The truck dispatching problem in open-pit mines is formulated into an integer programming problem in order to
optimally determine the trip numbers of trucks from a shovel (dump site) to a dump site (shovel). The dispatching
result aims to answer the question of where should a truck go so that the production target is achieved with minimum
operating cost. An analytic method to determine the optimal fleet size taking advantage of the dispatching result is
also presented. It is shown by experiments that the proposed integer programming approach is capable of saving
15.65% truck operating cost than fixed truck assignment policy in the studied homogeneous fleet case. It is also
shown that the truck operating cost can be further reduced by proper use of a heterogeneous fleet.