This section provides
some basic information and spreadsheets for costing as it
applies to harvesting equipment and systems. The following
topics are covered;
Operating Costs for Logging Equipment
A very common
method of determining a specific logging machine cost is to
use a Machine Costing Spreadsheet . This
method is very useful for predicting approximate hourly costs
of a machine, or to make a cost comparison between two machines.
requires you to enter basic machine costing values, which
it uses to establish the (a) fixed operating cost, (b) the
running cost as well as the (c) labor cost for the machine.
The resulting cost estimate is per Scheduled Machine Hour
(SMH), that is, for every hour the machine is scheduled to
work and it includes down-time. Remember: with a spreadsheet
model, the result is only as accurate as the inputs!
Go to Machine Costing Spreadsheet
Hourly cost per
Productive Machine Hour (PMH) will be higher, and can be obtained
by diving the $/SMH by the utilization rate. This would reflect
the cost if the machine is compensated only when it is working.
Also, the actual costs incurred vary not only with the final
true costs associated with the spreadsheet input parameters,
but also with state and federal tax laws.
The basic approach
to harvest system costing is to carefully calculate out the
Hourly Machine Cost of each piece of equipment in the system
and add them up. In addition, include other costs such as
overhead, workshop, storage, service vehicles etc. It is also
common to increase the final sum with an indirect logging
cost (typically 10%) to account for miscellaneous and unscheduled
Go to System
Machine or System Productivity
only varies greatly with the logging machine or system chosen,
but also with stand and site characteristics of the harvest
area. The easiest way to get an approximate idea of productivity
is to find out what the system currently delivers on an average
day or week. Dividing this by the number of scheduled hours
provides an indicative productivity (tons / SMH). Another
potentially useful source of information is published productivity
studies. However, the most accurate way of obtaining reliable
productivity information for a given machine or system at
a given site is to carry out a time and motion study.
have carried out production studies on harvesting systems
often produce a ‘productivity model’. This can
be a spread sheet or a computer program that will help predict
productivity based on both stand and terrain parameters. One
should be careful about using ‘productivity models’,
they are based on a given system under given conditions – but they can be very useful for comparisons.
accurate logging cost for a given harvesting operation can
be difficult. There are two principle factors that must be
Total cost of running a machine or system ($)
Production: Production of the machine or system
the cost by the production, we arrive at a unit cost of harvesting
($/ton). There are two main methods to determine logging cost,
the ‘Cash Flow’ and the ‘Machine Rate’ methods.
‘Cash flow’ method uses loggers past data to establish a logging rate.
This is most appropriate for a harvesting contractor. He or
she simply adds up all the business related costs for the
last year, as well as adds up all the tons of timber delivered.
By dividing the two, we have the actual average logging rate
for the last year ($/ton).
This method does
have its disadvantages. It does a very poor job of spreading
out larger costs, such as equipment purchases or major equipment
repairs (unless all equipment is leased). These large individual
costs can be replaced with either an appropriate monthly depreciation
or a monthly payment schedule cost. Also, forest company personnel
should not have access to this information as it typically
is a breach of anti-trust laws.
Machine rate method
combines two of our previously discussed sections (1) calculating
hourly system costs as well as (2) estimating productivity,
to predict a harvest rate. Dividing the system cost ($/SMH)
by the predicted productivity (tons/SMH) will provide the
harvesting rate ($/ton).
The advantage is
that the Machine Rate Method is very ‘transparent’
– it is easy to see what values have been placed in
the spreadsheet and it is possible for multi-parties to work
on it together. The disadvantage is that all values are estimates,
and again the output of the model is only as good as its inputs.
Harvest System Costing
By combining system,
stand, terrain, productivity and cost information from numerous
studies, it is possible to create a more complete harvest
costing model. These ‘combination’ models predict
system costs and productivity, and therefore the expected
logging rate as well. Three models are made available on this
website. The first is the Auburn Harvester Analyzer. It was
produced in 19XX for a Hydro-Ax 511 feller-buncher, CAT 518
skidder and a 210 Prentice loader system. The original spreadsheet
calculated all volumes in Cords. This spreadsheet was converted
into tons (Rien Visser, Virginia Tech) and is also available.
- Auburn Harvester
Analyzer spreadsheet (cords)
- Auburn Harvester Analyzer spreadsheet (tons)
Hank Sloan, a long
term Forest Service Logging Engineer, used all his experience
and information (as well as programming skills) to create
the Logging Cost Calculator. Mr. Sloan has made his model
freely available on this Website, but does ask all commercial
users to consider making a donation to the Tom (Doc) Walbridge
Sloan’s Logging Cost Calculator
The final model
presented on this Website was developed by a graduate student
at Virginia Tech, Kieran McDonagh. It was developed in the
Stella software environment and models the flow of timber
through the system. It also takes into account the trucking
capabilities of the harvest system.
Harvest System Allocation Model
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