With the constantly increasing demand for heavy freight transportation, railways have become an extremely important element in the economic wellbeing of any country, and particularly in a developing country like South Africa. It is thus the duty of track engineers to maintain a continued understanding of the rail track infrastructure. Track designs should be as cost-effective as possible and should be sensitive to the costs associated with the planning, development and maintenance of the track structure. Extensive and continuous research is therefore required to determine the influencing parameters and to maximise the track performance and the lifetime of the track structure.
Deformation of the track structure is a good measure of the structural capability of a track structure or of the expected track performance. This deformation is vastly dependent on the support of the track structure. The ballast support and the foundation of the track structure are therefore key components. Poor support will lead to large deformations, which in turn will accelerate track deterioration. This will increase the maintenance need and therefore the total cost of operating the asset within an acceptable functional condition.