In order to encourage a substantial shift from highly polluting freight transport by road to more sustainable Inland WaterWay (IWW) transport, one of the possible options is to optimize handling activities at Inland Waterway Terminals (IWTs). Therefore, this research focused on efficiencies of IWTs and possible improvements by analyzing the optimal configuration and operation of Reach Stackers (RSs) and terminal Yard Cranes (YCs) given certain throughput levels at IWTs. Our paper contributes to current scientific knowledge through the development of a tailor-made new model based on the maritime container terminal literature combined with the specificities of IWTs. The model results show that a growing throughput results in scale economies for IWTs. For small terminals, an unbalanced import/export-ratio (80-20 or vice versa) is often more efficient (and thus sustainable) than a balanced ratio (50-50), while this changes for larger terminals. Furthermore, by applying the model and analyzing the sensitivities, the paper contributes to managerial decisions to be taken by IWW terminal operators and also gives insight into the consequences of certain sustainability policies of local authorities on terminal operations. If these environmental rules and regulations are implemented, results indicate that this leads to a lower terminal capacity and thus higher costs.