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    Author(s): R.H. Twito; R.J. McGaughey; S.E. Reutebuch
    Date: 1988
    Source: Gen. Tech. Rep. PNW-GTR-215. Portland, OR: U.S Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p
    Publication Series: General Technical Report (GTR)
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (1.3 MB)


    PLANS, a software package for integrated timber-harvest planning, uses digital terrain models to provide the topographic data needed to fit harvest and transportation designs to specific terrain. SKYTOWER and SKYMOBILE are integral programs in the PLANS package and are used to design the timber-harvest units for skyline systems. SKYTOWER determines skyline payloads and spans for towers operating in fan-shaped settings from large central landings. The maximum yarding limit for each profile in groups of 18 circularly arranged yarding corridors is displayed after a landing is digitized on the digital terrain model. This unit can be modified to meet the planning needs. SKYMOBILE is similar except it is used for mobile yarders operating in parallel settings and permits several adjoining skyline spans to be designed on the same profile. Both use similar algorithms that permit quick solutions for either the longest span a designated payload can be yarded over or the largest payload that can be yarded over a designated span. Both program algorithms provide convenient ways to adjust the design and to locate '.' and mark the final design on the topographic map. The algorithms for these skyline solutions, which are approximations of exact catenary solutions for cables, are explained as are limitations of the methods used. Guides giving detailed operating instructions for the programs are available from the authors.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
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    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Twito, R.H.; McGaughey, R.J.; Reutebuch, S.E. 1988. The SKYTOWER and SKYMOBILE programs for locating and designing skyline harvest units. Gen. Tech. Rep. PNW-GTR-215. Portland, OR: U.S Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p


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    Computer programs/programing, logging operations analysis/design, timber harvest planning, road building (forest/logging)

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