Metric measurements for optimization of forest road network alternatives in GIS-based programs

Abstract

An efficient forest road network can increase accessibility to entire forest lands and decrease construction and maintenance costs. In this study, first cost layer for road construction in the semi-mountainous Hyrcanian forest was developed by overlaying thematic layers of slope steepness, soil depth, and proximity to hydrograph network in geographical information system (GIS). Analytical network process (ANP) was used to determine the importance of the layers. Nine road network alternatives were designed on cost layer using PEGGER and then the efficiency of each alternative was evaluated according to the metric of road passage percentage from cost classes. Technical assessment was done by analyzing metrics of overlaps, opened area, and corrected ton-km. The optimum forest road network alternative was selected by pairwise comparison of alternatives with respect to metrics. Based on our findings, we strongly recommend the use of alternative 8 whenever possible, because the construction cost, corrected ton-km, and overlaps were lower, and the opened area was higher than those of the other alternatives.