To model the truck-shovel dispatching problem and solve it in a mathematical way, an integer
programming model is presented for heterogeneous fleets which contain different types of trucks and
shovels in this section. Homogeneous fleets can be described by a simplified version of this model.
The model is built in such a way that the integer numbers of trips from a shovel to a dump site and
from a dump site to a shovel is determined for the considered shift duration so that the production target is
reached and truck operating cost is minimized. In such a way, a truck’s route for the complete shift is
determined explicitly. Approximation of the optimized result, as done by linear or nonlinear programming
approaches, is not required. The objective of the model presented is to minimize total truck operating
costs, which is related to the truck's traveling distance when both loaded and empty, and is calculated by