The HIGHLEAD program: locating and designing highlead harvest units by using digital terrain models.

Abstract

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. HIGHLEAD, an integral program in the PLANS package, is used to design the timber-harvest units to be yarded by highlead systems. It solves for the yarding limits of direct mainline pull to the top of the tower by assuming that the angle of pull must be equal to or greater than the slope of the ground. The ground is sampled through a system of 18 uniformly spaced corridor profiles that radiate from user-selected landing locations and that are extrapolated from the digital terrain model. HIGHLEAD permits the planner to reduce the yarding coverage by shortening yarding distance on individual corridors or by deleting portions of the yarding circle. Conversely, the planner can try to extend the yarding distance on individual corridors by tightlining. The algorithm for tightlining is explained as are limitations of the analysis and interpretations on the maximum, safe log load for highlead systems. A guide giving detailed operating instructions for the program is available from the authors.

Citation

Twito, R.H.; Reutebuch, S.E.; McGaughey, R.J. 1988. The HIGHLEAD program: locating and designing highlead harvest units by using digital terrain models. Gen. Tech. Rep. PNW-GTR-206. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 21 p