International rail freight transport plays an essential role in reducing carbon footprint, with Eurasian rail transport as a successful example. However, multiple interfaces across totally different rail systems increase the complexity of information exchange. The quality of information directly influences the quality of planning. The impact of information exchange and its integration into international rail freight transport planning activities has not yet been studied extensively. This paper presents an integrated tactical rail planning method (ITPM) for international rail freight transport focusing on information integration. Advanced mathematical models for Decision Support Systems (DSS) based on information integration are also suggested.