Designing a Forest Road Network Using Mixed Integer Programming

Nacrtak Forest roads are an essential yet costly part of forest management, and optimization methods are important tools for planning road systems to support harvesting. This paper presents a Mixed Integer Programming (MIP) optimization model to design a forest access system consisting of logging roads for trucking and access spurs for skidding. The network designed is hierarchical in the sense that the two transport systems require significantly different road standards, and timber may only be transferred from access spurs to forest roads. All timber must be transported from harvest sites to exit nodes that connect the forest road network to public roads. A dense network of potential connections is formed by overlaying a regular grid onto the forest, and then calculating costs of inter-node connections using GIS topographical data. Feasible arcs thus determined are input to the optimization model. The model minimizes total cost of road construction and maintenance, skidding and whole transportation in forest. It can be used to develop road system alternatives to support the process of planning the total access system. The model performance is explored on a study area in a mountainous region, where a persistent access network for partial harvesting is required. High quality solutions were achieved in reasonable computational time.