Time consumption, productivity, and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions.An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning.Based on the identified elements of skidding work phase and 130 recorded cycles,we calculated the models for effective time consumption,total productivity,and unit cost.The validity of the model was tested at 95% confidence interval.The average load volume per cycle was 2.82 m 3,average one way skidding distance was 450 m,and the average slope was 18%.The average travel speed of unloaded skidder was 5.8 km·h-1,and the average speed of loaded skidder was 0.1 km·h-1 higher than the speed of the unloaded ones.The travel speed was predominantly affected by longitudinal slopes and types of strip roads.The average speed of pulling the cable was 1.16 km·h-1,and that of load winching was 0.74 km·h-1.The average outputs in skidding was 10.6 m 3 ·h-1 and the unit cost was 12.1 US$ per hour.The time consumption and productivity of skidding depends on distances and slope,number of logs per cycle,volume,log length,etc.However,the influence of variables is not the same.     

Modeling spatial variability in the life-cycle costs of low-volume forest roads

Cost estimation is probably the most decisive factor in the process of computer-aided, preliminary planning for low-volume road networks. However, the cost of construction is normally assumed to be route-independent for a specific project area, resulting in sub-optimal layouts. This is especially true for mountainous terrain and in areas with unstable subsoil. Here, we present a model for more accurately estimating spatial variability in road life-cycle costs, based on terrain surface properties as well as geological properties of the subsoil. This parametric model incorporates four structural components: embankment, retaining structures, pavement, and drainage and stream-crossing structures. It is linked to a geo-database that allows users to derive location-specific parameter values as input. In applying this model, we have demonstrated that variability in costs ranges widely for mountainous areas, with the most expensive construction being approximately five times greater there than on more favorable sites. This variability strongly affects the optimal layout of a road network. First, when location-specific slope gradients are considered, costs are reduced by about 17% from those calculated via currently available engineering practices; when both slope gradient and geotechnical formations are included, those costs are decreased by about 20%. Second, the length of the road network is increased by about 4% and 10% respectively, compared with current practices.     

A South African softwood sawtimber supply chain case study

Supply chain management principles were analysed by investigating the effects of smaller-scale and incremental interventions in a forest-to-mill value chain on financial returns and forest resource use in an Eastern Cape case study area. Three previous studies provided input by determining fibre balances, a terrain factor, and primary and secondary transport travel speeds and efficiencies. Network analysis, combined with raster-based GIS, analysed different primary and secondary transport scenarios. The forest road network was repeatedly refined through theoretical removal of lower-class roads and subsequent upgrades of remaining roads, and the timber resource flowed over the remaining road network to the mill. Four road networks, including the existing and unrefined network, were studied. With sequentially improved secondary transport travel speeds, primary transport efficiency and fibre use, the net financial returns of the various scenarios were determined by applying discounted cash flow analysis (NPV). To address all possible combinations, 144 unique scenarios were created. The highest NPV achieved was R300.8 million associated with a highly upgraded road network and associated fast secondary transport speeds, cable skidder extraction, motor-manual felling and cross-cutting at the merchandising yard, all factors at optimal performance. The lowest NPV was R40.4 million associated with a simplified road network, low secondary transport speeds, cable skidder extraction, mechanised felling, and roadside merchandising and at status quo systems performance. Examination of individual factors found systems performance, secondary transport speeds and road network had the greatest influence, with systems performance and fibre losses providing the largest impact. Secondary transport speed followed as nine of the top 10 NPV scenarios were achieved with the highest possible road design speeds. Higher-class networks consistently outperformed the baseline and simplified scenarios. Harvesting system had limited effect. When operating at peak performance, using a merchandising yard becomes a better choice. There was no clear difference in terms of felling method or skidder type. It is clear that the optimised use of potentially the most productive machine, for example in one system, does not provide the best final results and that it is the basic harmonisation of all factors that must be taken into account. As in all three previous and related studies, the human element played a role.     

Time Prediction Models and Cost Evaluation of Cut-To-Length (CTL) Harvesting Method in a Mountainous Forest

Time equations are derived for felling with chainsaw, skidding with cable wheeled skidder, loading with grapple hydraulic loader and trucking of logs within a cut-to-length harvesting method. The continuous time study method was applied to collect data for felling, skidding, loading and a transportation model. Multiple regression analysis via SPSS software was applied to develop the time models. Felling time was found to be highly dependent on diameter at breast height. Skidding distance, winching distance, slope of the trail and piece volume were significant variables for the skidding time prediction model. The loading time model was developed considering piece volume. Transportation distance and load volume were used as independent variables in modeling the transportation time. The net production of felling was estimated at 12 trees/h (56.65 m³/h). The net production rates for skidding, loading and traveling averaged 18.51, 41.90 and 3.32 m³/h respectively. The total cost of harvesting from stand to mill was estimated 19.70 €/m³. The skidding phase was the most expensive component of the cut-to-length method. The bucking and delimbing components were less costly than the other logging phases. The results of this study can be used for harvesting planning and productivity optimization.     

Forestry operations in the European mountains: a study of current practices and efficiency gaps

Timber production is an important ecosystem service of European mountain forests. This paper aimed to assess the current practices in logging operations and to identify the efficiency gaps in timber production. The study was located in 7 case study areas from representative European mountain ranges, where 632 logging operations were analysed. The focus was on road infrastructure, transport systems, harvesting methods and extraction technologies. Often inappropriate technology was used in steep terrain; there was no correlation between the average slope and the selection of harvesting systems (HS). Skidding was the most common extraction method (75%), while cable yarding and forwarding had shares of 15% and 8%. The mean road density was 18.5?m?ha^?1. The mean extraction distance was 501?m. The mean harvesting and extraction productivity were 9.0 and 10.2?m³?h^?1; the mean costs were 11.1 and 11.7?€?m^?³, respectively. Non-mechanized and obsolete HS reported the lowest efficiency and the highest environmental footprint, while fully mechanized systems reported the highest efficiency, the lowest number of accidents and the lowest stand damage. Cable yarders are the appropriate extraction technology in steep terrain, but they require a well-developed road network. Higher mechanization degree, improved quality of the road networks, knowledge transfer to practice and training of forest workers are some of the necessary measures to overcome the efficiency gaps in timber production in European mountain forests.     

Improving cross drain systems to minimize sediment delivery using GIS

A well developed network of roads must exist as a necessary infrastructure system in modern forestry to facilitate forest operations. But forest roads have the potential to disrupt the drainage characteristics of watersheds and lead to negative impacts on the environment with increased erosion and sediment yields. Numerous factors affect surface erosion of roads and sediment production potential; determining and ranking them could be a guide for management decisions to erosion control. In this study, the CULSED model (as an extension of ArcGIS) was used to estimate sediment delivery and the distribution of a road network, given the existing culverts. Using the model, some culverts were added to the road network around places with high sediment delivery in order to minimize it. After a correlation analysis and adjustment between sediment production and the factors, i.e., road width, road gradient, age of road and vegetation cover, the trend of changes in sediment delivery with model changes in the input was investigated with a sensitivity analysis of the model. The results show that adding new culverts to the road resulted in a significant reduction of sediment delivery. The most important factor affecting sediment delivery was road width, followed by road gradient, vegetation cover and age of road. Road width and gradient were positively correlated with sediment delivery, while vegetation cover and age of road were negatively correlated. The best model to show the relation between sediment delivery and road width as well as with road gradient was a linear model, for vegetation cover a cubic equation and for road age a power model. The results of sensitivity analysis showed that sediment delivery had the greatest sensitivity to changes of road width and was least sensitive to changes in the age of the road. This model can help to estimate sediment delivery with its spatial distribution, which can be used for optimization of cross drain systems and strategies of sediment control. Application of the model requires field trials to acquire the necessary input data. The reliability of our results is a function of the accuracy of inputs, especially digital elevation model.     

Decision-making for the selection of a best wood extraction method: An analytic network process approach

The importance of environmental and economical aspects in sustainable forest management (SFM), demands a continuing need for the application of efficient methods in this field. In this paper, we applied analytic network process (ANP) with benefits, opportunities, costs, and risks (BOCR) to evaluate four existing wood extraction methods (rubber-tired skidder, tracked skidder, cable logging and animal skidding) and select the best one based on SFM strategies in the Caspian (Hyrcanian) Forest, in northern Iran. The required data were obtained either from the previous studies or through pairwise comparisons conducted by a panel of forest engineering experts. Based on the BOCR subnetworks and their corresponding criteria, four alternatives were synthesized. ANP analysis indicated that the benefits and risks were more important in terms of decision-making, compared to the opportunities and costs. Finally, the alternative of ‘rubber-tired skidder’ was selected as the most suitable method for meeting SFM strategies. The decision framework proposed in this study offers a means for the reorganizing and planning of timber harvesting operations as an integral step toward SFM. By making minor adjustments for local conditions, this decision framework can be adapted for many other regions and countries.     

Comparison of the cost and energy efficiencies of present and future biomass supply systems for young dense forests

The objective was to study the effect of future harvesting and handling technologies on the cost and energy efficiency of supply chains for young dense thinnings. The system costs and energy requirements were modeled using type of stands, products delivered, and transport distances as variables. In total, 14 systems were analyzed, of which five represented future systems. The effects of increasing the payloads of off-road and road transportation of whole tree (WT) parts by 10%, 20%, and 30% were also analyzed. If boom-corridor thinning technologies, optimized bundle-harvesters, and load-compression devices are developed, on average, costs are reduced by 12–27% and 11–30% less energy is required when compared with present systems. For example, at an average harvested tree size of 22 dm³, the supply of WT using future technologies would reduce the cost by up to 15% and the energy requirements by 21%. These effects increase with reduced tree sizes and increased transportation distances. The effects of future technologies are especially significant for tree sizes below 30 dm³, representing a significant part of the potential that could be harvested annually in Sweden. Thus, there should be increased research and development of boom-corridor felling technology, bundle-harvesters, and load-compression devices.     

福建省国有林场手扶拖拉机标准参数的研究

本文针对福建省国有木场伐区木材生产状况。分析修建手扶拖拉机集材道的可行性。并根据东风12型手扶拖拉机机械性能。研究手扶拖拉机林道设计行车速度、最大纵坡、最小弯道半径等主要技术标准参数。     

Effects of aggregating forests, establishing forest road networks, and mechanization on operational efficiency and costs in a mountainous region in Japan

We investigated forest road networks and forestry operations before and after mechanization on aggregated forestry operation sites. We developed equations to estimate densities of road networks with av...     

城市道路网结构形式的特点分析

城市道路网结构形式是影响城市发展及城市交通的一个重要因素。通过对具有典型路网的城市进行研究，分析并总结了四种基本路网形式的特点，为城市路网形式的选择提供理论基础。由此提示在城市道路网规划中应重视对城市道路网合理结构形式的论证。     

福建林区林道等级确定方法的初步研究

通过分析林道等级与林道工程造价、木材运输成本和社会效益等之间关系。指出确定林道等级时,应在满足木材生产技术要求的前提下,力求综合费用最低,并给出具体确定方法。     

Optimal road spacing of cable yarding using a tower yarder in Southern Austria

Cable yarding systems are widely used in mountainous forests of Austria. The goal of this paper is to determine optimal road spacing (ORS) of yarding operations by tower yarder in Styria to help logging planners minimize logging costs. A total of 591 working cycles were used to develop the multiple regression model using stepwise method to predict yarding time per cycle. The production and cost in whole tree uphill yarding were 6.70 m³/PSH and 27.60 Euro/m³, respectively. The roading, yarding and installation cost per cubic meter were computed for different yarding distances and graphed as a function of road spacing. The minimum total cost and ORS were 42.88 Euro/m³ and 261 m, respectively for one-way yarding. For two-way yarding, the minimum estimated total cost, ORS and optimal road density would be 38.48 Euro/m³, 373 m and 26.8 m/ha, respectively. The results showed increasing harvested volume decreases ORS and that increased roading cost increases ORS. The load volume has a significant effect on ORS.     

The impact of road geometry,surface roughness and truck weight on operating speed of logging trucks

Improved transport planning and pricing is dependent on correct cycle times. The objective of this study was to quantify the effect of road curvature, surface roughness, gradient and truck weight on the operating speed of a conventional 60-tonne gross vehicle weight logging truck. The study used a 320-km test track consisting of both public and forest roads. The track was driven with various gross vehicle weights. Speed data was retrieved from the truck’s CAN-bus system and road data was measured with a profilograph. The key factors for operating speed were curvature and surface roughness, both of which were correlated to each other as well as partially captured by functional road class. Regression analysis quantified the individual effects of these factors as well as gradient, undulation and interactions with truck weight. A regression model is presented which explained 80% of the variation in operating speed. The results were consistent with previous studies, and the proposed models can be used to improve transport planning, cost estimation, operative route path selection and road investments.     

GIS-based decision support system for wood logistics

A wood logistics system was combined with a linear programming (LP) method utilizing GIS-based techniques on the platform of GIS soflware-ARC/INFO. The combined costs of road and off-road transport were taken as the objective function to find the least cost route and the optimal landing locations of wood transportation. Then transport costs and allowable wood volume of stands were calculated. An LP model was developed to allocate timber resources among mills in order to minimize the wood logistics costs from harvesting sites to mills. The parameters of the LP model, including the transport costs, allowable wood volume and wood orders, were written into a text file in MPS format which were then accessed by LINDO to solve the LP problem. The system is an effective tool to manage logistics, information and funds together in order to increase the speed of wood logistics and reduce the cost.The benefits and efficiency of mill cluster can be improved. The focal firm in the cluster can be competitive.     

Operational impacts to residual stands following ground-based skidding in Hyrcanian Forest, northern Iran

Hyrcanian (Caspian) Forest in northern Iran has a richness of biological diversity, with endemic and endangered species. The usage of ground-based skidding is well accepted practice for the extraction of timber from the forest, but this operation has tended to cause the greatest environmental problems. The aims of the study were to evaluate and comparison of operational impacts, residual stand damage, regeneration, and to quantify these effects such as: the extent of the damage, wounding patterns, size and distribution after logging operations that utilized two different methods: short-log and long-log. A Timberjack cable skidder was used and the study location was in the Kheyrud Forest. Post harvesting assessment of damage to the residual stand was compared along skid trail by 100% inventory method and also for the assessment of regeneration damage along winching strips. The results show that along winching strips the percentage of damage to the regeneration was 44% and 36%, while the tree damages along skid trails reached 2.3% and 4.1% in the short-log and long-log methods, respectively. The greatest average amount of damage to a bole occurred along the first 1 m up from the ground (97%) and also within 4 m of the skidder centerline (80%). These results show that the short-log method causes less damage to the residual stand than the long-log method. Tree location to skidder trail appears to have a significant effect on the number and height of scars on a tree. Well designed and constructed trails should be wide enough to allow wood extraction from the forest. Damage to the residual stand might be reduced by proper planning and training of logging crews.     

基于工程造价比较法的森林公园道路设计方案选优——以东莞市森林公园的园区道路建设为例

文章以东莞市4个森林公园的园区道路建设案例,采用数理统计的方法,分析了公开招投标项目中施工图预算的量价关系,阐述降低园区道路建设成本的科学方法,最后提出如何用工程造价比较法判断森林公园道路勘测设计的经济合理性。     

东北林区伐区林道合理配置的研究

运用木材采运成本最低的理论,结合东北林区资源、自然条件,科学的确定林道间距和配置形式、达到适宜的集材距离,健全和完善了伐区林道规划体系,提高了路网理论的应用价值。     

Spatially explicit assessment of forest road suitability for timber extraction and hauling in Switzerland

Efficient forest management, and wood production in particular, requires a forest road network of appropriate density and bearing capacity. The road network affects the choice of a suitable extraction method and the length of the transport route from the forest, while the road standard defines the truck type that can be used.

We evaluate the forest road network’s economic suitability for harvesting operations in the entire Swiss forest, an area of about 13,000 km² covering a range of topographies, based on the Swiss National Forest Inventory’s (NFI) forest road dataset. This dataset is based on information from an interview survey with the local forest services and includes all forest roads in Switzerland capable of carrying trucks. Extraction options and hauling routes are analysed together; thus, the entire logging process is examined.

Model results include maps of the most suitable extraction method; extraction costs; hauling costs; and a suitability map based on a combination of the results. While the larger part of the Swiss forest is classified as “suitable” for economic harvesting operations, significant portions also fall into the “limited suitability” and “not suitable” categories. Our analysis provides an objective, country-wide, spatially explicit assessment of timber accessibility. The resulting suitability map helps identify areas where timber harvesting is economic using the current forest road network, and where it is not. The model results can be used in road network planning and management, for example, by comparing road-network re-design scenarios, and compared to the spatial distribution of available wood volume.