The effect of the density of candidate roads on solutions in tactical forest planning

In this paper, we inquire into whether, and by how much, the use in tactical planning of a dense set versus a sparse set of candidate roads can reduce the two major costs (construction and transportation) of forest operations. This inquiry is conducted by using an optimal road location model to generate dense and sparse sets of candidate roads for three different problem instances. These problem instances were then solved using a mixed integer representation of the integrated tactical planning problem. The results show that the use of a dense set versus a sparse set of candidate roads, for all three problem instances, yielded solutions with a mean decrease in transportation and construction costs of 34.34% and 6.94%, respectively. The mean increase in revenue was 1.06%, and the mean increase in the objective function value (revenue minus the total road construction and transportation costs) was 5.62%. In addition, the mapped solutions reveal the spatial attributes of a lower versus a higher cost road network: straighter roads and more efficiently located forks within the road network. These results were obtained to illustrate how reductions in the costs of transportation and road construction can be achieved in tactical planning.