Optimum ramp design in open pit mines

The problem studied in this paper is that of designing the optimal open pit haulage ramp that, for a given ramp width and a maximum ramp gradient, connects two points of the mine, minimising construction and operational costs. Because in-pit ramps require the removal of a considerable amount of non-valuable material (stripping), we discuss two different problems: high stripping (or in-pit) ramp design and low stripping (or ex-pit) road design. For the first situation, we present an integer programming model; in the second case, a shortest path approach is undertaken. In both cases, the models can be solved exactly, and include gradient and curvature constraints. The proposed formulations have been tested on real mine data, showing a significant reduction in cost compared to the previous mine design.