When transporting timber, the high variability of species, assortments and moisture content of the wood raw material does not allow the weight of the transported timber to be precisely determined. This often contributes to the excessive weight loading of the entire truck unit. The aim of the research is to present the variability of the total weight of truck units with wood cargoes (GVW-gross vehicle weight) depending on the weight of the empty unit and the transported timber load, as well as to analyze the changes in GVW, unit loads of wood and load on individual truck unit axles depending on the season. This study analyzes the total weight of truck units for 376 transports of Scots pine timber at different times of the year. The total weight of the truck units depends on the weight of an empty unit and the weight of the load. GVW was determined by using a weighbridge to weigh the vehicles and then the empty unit after unloading. The weight of the load was obtained as the difference between GVW and the tare. It was found that GVW differed significantly depending on the truck unit used, ranging from 43.60-58.80 Mg, often exceeding permissible limits for public roads. The individual axle loads for various truck units were also analyzed. The obtained results indicate that these loads are more equally distributed in the case of five-axle trucks compared to six-axle ones.
The research was conducted on a forest road on the territory of the State Forests in Poland, in the Brzeziny Forest District, where eight test sections with a total length of 422 m were created with different pavement system on a low-bearing soil substrate (clay, silt loam) as part of the road reconstruction in 2016. The bearing capacity of the pavement was evaluated based on the static strain modulus ME MN·m−2 by measuring with a statistic plate (VSS), the dynamic deformation modulus Evd MN·m−2 obtained from lightweight deflectometer measurements, and the elastic deflection of the pavement Us mm evaluated from Benkelaman beam measurements. It has been shown that pavements made of crushed aggregate and common gravel on timber roller substructure maintain good bearing capacity parameters, where the average values of secondary modulus of strain are above 130 MN·m−2, and in the case of pine rollers, this modulus has increased. Pavements on low-bearing soils reinforced with willow brushwood mattresses have low bearing capacity parameters, with averages of 26.09 ≤ MEII ≤ 53.93 and 22.1 ≤ Evd ≤ 39.1 MN·m−2, but the technical condition of the pavement makes it possible to continue carrying out forestry-related transportation. The research confirms the possibility of reinforcing soils with poor bearing capacity with wooden rollers, and in the case of willow mats for roads with light truck movements.
Forest roads are characterized by low traffic, but heavy timber haulage trucks have a significant influence on road conditions and usually exceed the limit of 80-100 kN per axle. The excessive weight of the trucks degrades the road surface and the forest environment. This article presents the results of a study of timber transport loads from their places of acquirement (forest districts) to the recipient (a large sawmill). The analysis includes the parameters of the timber transport vehicles and focuses especially on the gross vehicle weight (GVW), the total weight of empty truck and trailer during transport, and the weight of their loads. Scania, Iveco, Man, and Mercedes trucks with trailers and semitrailers designed for large-size pine timber transport were analyzed. ANOVA results revealed that all 80 analyzed vehicles exceeded the permitted GVW in the range from 2.28 to 19.94 Mg, transporting from 20.1 to 37.5 m 3 of timber. The coefficient of determination between the amount of hauled timber and the GVW equaled 62.7%. Research conducted previously concluded that forest roads with ground and gravel surfaces are not suitable for overloads of 120-150 kN per axle. Therefore, it is necessary to find a logistical solution that will allow the load volume to be maintained at an acceptable level without destroying the forest road surface.
Proper measurements are extremely significant for the forest owner, the harvesting company, the hauler, the final buyer, and the wood processing company. The accuracy of round wood volume determination is of fundamental importance in planning and accounting for individual processes related to the wood trade. It is the basis for determining the maximum quantity in single load of wood that allows for using the permissible total gross vehicle weight. The determination of wood load in cubic meters does not allow unequivocally determining its weight, which often leads to overloading of vehicles. This paper presents a comparison of the photo-optical method for determining the volume of wood to be transported with the real measurement and determination of the weight of a load and the total gross vehicle weight (GVW) with the simultaneous application of conversion factors determining the weight of the load from the volume of wood. The measurement included 23 broadleaf round wood piles (193.73 m3) and 14 coniferous round wood piles (149.23 m3). The measurement error for broadleaf wood piles ranges from −47.67% to 63.16%, and from −43.31% to 24.72% for coniferous wood piles. Determination of the volume of a broadleaf wood pile using the iFOVEA method had an average error of 1.34%, while the Timbeter method had an average error of −1.83%. In the coniferous wood pile measurement, the error is −12.82% and 2.41%, respectively. Verification of the volume of the large-sized wood indicated on the delivery note (reference value) on the log sorting line (by laser scanning) showed larger volumes by 0.10 m3 to 2.54 m3, giving a percentage error of 0.35% and 8.62%, respectively. As a consequence of the application of such methods for determining the weight of wood loads, the transport truck sets are often significantly overloaded, which has a significant impact on the accelerated degradation of roads and safety in traffic and timber transportation.
This study is on the ecological aspects and interest of the State Forest National Forests Holding (SF) units in reinforcing the ground subgrade by using timber raft construction and brushwood mattresses in forest road construction. The aim of the study was to analyse the technical parameters of forest roads made on a ground subgrade reinforced with timber raft construction and brushwood mattresses. As part of the research, the scope of SF units' application of technological solutions and the parameters of existing forest district roads made on a timber substructure were determined. A road with reference sections using different variants of subgrade reinforced with timbers logs (oak, pine) and brushwood mattresses were studied. The technical parameters of features ensuring usability, such as, among others, the bearing capacity of the pavement, were selected for the analysis. The ability of the tested pavements to support vehicle axle loads was determined based on the deflection of the surface as well as the primary (M EI ) and secondary (M EII ) deformation modulus with a calculated deformation indicator (I 0 ). The deformation modulus ME of the pavement and road subgrade were determined using a VSS plate with a diameter of 300 mm. It indicated a large range of results of secondary deformation of surfaces using timber raft construction (107-204 MN·m -2 ) and brushwood mattresses ), which are dependent mainly on the diameter of the logs used, their arrangement and the road fill used.
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