Retroactive comparison of operator-designed and computer-generated skid-trail networks on steep terrain

Aim of the study: Quantify potential economic benefits of implementing computer-generated skid-trail networks over the traditional operator-designed skid-trail networks on steep terrain ground-based forest operations.Area of study: A 132-ha harvest operation conducted at the University of Kentucky’s Robinson Forest in eastern Kentucky, USA.Materials and methods: We compared computer-generated skid-trail network with an operator-designed network for a 132-ha harvest. Using equipment mounted GPS data and a digital elevation model (DEM), we identified the original operator-designed skid-trail network. Pre-harvest conditions were replicated by re-contouring terrain slopes over skid-trails to simulate the natural topography and by spatially distributing the harvestable volume based on pre-harvest inventories and timber harvest records. An optimized skid-trail network was designed using these pre-harvest conditions and compared to the original, operator-designed network.Main results: The computer-generated network length was slightly longer than the operator-designed network (53.7 km vs. 51.7 km). This also resulted in a slightly longer average skidding distance (0.71 km vs. 0.66 km) and higher total harvesting costs (5.1 $ ton-1 vs. 4.8 $ ton-1). However, skidding costs of the computer-generated network were slightly lower (4.2 $ ton-1 vs. 4.3 $ ton-1). When comparing only major skid-trails, those with ≥ 20 machine passes, the computer-generated skid-trail network was 28% shorter than the operator network (9.4 km vs. 13.1 km). Research highlight: This assessment offers evidence that computer-generated networks could be used to generate efficient skid-trails, help determine skidding costs, and assess further potential economic and environmental benefits.Key words: timber harvesting; forest operations; network optimization; soil disturbances; cost minimization