Road investment scenarios in Northern Sweden

In this paper we describe a mixed-integer linear programming model for a road investment problem. We only focus on the upgrading of gravel roads, hence maintenance and new roads are not included in the model. Furthermore, we use the model to calculate the optimal level of upgrading over a 10-year planning period, at a forest area owned by a Swedish forest company. We test six different scenarios: that is, three different scenarios on the length of the thawing period in spring for two different objective functions. We conclude that the type of objective function to be used depends on the situation and that the entire network of roads must be optimized simultaneously, to avoid sub-optimizations. Although the forest area includes 440 roads, it is possible to obtain the global optimal solutions from the optimization within a few minutes using commercial software. This is a promising prospect, since the aim is to use the model as part of a future decision support system for strategic planning of road investments.