This paper discusses the geodynamic challenges in high speed and high axle load railway projects, especially for soft ground conditions. Three main issues need to be solved by the engineering community: critical speed and excessive dynamic response or the track structure and supporting ground, accelerated degradation of the track structure, and vibration in track-side dwellings and buildings that can inconvenience people and disturb sensitive equipment. The paper describes the nature of these three issuers and discusses the prediction tools and design strategies. The importance of knowledge on the ground characteristics, especially the dynamic properties, is emphasized. Countermeasures are discussed. Further needs are pointed out, including the most urgent needs for further research and development. The benefit of standardization solutions, international collaboration projects and the sharing of knowledge is highlighted.