The conceptual design of automated freight transport systems is a challenging matter. It involves many different parties, types of people and disciplines which all have to work together to develop a system which is often new and complex. Automated freight transport systems typically have a long lifecycle, require large investments and can have a great impact on their environment. The conceptual design phase is one of the first and one of the most important phases in the development of such a system, as the decisions made here will influence all subsequent phases of the systems lifecycle. Although people have been designing for many years, and many design methods and techniques have been developed, there was no design approach for the conceptual design of automated freight transport systems. The lack of such a design approach became apparent during the design of a new automated underground freight transport system in the Netherlands (the so called OLS). This observation formed the main motivation for writing this thesis. The goal was to develop an approach for the conceptual design of automated freight transport systems and to use this approach in the OLS project. The design approach itself has been fully developed and is extensively discussed in this thesis. The characteristics of automated freight transport systems, discussed in Chapter 2, helped to guide the literature survey on design methodology, presented in Chapter 3. Criteria were formulated to evaluate both, the existing models found in literature as well as the new developed design approach for the conceptual design of automated freight transport systems. It was concluded that, although the existing models present a number of interesting and useful items for the conceptual design of automated freight transport systems, not one satisfied all criteria. The new developed design approach, presented in Chapter 4, did satisfy all criteria. As such it was concluded that the design approach distinguished itself from all other models found in literature, and could be regarded as new and unique. Furthermore the new design approach was considered to be well-founded, as it was based on an extensive literature survey on design methodology and further analysis of the most important well-established models. The development and foundation of the design approach proved more complex and time-consuming than initially expected. Therefore, the design approach could not be fully applied within the OLS project. As such, the initial goal of this thesis has been achieved only partly. Nevertheless, the conceptual designing of OLS terminals has been presented in Chapter 5 as a case study. For this case study, the design activities as they took place during the OLS project were mirrored to the new developed design approach. All the elements of the new design approach have been discussed. The case shows how a large complex project can be structured using the phases defined in the design approach. Furthermore, the design activities as they were performed within the OLS project could be clearly positioned under one of the five design steps of the conceptual design process defined in the new design approach. Several of the Multi-X aspects, such as multiple layers, multiple disciplines and multiple stakeholders could also be clearly recognized within the OLS project. It was concluded that, although not all elements of the new design approach were considered in the same extensive or desired manner within the OLS project, the case study does demonstrate how the new design approach could work in practice. Furthermore, it was found that using the design approach would not only make the design process more transparent, and the product reproducible and justifiable, but would also make it easier to cope with changes and develop new concepts within a relatively short period of time. Apart from being an example on how the new design approach can work in practice, the OLS case also presents some lessons learnt. These and other findings discussed throughout this thesis are also presented in the summary and conclusions at the end of Chapters 2, 3, 4 and 5, and in Chapter 6 (Conclusions). Although this thesis focuses on the conceptual design of automated freight transport systems, it is felt that the newly developed design approach could also be used for several other types of complex systems