Rutting measurements are a significant part of scientific research on the impact of forest vehicles on the forest soils and damage to the forest transport infrastructure. Although photogrammetric ...methods of measurement or measurements based on LiDAR (light detection and ranging) data are increasingly being used for rutting measurements, the previous research conducted using these methods indicated the challenge of recording water-filled ruts. For this reason, it is necessary to define a reliable method of rutting field measurement in lowland forest stands characterized by a high level of groundwater that fills the ruts shortly after the passage of forest vehicles. This research analyzed the measurement accuracy using a total station and a GNSS RTK device with a CROPOS correction base in relation to the measuring rod that represented the reference method. Based on recorded and processed data, ruts are displayed in two ways: as net and as gross value of rut depth. The analysis of net rutting revealed a statistically significant difference between the calculated rut depths based on measurements with a GNSS RTK device and other methods. On average, the net rutting measured by the GNSS RTK device was 2.86 cm smaller than that of the reference method. When calculating the gross rutting, which consisted of the net rut depth and the bulge height, no statistically significant difference was found between the measurement methods used. Based on this result, the bulge height was also analyzed, and showed a statistically significant difference between the data recorded by the GNSS RTK device and other methods. It can be concluded that measuring the depth of ruts with a total station gives accurate data and represents the optimal modern field measurement method for the same or similar terrain conditions. In contrast, the GNSS RTK device, which constantly gives higher elevation points, can be used to measure gross rutting.
During the seven-year research period, the average annual removal was by 3274 m3 higher than the average annual removal prescribed by the existing management plan (MP). The main reason lies in the ...high amount of salvage felling volume at 55,238 m3 (38.3%) in both the main and the intermediate felling due to oak dieback. The analysis of forest accessibility took into account the spatial distribution of cutblocks (with ongoing felling operations) and the volume of felled timber for two proposed factors: (1) the position of the cutblock and (2) the position of the removal. Cutblock position factor took into account the spatial position of the felling areas/sites, while removal position factor besides the spatial reference took into account the amount of felled timber (i.e., volume) both concerning forest infrastructure network and forest operations. The analysed relative forest openness by using geo-processing workflows in GIS environment showed four types of opening areas in the studied management unit (MU): single-opened, multiple-opened, unopened and opened areas outside of the management unit. Negative effects of the piece-volume law and low harvesting densities on forest operations are highlighted in this research due to high amount of salvage felling particularly in the intermediate felling by replacing timber volume that should have come from thinnings.
Forest roads, as a prerequisite for high-quality forest management, should be optimally distributed in order to avoid negative environmental impacts and to best fulfill their task. In the design ...phase of forest roads, it is necessary to know which factors influence most the volume of earthworks to enable the designer to best adapt to the terrain requirements. In this paper the impact of an average cross terrain slope and carriageway value of a forest road on cut and fill volume is analyzed. The research was carried out in the area of the management unit Trovrh–Kik, characterized by irregular terrain with slopes ranging between 27 and 58%, and on some micro locations even up to 84%. On eight forest roads, based on standard cross-section profiles, the influence of the average cross terrain slope and carriageway value (difference between ground level and grade level) of the forest road on the cut and fill volume per 1 m of the forest road route was analyzed. The obtained coefficients of determination indicate a strong correlation between the cut volume and carriageway value (R2 = 0.6841), and a moderate correlation between the fill volume and carriageway value (R2 = 0.5619). Unlike the influence of carriageway value on the cut and fill volume, the correlation between the cross terrain slope and fill volume is weak (R2 = 0.2076) or moderate in the case of the cut volume (R2 = 0.3167). On the basis of the analyzed standard cross-section profiles, it was determined that the carriageway value was 0.051 m, where the difference between the cut and fill volume was minimum and the average actual carriageway value was determined to be −0.09 m. It can be concluded that, on terrains with large and varying slopes, there is no unique model or terrain factor that could describe the earthworks required in the construction of a forest road. However, it is beyond doubt that the increase in the carriageway value and cross terrain slope caused the increase in the aforementioned volumes.
The use of forestry vehicles in mechanised harvesting systems is still the most effective way of timber procurement, and forestry vehicles need to have high mobility to face various terrain ...conditions. This research gives boundaries of planning timber extraction on sloped terrain with a cable skidder, considering terrain parameters (slope, direction of skidding, cone index), vehicle technical characteristics and load size (5 different loads) relying on sustainability and eco-efficiency. Skidder mobility model was based on connecting two systems: vehicle-terrain (load distribution) and wheel-soil (skidder traction performance) with two mobility parameters: (1) maximal slope during uphill timber extraction by a cable skidder based on its traction performance (gradeability), and (2) maximal slope during downhill timber extraction by a cable skidder when thrust force is equal to zero. Results showed mobility ranges of an empty skidder for slopes between −50% and +80%, skidder with 1 tonne load between −26% and +63%, skidder with 2 tonne load between −30% and +51%, skidder with 3 tonne load between −34% and +39%, skidder with 4 tonne load between −35% and +30% and skidder with 5 tonne load between −41% and +11%.These results serve to improve our understanding of safer, more efficient timber extraction methods on sloped terrain.
Skidder mobility during timber extraction is defined by: 1) basic dimensional features of the vehicle, 2) ability to overcome obstacles during movement, 3) traction performance and 4) environmental ...soundness. Traction performance depends on the ground conditions (soil bearing capacity) and the total effect of all forces on the vehicle. In downhill skidding, the skidder is under great influence of parallel component of forces, adhesion weight and longitudinal terrain slope, which combined result in negative traction force, torque and thrust force. When the horizontal component of rope force is equal to zero i.e. the moment when the weight of the load and resistance to traction are in equilibrium, the slope angle a is a function of load mass distribution factor and skidding resistance factor. This is a "turning point" that can be defined as a critical slope because the load starts to push the vehicle downhill, which results in negative horizontal component of rope force. Depending on skidder Ecotrac 120V dimensional features, centre of gravity, load mass distribution factor, skidding resistance factor of previous research, five different loads were analyzed (1 to 5 tonnes) in order to define the critical slope angle for each of them. Critical slope for downhill skidding of 1 tonne timber is on longitudinal slope of -26%, for 2 tonne timber on -30%, 3 tonne timber on -34%, 4 timber on -38% and for 5 tonne timber on -43% of terrain longitudinal slope. Even though skidding bigger load increases vehicle mobility to even greater slope angles, the most important in downhill skidding, is to avoid blocking of the wheels, which will lead to a complete vehicle slippage and the driver must be constantly aware of that fact. The general recommendation should be that skidding small loads (1 to 3 tonnes) downhill is suitable for smaller longitudinal terrain slopes (up to maximum -34%), while the heavier the load, the further down the slope the skidder can go. The load of 5 tonnes "anchors" the skidder better and therefore it can go on terrain slopes up to -43%, during which less traction force is used (torque is used for braking) and skidder pulls the load by its own weight. It can be concluded that extending the operating range of skidder onto steeper slopes with heavier loads has the potential to decrease harvesting costs and increase productivity. Keywords: skidder, downhill timber extraction, rope force, critical slope
This paper discusses the key issues of forestry workers training in Croatia, especially dealing with the providers of vocational training, their profile, training procedures and measures necessary ...for training improvement. A combined approach of literature review, internet search and questionnaire of training providers was applied in order to collect data on training programs conducted in Croatia. The research was conducted during 2016, and it included 94 legal entities authorized for occupational safety training in the Republic of Croatia, with respect to safe working practice training and vocational training for operating machinery (chainsaw and/or skidder). The analysis used basic descriptive statistics. Research results showed that 30.85% of the analyzed legal entities provide only training for safe working practice, 15.96% provide both trainings--safe work practice and vocational training for operating machinery, 5.32% of the analyzed entities provide only vocational training for operating machinery, 31.91% do not carry out any form of training in forestry, while 15.96% refused to answer questions. On the other hand, 15.56% of the legal entities, which do not carry out any training or did not answer these questions, have on their official website services posted for vocational training in operating machinery (chainsaw and/or skidder). The key findings of the conducted research have pointed out the great heterogeneity amongst providers of forestry workers training, and certain reductions or limitations in the current training programs, both from the aspect of duration of the theoretical and practical training, and the use of non-transparent criteria and standards in the assessment of training. As an example of successful solution in forestry workers training, European Chainsaw Standard model (ECS) is shortly presented in the paper. Discussion and conclusion sections provide an overview of legislative and organizational requirements for the application of previously developed European model (ECS) in developing the certification system for training of for estry workers in Croatia. Keywords: forestry, chainsaw worker, health and safety, vocational training, certification, Croatia
Background and Purpose: Terrain trafficability and vehicle mobility during timber extraction are highly influenced by terrain characteristics, as well as by soil bearing capacity. Insufficient ...planning, too heavy vehicles, excessive traffic, poor soil knowledge, together with bad weather conditions, cause severe disturbance to forest soil. Damage to the forest ecosystem arises due to felling and timber extraction operations, regardless of the technical means used in this process. Traffic intensity plays an essential role in soil compaction because deformations can increase with the number of passes, which may lead to excessive soil disturbance.
Materials and Methods: The research was conducted in Zalesina, a hilly and pre-mountainous part of Gorski kotar, Croatia, in two management units (MUs) comprising of 569.64 ha of selective beech and fir forests. Physical and mechanical properties of forest soil, essential for vehicle mobility and terrain trafficability during timber extraction are based on measuring the following soil parameters: 1) soil penetration resistance, 2) soil shear strength, and 3) current soil moisture. Measurements were made during one calendar year, on five sampling plots (three in MU "Belevine" and two in MU "Kupjački vrh") chosen on the prevailing soil types in both MUs.
Results: The highest values of cone index and shear strength were recorded in July which was the warmest and driest month with only 7 rainy days. Current soil moisture was the lowest in July at φ=15.26% vol, while the lowest values of cone index were from October to January with precipitation at its climax from September to January with cumulative 1232 mm of rain and 846 cm of snow. Lower values of penetration resistance were in MU "Kupjački vrh" at 0.96 MPa, which is related to overall terrain structure of high karst and surface roughness, making the sampling of plots difficult. By comparing cone index values (CI15) and the mean values between 5 and 25 cm of depth (CI5-25), the variation coefficient indicates a lower variability of CI5-25 values on four out of five sampling plots. However, t-test showed no statistically significant difference between these soil parameters.
Conclusions: Data regarding soil bearing capacity in a map form as an additional layer to other maps of stand characteristics would ensure better opportunities for planners or operators to reduce and avoid rutting and soil compaction. Measured data on penetration resistance, soil shear strength and current soil moisture have not only given in a simple and a fast manner the in situ stand conditions, but they have also shown their dependence on climatic conditions.
This paper deals with the severity of accidents in forest operations in Slovenian state forests in the period 1990–2005. A total of 846 accidents were analyzed. Most accidents happened in felling ...(68% and 20 lost days), and somewhat less during skidding (24% and 19 lost days). Most injuries were caused by direct contact of the tree parts (60% and 20 lost days) with stones, rocks and surface (24% and 21 days lost days). Power saw only caused 6% of injuries (17 lost days). Contusion was the most frequent type of injury in accidents due to stroke (56%), open sore (19%) and sprain with muscle strain (11%). Severity of injuries of extremities (20.5 lost days) seems to be different from face injuries (11.6 lost days). It can be concluded that the results are useful for implementation in everyday forest operations based on safety and accident prevention.
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