Volume 2, numéro 1, july 1990

EN :

A terrain evaluation model, utilizing a geographic information system, has been developed as a tool for planning large-scale industrial timber harvesting operations. The model combines terrain descriptions with machine operating criteria to produce maps delineating operable areas. The integration of the model with a harvest planning decision support system is discussed and an example is presented.

EN :

This paper describes a high-density path network in a steep mountain area which supports intensive, high quality forestry in Osaka, Japan. The network, which may be likened to a capillary vessel system, makes it possible to: undertake intensive treatment of forests; effect a selective harvest of small, scattered product volumes; change the harvesting method from cable logging (which requires greater worker skill and results in high costs) to one in which products are removed from the stump area by grapple boom cranes located on roads. This network consists of a series of 2.0m wide paths which run parallel to the contour lines and a steep (but very solid) main road (2.5m wide) connecting the paths. The former are branch lines (rib paths) used primarily for extraction and the latter (which is paved with concrete) is the main line (backbone) used for access to the branch lines. In this network, the maximum gradient is 30%, the maximum height of embankment is 1.4 m, the minimum turning radius is 6 m, road density is 222.94 m/ha, correction-factor of shape V = 1.421, correction factor of real skidding distance Ô = 1.215, and the development percentage is 77.9%. Data shows that the correction factors approach 1.0 as the road density is increased, even in mountainous landforms of the type described.

EN :

This study assesses changes in soil dry bulk density (dry unit weight), and evaluates soil disturbance associated with wide-tire skidder traffic on five Vancouver Island forest soils. In general, soil bulk densities increased with increasing skidder traffic; the effect was more pronounced at higher soil water contents. The results did not vary dramatically from site to site. Soil disturbance, in the form of rutting, and exposure of mineral soil increased with increasing traffic and was generally more pronounced under moist soil conditions. The compactive effect of the wide-tire skidder is at the lower end of the range of compactive effects reported for ground-based yarding equipment, but is still expected to have a negative effect on seedling height growth.

EN :

Forestry transport expenditures in Australia include both the costs of owning and operating logtrucks, and the costs of constructing and maintaining many kilometres of logging roads. Therefore,improving transport efficiency requires consideration of both road and truck related factors. However, analysis of these factors involves many complex interacting variables. A computer simulation model, TRUCKSIM, has been developed to assist in these analyses by predicting the effects of both road and alternative vehicle specification on transport performance. A description of the model and it's supporting programs is presented, together with a discussion of it's limitations and examples of it's use in evaluating alternative truck and road specifications.

EN :

Two Norwegian cutting instructors have been used as models for demonstration of "correct" and "poor" working postures in motor-manual cutting. This enabled estimation of the intervertebral disc compression forces at L5/Sl-level. The results/when related to defined lifting hazard levels shows that the compressive forces are greater in all "poor" postures compared with corresponding "correct" postures. Furthermore, relating to the lifting hazard levels, it becomes obvious that even correct working techniques in the felling and bunching sequences entails hazardous compressive forces in the lumbar column. This is probably one of the main causes of the high incidence of lower back injuries among loggers. Training courses for better technique and adminstrative or engineering controls to eliminate the peak loads are still needed in forestry.