Optimal forest transportation with respect to road investments

This paper concerns roundwood transport on gravel roads. The forest sector in Sweden has identified the road quality as a major problem, in particular in the spring, when the ground is thawing. The model simultaneously optimizes roundwood transport and road investments on gravel roads. The model is a mixed-integer programming model, since the road accessibility variables need to be binary. Investments in surface roads, maintenance and construction of new roads are not included in the model. We test the model with a sample problem using a small area. With a simple heuristic method 'near to optimal' solutions are obtained in reasonable time. In the last section we make some concluding remarks and discuss future use of the model. Heuristics and aggregation are two different ways to solve the problem in reasonable time.