The selection of equipment for haulage in underground mines is a challenge due to its impact on both production rates and costs. The selected equipment should create an optimal match for the complete system and the point when equipment is to be added or replaced needs to be identified before the change is made. The use of discrete event simulation to compare two different haulage units of different size with the aim of improving production is presented. The feasibility of the production targets was also analysed. The result shows that, the smaller unit improves the average production from 52% to 75% while the bigger unit improves to 83% of the planned production target. This shows that the production will rise by 8% when smaller units are replaced by bigger units. This may need to be justified financially as the costs associated with changing the truck size might be recuperated by extra production gained. Furthermore, the study showed that current production targets were not feasible under the given circumstances.EU within 7th framework programme