Ola Lindroos

Swedish University of Agricultural Sciences | SLU · Department of Forest Biomaterials and Technology

Forestry cranes are essential machines used in Scandinavian forest operations. Despite their importance, their design has remained unchanged for decades, raising environmental concerns due to their large size, weight, and energy consumption. Lack of analysis on how the cranes move when performing their work is one of the main reasons why their desi...

Restoration of degraded habitat is frequently used in ecological compensation. However, ecological restoration suffers from innate problems of long delivery times of features shown to be good proxies for biodiversity, e.g., large dead trees. We tested a possible way to circumvent this problem; the translocation of hard-to-come deadwood substrates f...

Designing an optimal machine trail network is a complex locational problem that requires an understanding of different machines’ operations and terrain features as well as the trade-offs between various objectives. With the overall goal to minimize the operational costs of the logging operation, this paper proposes a mathematical optimization model...

Extraction of timber is expensive, energy intensive, and potentially damaging to the forest soil. Machine development aims to mitigate risks for environmental impact and decrease energy consumption while maintaining or increasing cost efficiency. Development of rubber-tracked forwarders have gained renewed interest, partly due to climate change lea...

This article presents a study on the world’s first unmanned machine designed for autonomous forestry operations. In response to the challenges associated with traditional forestry operations, we developed a platform equipped with essential hardware components necessary for performing autonomous forwarding tasks. Through the use of computer vision,...

Most forest operations are complex problems that require the weights of relevant criteria – representing trade-offs between various economic, ecological, and social aspects of the problem – to be defined. Usually this is done by using multicriteria weighting method(s) in a group (participatory) context in order to include different opinions and to...

There is a need to decrease the costs of cut-to-length operations. The harwarder, a one-machine system with the potential to reduce the costs, has been compared to the two-machine system (TMS) at the stand and regional levels but not at the national level, which is important as basis for decision to implement. The objective was therefore to analyze...

The mechanization of roundwood harvesting in Sweden has historically cut costs rapidly. However, machinery and work methods have conceptually stayed the same since the introduction of the single-grip harvester. Current trends indicate that the next major wave of development will be based on automation, and that teleoperation is a step in this direc...

There are many factors to consider when deciding which technologies to use in forest operations and how to plan their use. One important factor is the overall cost when choosing between the established two-machine system (TMS) with a harvester and a forwarder, and a one-machine system with a harwarder in final fellings. Such considerations can be d...

Although most mechanized forestry work relies heavily on cranes for handling logs along the supply chain, there has been little research on how to improve cranes design. In addition, the available research has mainly focused on improving current designs, so there is a lack of application of modern methods for designing cranes with improved efficien...

In many parts of the world, contractors account for the main share of harvesting work. Harvesting is characterized by innate complexity and volatility, and this can affect contractors’ workflow and ultimately their profitability. Thus, there is certainly a need for flexibility in harvesting service provision and procedures, but our current knowledg...

Technological development gives forest companies opportunities to maintain competitiveness in the highly cost-sensitive market for forest products. However, no previous studies have examined the technological development decisions made by forest companies or the support tools used when making them. We therefore aimed to describe and analyze 1) the...

The extensive outsourcing of forest harvesting operations means that the operational performance of contractors has an immense impact on the forest industry supply chain. This study describes perceived drivers and obstacles for strong performance in harvesting service based on semi-structured interviews with four production supervisors and eight co...

Translocation of dead wood is a novel method for ecological compensation and restoration that could, potentially, provide a new important tool for biodiversity conservation. With this method, substrates that normally have long delivery times are instantly created in a compensation area, and ideally many of the associated dead wood dwelling organism...

Despite the large biomass potential, current management practices for roadside verges (ditch backslopes,foreslopes and bottoms, possible parking lots and other lateral land) consist of regularly cutting the vegetation manually with motorized brush saws or flail mowers and leaving it to rot in situ. Regular vegetation clearing is crucial for safety...

Modern forest harvesters automatically collect large amounts of standardized work-related data. Statistical machine learning methods enable detailed analyses of large databases from wood harvesting operations. In the present study, gradient boosted machine (GBM), support vector machine (SVM) and ordinary least square (OLS) regression were implement...

Operators of mobile machines within forestry work long hours in seated postures while being exposed to whole-body vibration (WBV) that is associated with pain in the lower back and neck. Still, little is known about the contribution from postural loads. In this study postural loads and shock-type WBV exposure on drivers operating a forwarder during...

Quad bikes are light-weight vehicles which are used for transportation of personnel, equipment, and material in forestry operations such as planning, logging, planting, and fire-fighting. With increased quad bike usage, serious injuries have become an increasing concern. The most common forms of severe incidents occur when a quad bike loses stabili...

As various methods for precision inventories, including light detection and ranging (LiDAR), are becoming increasingly common in forestry, planning at the individual-tree level is becoming more viable. In this study, we present a method for finding the optimal thinning times for individual trees from an economic perspective. The method utilizes a f...

Worldwide, the number of quad bike-related injuries and fatalities has increased over the last 30 years and, although quad bike safety has become increasingly important over the last decade, greater understanding of the risks associated with these vehicles is required. This study aimed to improve understanding of the interrelationships between risk...

Performing work for extended periods of time while using the lowest amount of resources is an important aspect for productivity in many industries. In forestry, the productivity of a forwarder is seen as the volume of material it can extract to a roadside landing in a certain amount of time, where the process of loading and unloading logs represent...

Farm tractor + trailers play a key role in wood transportation after forests are logged. Despite of the fact that a forwarder is a forestry vehicle that carries felled logs for shorter distances off the ground, tractors are still used in some forest areas of the world, such as the Hyrcanian forest in northern Iran. This study was conducted to inves...

Size and spatial distribution of trees are important for forest stand growth, but the extent to which it matters in thinning operations, in terms of wood production and stand economy, has rarely been documented. Here we investigate how the choice of spatial evenness and tree-size distribution of residual trees impacts wood production and stand econ...

Although being rather similar in appearance, forwarders have gone through substantial development during the more than half a century they have been used in forestry. The aim was to describe the development in Sweden, by a combination of historical narratives and data. The latter consists of technical parameters of forwarders sold on the Swedish ma...

Decision making in forestry is very complex and requires consideration of trade-offs among economic, environmental, and social criteria. Different multi-criteria decision analysis (MCDA) methods have been developed for structuring and exploring the decision-making process of such problems. Although MCDA methods are often used for forest management...

Ground-based mechanized forestry requires the traversal of terrain by heavy machines. The routes they take are often called machine trails, and are created by removing trees from the trail and placing the logs outside it. Designing an optimal machine trail network is a complex locational problem that requires understanding how forestry machines can...

In forest operations, the interface between forest companies and harvesting contractors is of special importance, considering that it is the first link in the forest industry's supply chains. Supply operations account for a significant share of the final costs of wood products (up to 50%). This study investigates the effect of customer-contractor a...

Timber harvesting operations vary greatly around the world, as do the adaptations of technology to the complex, locally variable conditions. Similarly, technological innovations occur as a response to a large number of different situations. This review examines the three main drivers considered to generate substantial technological change in mechan...

Study design: Human volunteers were exposed experimentally to single-sided mechanical shocks (SSMS) and double-sided mechanical shocks (DSMS) while seated. Objective: To describe and contrast seated postural reactions due to SSMS or DSMS in healthy male adults. Summary of background data: Mechanical shocks to the body, caused when driving on i...

In a global bioeconomy, benchmarking costs is essential in the evaluation of current forest harvesting systems and addressing decisions on the most efficient supply chains for available forest resources. Benchmarking cost rates in forestry is challenging, due to a lack of harmonized terminology and difficulties in collecting information on comparab...

Automatic collection of forwarding follow-up data has recently become possible. The objective of this study was to obtain representative values of fuel consumption for large forwarders in final felling operations. Since fuel consumption is dependent on time consumption, speed, and total driven distance, these variables were also included in the stu...

Competition for woody biomass between material and energy uses is expected to further increase in the future, due to the limited availability of forest resources and increasing demand of wood for material and bioenergy. Currently, methodological approaches for modeling wood production and delivery costs from forest to industrial gates are missing....

The efficiency of cable-based yarding systems has been studied extensively, resulting in numerous work productivity models (i.e. models predicting the ratio between output and time). Productivity models are used in both research and operations management, but are laborious to develop. Efficient use of existing models is essential, but there is a la...

In recent years, concern has been raised that the trend of continuous productivity improvements of forest harvesting has stagnated and even declined in the Nordics. This selective literature review therefore examines human factors research with regard to the performance of the harvesting system, and outlines how human factors research can stimulate...

Exposure to whole body vibration (WBV) is a major concern in mechanized forestry work because its adverse effects may become exacerbated by repetitive hand and arm movements, and non-neutral body postures. Moreover, shock-type vibrations have recently been suggested as a possible agent behind pains in the neck and shoulders of forest machine operat...

Recent developments in on-board technology have enabled automatic collection of follow-up data on forwarder work. The objective of this study was to exploit this possibility to obtain highly representative information on time consumption of specific work elements (including overlapping crane work and driving), with one load as unit of observation,...

In mechanized forestry, much of the work is conducted by use of cranes, and recovering potential energy is a possible method to reduce energy consumption when using cranes for lift work. The objective of this study was to evaluate the capacity of a new »Energy-efficient hydraulic lift cylinder« (EHLC), which has a secondary cylinder built into its...

In forest harvesting, operators must visually monitor the terrain, machinery, the stand and the trees they are cutting in order to plan, evaluate and adjust their tasks. To exploit increasing opportunities to automate these tasks and create decision support systems it is essential to understand not only what forestry workers do, but also what they...

Driving on irregular terrain will expose the driver to sideways mechanical shocks or perturbations that may cause musculoskeletal problems. How a cognitive task, imposed on the driver, affects seated postural reactions during perturbations is unknown. The aim of the present study was to investigate seated postural reactions in the neck and trunk am...

Driving on irregular terrain will expose the driver to sideways mechanical shocks or perturbations that may cause musculoskeletal problems. How a cognitive task, imposed on the driver, affects seated postural reactions during perturbations is unknown. The aim of the present study was to investigate seated postural reactions in the neck and trunk am...

Performance of harvesting operations is vital for wood supply chains to enable delivery of the right product to the right market at the right price. Consequently, the performance of harvesting contractors has been the topic of many studies over the years, but few of these have investigated the critical issue of whether contractor performance is in...

Modern harvesters are technologically sophisticated, with many useful features such as the ability to automatically measure stem diameters and lengths. This information is processed in real time to support value optimization when cutting stems into logs. It can also be transferred from the harvesters to centralized systems and used for wood supply...

Modern computerization facilitates data-gathering from forest machines, and offers new opportunities to develop models for predicting productivity in forest harvest operations. In this study, we analyze the productivity of cut-to-length harvesting and forwarding in thinning and final felling using a routinely recorded follow-up dataset. The data or...

In mechanized ground-based forestry, machines operate on rough soils that, ideally, should remain unafected by the operation. This implies small (that is, light) loads and careful driving are required. However, economical rationality implies large loads and high speeds. Recently, the concept of adding a trailer to a conventional forwarder has been...

The 1980s were very active years for the world’s forest harvesting industry. Many new machines and logging systems were being introduced, particularly in North America and Scandinavia. However, the forest engineering community had no dedicated scientific journal in which to report the results of their research, and to disseminate these findings bac...

This literature review focuses on quantified or qualified impacts of forest biomass extraction with varying harvest intensity on environmental sustainability. The focus is on soil carbon, nutrient balances, water quality, biodiversity as well as on forest productivity in the following management cycle. Studies from Europe were selected with the pur...

On Nordic clearcuts, today's tree planting machines produce high-quality but costly regenerations. Much of this high cost is attributable to the planting machines' low productivity. One promising way of raising productivity is to lessen the time spent manually reloading seedlings onto the carousels of crane-mounted planting devices. Using MagMat, a...

Accurate vehicle localization in forest environments is still an unresolved problem. Global navigation satellite systems (GNSS) have well known limitations in dense forest, and have to be combined with for instance laser based SLAM algorithms to provide satisfying accuracy. Such algorithms typically require accurate detection of trees, and estimati...

Forwarding has been carried out for 50 years, but much is still unknown about this work. Its complexity comes from both stand features and essential decision-making. Forwarding time consumption is influenced by e.g. log concentrations and number of assortments. Traditionally, focus has been on the total log concentration (TLC), referring to all log...

Wheel slip may increase the risk for wheel rutting and tear up ground vegetation and superficial roots and thereby decreasing the bearing capacity of the ground, but also reducing the growth of nearby standing forest trees. With increased slip, more energy is consumed for making wheel ruts in the ground, with increased fuel consumption as a result....

In the mechanized cut-to-length system, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs in the load space of the transporting machine as they are cut. Two approaches for this integration of work tasks are available: te...

In conventional mechanized cut-to-length systems, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs directly into the load spaces of transporting machines as they are cut. Such integrated loading could result in cost red...

Even though stumpwood may become a significant part of the future fuel mix for combined heat and power plants in Sweden, the harvesting of stumps after regeneration felling is still only performed on a trial basis. Results from time studies on two, 23 tonne, excavators fitted for stump lifting, together with follow-up data on stump lifting and forw...

Nacrtak Human operators are key determinants of the performance of most production systems, so individual performance is of intrinsic interest when evaluating current and proposed sys-tems for forest operations. Such evaluations can be useful for diverse purposes, for instance, planning, incentive-setting, control and costing. Hence, various evalua...

Autonomous navigation in forest terrain, where operation paths are rarely straight or flat and obstacles are common, is challenging. This paper evaluates a system designed to autonomously follow previously demonstrated paths in a forest environment without loading/unloading timber, a pre-step in the development of fully autonomous forwarders. The s...

The measure of performance in forest harvesting is an essential prerequisite for planning and improving forest operations. Traditionally the focus has been towards machine-related performance measures such as production of wood per time unit. However, in today's increasingly complex wood supply networks, the demand of a more complex analysis of per...

Firewood is society’s oldest source of household energy and is still extensively used around the world. However, little is known about firewood usage in technologically advanced countries with high energy consumption. Some key issues include quantities of firewood currently used and future trends, as well as the influence of this usage on available...

This study evaluated the costs, CO2 emissions, and energy balances associated with three potential systems for recovering roadside slash in British Columbia, Canada, in which the biomass is transported as slash, hog fuel, or bundles. Costs, CO2 emissions, and energy balances of all three systems showed strong dependence on transportation distance a...

In conventional mechanized cut-to-length systems, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs directly into the load spaces of transporting machines as they are cut. Such integrated loading could result in cost red...

Today's crane-mounted planting heads plant seedlings with biologically similar or better results than operational manual planting. However, the total cost of mechanized tree planting in southern Sweden must decrease at least 25% to compete economically with manual planting. Although seedlings packed in machine-specific packaging increase the produc...

Half of all Swedish forests are owned by private individuals, and at least 215,000 people work in these privately owned forest holdings. However, only lethal accidents are systematically monitored among self-employed forest workers. Therefore, data from the registries of the Swedish Work Environment Authority, the Labor Insurance Organization and t...

Nordfjell, T. 2010. Productivity of a prototype truck-mounted logging residue bundler and a road-side bundling system. Silva Fennica 44(3): 547–559. When recovering logging residues (LR) for bioenergy its density should be increased before road transport, otherwise a low proportion of the trucks' load capacity will be used. One way this can be curr...