Backgrounds of the cost calculations

The cost calculation methodology

Cost calculation is one of the most important bases at machine and technology choices, and enables process optimization. The "Cost Calculation" tool was developed by the researchers of the Slovenian Forestry Institute and is the result of multiannual research in the field of forest work standardization and the study and monitoring of the costs of forestry machinery. The WoodChainManager web tool addresses most of the machines used in forestry in Slovenia. The default values of calculation attributes can be adjusted by each user according to his own machine or needs.

Basis

Before implementing the software solutions, several methods for cost calculations (including FAO, KWF ...) were examined and decision on the method used in Slovenia for calculating costs in the Catalog of Agricultural and Forestry Machinery Costs (Dolenšek, 2008) was made. The latter is based on the methodologies of comparable machine costs catalogs issued by Kuratorium für Technik und Bauwesen in der Landwirtschaft e.V. (KTBL) (Germany), Österreichisches Kuratorium für Landtechnik und Landentwicklung - ÖKL (Austria) and Agroscope Tönikön (Switzerland).

The harvesting system is the basic starting point for the "Cost Calculation" tool, which calculates costs and visualises (describes() the individual harvesting system. When using a web-based tool, it is important for the user to have a continuous overview of processes in the harversting system. The user independently determines which processes will be performed (cutting, delimbing, cross-cutting, chipping, skidding / transporting) and the location where these processes will be carried out (Forest stand, Skid Trail, Skid Road, Forest Road...). The WoodChainManager automatically offers a set of machines that can perform selected operations at desired locations. In operations that also predict movements along the roads (skidding / transport), the location where the transport will end shall also be selected (Skid Road, Forest Road, End User). The web-based algorithm uses logical controls that prevent the user to choose a harversting system that is impossible. In doing so, the user can choose between several different machines and related accessories such as different types and versions of tractor attachments (winches, forest trailers ...) and tractor accessories (safety cabin, wheel chains, etc.). WoodChainManager currently provides the following groups of machines:

Chainsaws (classical, electric, onehanded),

Safety gear and cutting equipment,

Mobile winch with chainsaw,

Tractors and skidders,

Equipment for tractors (wheel chains, cabine protection..),

Winches (internal, three-point attachment) and which equipement (Radio remote controls, Overturn alert, Pulley..),

Standard log grips (three-point attachment),

Small caterpillar for skidding,

Forest trailers,

Harvesters,

Forwarders,

Chippers, Log splitters, Firewood processors,

Semi-Trucks with crane for roundwood and bulk load,

Cable crane yarders.

Key terms

For the common understanding, the meaning of the professional terms used, which define the calculation items, is explained below:

The described parameters are input data for calculating the material costs of machines. In addition to these "Cost Calculation" tools, they also include:

Methodology

The following table shows the equations used to calculate costs using the WoodChainManager tool

 

ParameterSighUnit of measurementIndicative and derived values used
Purchase value PV EUR The average value of a new machine in € on EU market.
Engine power output EP kW  
Depreciation period DR year /
Life span LR hour /
Annual use AU hour/year Estimated average use of certain machine type.
Maintenance factor Mr   0.07 - 0.15
Interests on invested capital DRrate % 6
Fuel price Fprice EUR / l The prices of fuel are updated twice a month.
Variable cost of fuels and lubricants Lr % 10
Engine load Ur   0.4 - 0.7
Average fuel consumption Fcons liter / kWh 0.33
Number of workers n   1
Productivity P hourly 0 - 100
Fixed machine costs Cfix EUR / hour ((PV / DR) + DRrate * PV) / AU
Maintenance costs Cmaint EUR / uro Mr * PV / LR
Cost of fuels and lubricants Cfuel EUR / hour (100% + Lr) * Ur * (Fcons * EP) * Fprice
Variable machine cost Cvar EUR / hour Cmaint + Cfuel
Labor cost Cwork EUR / hour 12 * n
Total costs per hour Csum EUR / hour Cfix + Cvar + Cwork
Total costs per unit of product Csum EUR / unit of product Csum / P

Cost calculations

The user of the web tool can independently select processes and machines, thus composing his own harvesting system for which the application automaticaly calculates the costs. Using different machines the user is able to examine the impact of different machine selection on the total cost of harvesting system and thus optimize their own business process. The tool has built-in logical controls that prevent the user to choose a harversting system that is impossible.

We invite you to test the tool for calculating costs and visualizing the harvesting systems by yourself. If you are using the tool for the first time, it is advisable to check the "Content, Basis and Cost Calculation methodology" page before using it. In order to understand all the proffesional terms and methodology of the calculation. In addition, selected examples of harvesting systems and interactive user instructions are presented.