook and machete which are not Forouharmajd, F., Yadegari, M., Ahmadvand, M., considered vibrating tools. From the above mentioned, it Forouharmajd, F., Pourabdian, S., 2017: Hand-arm can be concluded that a detailed revision in the classic fi a - Vibration Effects on Performance, Tactile Acuity, and tion of tools is needed, considering their ability to produce Temperature of Hand. Journal of Medical Signals and and transmit harmful vibrations to the operator and that Sensors, 7:252–260. using the current classic fi ation can be unfavorable for the Goglia, V., Žgela, J., Suchomel, J., Đukić, I., 2001: Expo- worker and his health. sure to hand-arm transmitted vibration at forest nurs- ery and thinning. Human Resources Management and Ergonomics, 5:45–55. Goglia, V., Žgela, J., Suchomel, J., Đukić, I., 2012: The Acknowledgments effectiveness of forest pre-commercial thinning in The research was cofunded by the Hrvatske šume Ltd. within the context of Directive 2002/44/EC. Šumarski list, the Project «Ergonomska pogodnost i ekonomska isplativost  136:471–478. primjene akumulatorske motorne pile i akumulatorskih škara Huber, M., Hoffmann, S., Brieger, F., Hartsch, F., Jaeger, u radovima njege i čišćenja jednodobnih sastojina», project  D., Sauter, U. H., 2021: Vibration and Noise Expo- number DIR-01-17-3432/02. sure during Pre-Commercial Thinning Operations: What Are the Ergonomic Benefits of the Latest Gen- eration Professional-Grade Battery-Powered Chain- references saws? Forests, 1: 1120. Anić, I., 2007: Uzgajanje šuma I – internal script. Fac- Jobidon, R., Roy, V., Cyr, G., 2003: Net effect of compet- ulty of Forestry and Wood Technology, University of ing vegetation on selected environmental conditions Zagreb, p. 1–97. and performance of four spruce seedling stock sizes Araki, S., Honma, T., Aoyama, K., 1976: Peripheral after eight years in Quebec (Canada). Annals of For- nerve conduction velocities in chainsaw operators. est Science, 60:691–699. Japanese Journal of Industrial Health, 18:516–520. Kocjančić, L., 2018: Izbira sekaške sekire glede na jakost Axelsson, S-A., 1968: Analysis of Vibration in Power tresenja in obremenitve ledvenega dela. B. Sc. thesis, Saws. Studia Forestalia Suecica, 59:1–47. Univerza v Ljubljani, Biotehniška fakulteta, Oddelek Bačić, M., Landekić, M., Šušnjar, M., Šporčić, M., Pan- za gozdarstvo in obnovljive gozdne vire. dur, Z., 2019: Movement analysis of a worker in the Landekić, M., Bačić, M., Pandur, Z., Šušnjar, M., 2020: forest cleaning activities. In: Proceedings of the 52nd Vibration Levels of Used Chainsaws. Forests, 11:1– International Symposium on Forestry Mechaniza- tion: “Exceeding the Vision: Forest Mechanisation of the Future”, Sopron, 6–10 October 2019. 57 M. Bačić / Cent. Eur. For. J. 69 (2023) 49–58 Malchaire, J., 2020: Vibrations Mains-Bras: Serie Strat- Tambić Bukovac, L., Šenjug Perica, M., 2017: Raynau- egie Sobane–Gestion des Risques Professionnels. dov sindrom. Paediatria Croatica, 61:38–42. Brochure, Service public fédéral Emploi, Travail et Taylor, W., Pearson, J., Kell, R. L., Keighley, G. D., 1971: Concertation sociale, Brussels, p. 1–70. Vibration syndrome in Forestry Commission chain Malinowska-Borowska, J., Harazin, B., Zieliński, G., saw operators. British Journal of Industrial Medicine, 2012: Measuring coupling forces woodcutters exert 28:83–89. on saws in real working conditions. International Thompson, D. G., Pitt, D. G., 2003: A review of Canadian Journal of Occupational Safety and Ergonomics, forest vegetation management research and practice. 18:77–83. Annals of Forest Science, 60:559–572. Malinowska-Borowska, J., Harazin, B., Zieliński, G., Other sources 2011: The influence of wood hardness and logging Directive 2002/44/EC, 2002: The mimimum health operation on coupling forces exerted by lumberjacks requirement regarding the exposure of workers to the during wood harvesting. International Journal of risks arising from physical agents (vibration). Ofc fi ial Industrial Ergonomics, 41:546–550. Journal of the European Communities,177:13–19. Malinowska-Borowska, J., Zieliński, G., 2013: Coupling ISO 11681-1:2011. Machinery for forestry – Portable forces exerted on chain saws by inexperienced tree chain-saw safety requirements and testing – Part 1: fellers. International Journal of Industrial Ergonom- Chain-saws for forest service. International Standard ics, 43:283–287. organization, Geneva, p. 1–22. McGeoch, K. L., Lawson, I. J., Burke, F., Proud, G., ISO 5349-1:2001. Mechanical vibration – Measurement Miles, J., 2005: Diagnostic criteria and staging of and evaluation of human exposure to hand transmit- hand-arm vibration syndrome in the United King- ted vibration. Part 1: General requirements. Interna- dom. Industrial Health, 43:527–534. tional Standard organization, Geneva, p. 1–26. Miura, T., Kimura, K., Tominaga, Y., Kimotsuki, K., ISO 5349-2:2001. Mechanical vibration – Measurement 1965: On the Raynaud’s Phenomenon of Occupa- and evaluation of human exposure to hand-transmit- tional Origin due to Vibrating Tools–ts Incidence in ted vibration – Part 2: Practical guidance for meas- Japan. Journal of Science of Labour, 42:725–747. urement at the workplace. International Standard Neri, F., Laschi, A., Foderi, C., Fabiano, F., Bertuzzi, organization, Geneva, p. 1–39. Lucia., Marchi, E., 2018: Determining noise and ISO 8041-1:2017. Human response to vibration – Meas- vibration exposure in conifer cross-cutting opera- uring instrumentation – Part 1: General purpose tions by using li-ion batteries and electric chainsaws. vibration meters. International Standard organiza- Forests, 9:1–13. tion, Geneva, p. 1–106. Poje, A., Potočnik, I., Mihelič, M., 2018: Comparison of MS 261. Available online: https://unikomerc-uvoz.hr/ Electric and Petrol Chainsaws in Terms of Efficiency ms-261 (accessed on 19 April 2022). and Safety When Used in Young Spruce Stands in MSA 200 C-B. Available online: https://unikomerc-uvoz. Small-Scale Private Forests. Small-Scale Forestry, hr/msa-200-c-bq-aku-pila (accessed on 19 April 17:1–12. 2022). Seppäläinen, A. M., 1972: Peripheral neuropathy in Ordinance on Occupational Safety and Health in For- forest workers. A field study. Work, Environment & estry. Official Gazette, 10/86, 1986, p. 1–18. Health, 9:106–111.

Journal

Forestry Journal – de Gruyter

Published: Mar 1, 2023

Keywords: forest cleaning; hand tools; battery tools; vibration levels; vibration exposure

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