Railways are facing the challenge to simultaneously increase the capacity and the operational performance of their network. Automatic train operation (ATO) can be one of the technologies to increase the capacity of the railway network. The specifications for ATO over the European Train Control System (ETCS) automatic train protection system have been defined. However, testing is taking place over legacy automatic train protection systems , such as ATBNG, as well. ATO requires information from the automatic train protection system. The goal of this master thesis is to determine the data gap between ETCS and ATBNG in relation to ATO. First a generic ATO model is developed from literature. This model presents the information required and produced by ATO. The model is used as a framework for the analysis of ATO over ETCS and ATO over ATBNG. This analysis resulted in a conceptual model of both ATO over ETCS and ATO over ATBNG. The conceptual model shows that ATBNG can provide the required information if the ATBNG operational envelope is used as the relevant safety envelope. However, currently the operational envelope of the NS’54 signalling system is the relevant safety envelope. Additional information is required to allow ATO to determine the NS’54 operational envelope. Furthermore, ATBNG is not capable of presenting ATO information to the train driver. A new ATO DMI is required. Moreover, the ProRail traffic management system is not yet capable of providing ATO with the required information for both ATO over ETCS and ATO over ATBNG. To validate the conceptual ATO over ATBNG model three case studies have been worked out. The study performed for this master thesis is an exploratory study, therefore validation of the findings and assumptions is required.