Optimization of Road Spacing for Log Length Shovel Logging on Gentle Terrain

Abstract

Shovel logging has become a popular logging system in the western United States due to its high productivity. Its low ground pressure and single pass, often on a matt of limbs result in little ground disturbance. Despite this increasing popularity, there have been few operational studies of shovel logging. This paper describes the optimal road spacing problem for shovel logging using a serpentine pattern on gentle terrain. A mathematical model for shovel logging is presented for two cases (1) to minimize the sum of shovel yarding costs plus road costs from the landowner’s point of view and(2) to maximize profits from the point of view of a logging contractor. For the operating conditions assumed, the optimal shovel yarding distance is four swings when shovel yarding plus roads costs are minimized and three swings when logging contractor profit is maximized. For the example data, the model results demonstrate the flexibility of shovel logging in that there is little difference between total road construction plus skidding cost from the optimal number of swings to as many as six swings. Sensitivity analysis was performed on road cost and volume per ha and support the stability of the solution with the minimum logging cost occurring at four swings with just a small difference for as many as six swings over a range of road construction and volume removals.