Abstract
This article reports on track-monitoring and analyzing machine clearances during wood forwarding across seasons and weather, using ultrasonic distance sensors in combination with time-stamped GPS xy locations, at 10 sec intervals. The resulting data, obtained from 54 harvesting blocks, were analyzed by machine type (two wood forwarders and one grapple skidder), stand type (softwood plantation versus natural hardwood stands), month, slope, cartographic depth-to-water (DTW) classes, number of passes along track, and machine speed. For the most part, clearances were highly variable, due to passing over stumps, rocks, harvest slash, brushmats, ruts, and snow cover when present. This variability was on average greater for the lighter-weight wood forwarders than for the heavier-weight skidder, with the former mostly moving along equally spaced lines on brushmats, while the paths of the latter spread away from central wood-landing sites. In terms of trends, machines moved 1) more slowly on wet ground, 2) faster during returning than forwarding, and 3) fastest along wood-landing roads, as to be expected. Low clearances were most notable during winter on snow-covered ground, and on non-frozen shallow DTW and wet multiple-pass ground. During dry weather conditions, clearances also increased from low-pass tracks to multi-pass tracks due to repeat soil compaction of broadened tracks. These results are presented block-by-block and by machine type. Each block-based clearance frequency pattern was quantified through regression analysis and using a gamma probability distribution function.
Highlights
IntroductionIn this regard, improper timing by season and weather can lead to substantive soil compression and rutting across and along flow channels, on ridge tops, through depressions with moist to wet soils
The normalized clearance data were compiled into a single spreadsheet to enable the machine clearance analysis in relation to: 1) month of harvesting, 2) weather-induced soil wetness, 3) machine speed, 4) machine load, 5) back and forth track direction, 6) number of passes, 7) machine type, 8) harvesting type, 9) slope, and 10) DTW
This was done for each harvest block to allow for detailed per block analyses in terms of 1) histogram and frequency distribution assessment, and 2) to determine how the clearance data were affected by pass number, machine speed, and by DTW classes
Summary
In this regard, improper timing by season and weather can lead to substantive soil compression and rutting across and along flow channels, on ridge tops, through depressions with moist to wet soils. This article focuses on monitoring and examining machine-to-ground clearances in relation to number of passes, wood forwarding machine speed, and dry to wet ground conditions involving 54 harvest blocks in New Brunswick, Canada. For this purpose, two forwarders (John Deere 1110E and 1510E) and one grapple skidder (Tigercat 635D) were equipped with ultrasonic distance sensors, and GPS data loggers. The dry to wet variations in ground conditions were related to changing seasons and weather, and to topography across each harvest block as revealed by way of the metric cartographic depth-to-water index (Murphy et al, 2011; White et al, 2012)
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