Planning Forest Road Alignment Using a Shortest Path Algorithm and Geographic Information System

The main purpose of the current study was to design less costly forest roads using cost zoning map. For this purpose, the most important effective factors on cost of forest road construction were weighted using the Analytical Hierarchy Process (AHP). Five factors, terrain slope, hydrology, geology formations, soil texture and road slope, were weighted using the AHP. The cost zoning map was developed after weighting the supposed factors and overlay their corresponding map in ESRI Arc GIS 9.3 environment. In Next step, two variants of forest road were planned to connect the start point to the end point, using a 1) Shortest Path (SP) algorithm and 2) a skill expert. The results showed that the length and the cost of the variant planned by SP algorithm were 55% and 65% lower than the path planned by the expert before designing in the field, respectively. The results of the study after designing both planned variants in the field, demonstrated that the length and the cost of the SP-based feasible path were 19% and 21% lower than the expert-based variants, respectively. This means the SP saved 916000000 Rials. The results showed that using the zoning map cost in combination with a shortest path algorithm can lead to a more favorite layout of the forest roads than traditional methods of planning.