High-speed rail lines, at ever increasing speeds and distances, are in development both in the UK and world-wide, but up-front capital expenditure can potentially be a major inhibiting factor both to the client and also in the eyes of the public. Cost reductions for these lines could be achievable if the initial costs of the physical construction, the duration of construction and the land take could be reduced. All three of these costs can potentially be reduced for embankments if the industry were to move towards a novel embankment replacement system. In addition embankment replacement systems could significantly improve the performance of the track structure as the dynamic properties of the contained material can be better controlled. However, such technology requires significant performance evaluation and the development of appropriate design guidance before UK industry can justifiably implement it in a project. This project therefore aims to evaluate and produce design guidance for two novel embankment replacement systems as a means to potentially reduce the cost of constructing new high-speed railway lines (particularly in urban environments) and improve the overall track behaviour and hence passenger experience.