Design life prediction of a heavy haul track foundation

Transnet Freight Rail monitors the behaviour of a new track foundation, constructed in 2004, on the South African Coal Line. This site forms part of a major rehabilitation project, aimed at increasing the capacity of the line to sustain future growth in annual tonnage. Sophisticated instrumentation is used to measure resilient and permanent deformation of the track foundation. Preliminary results of this research were published shortly after the construction of the new track foundation. Results of the permanent deformation, gathered over a period of 5 years, are now presented to provide new insight into the long-term behaviour of track foundations. Permanent deformation measurements are used to calculate the expected design life of a track foundation. The results are used to predict permanent deformation and ultimately the design life of the track foundation under heavy haul loading conditions. The research provides a scientific basis for planning foundation rehabilitation in the light of sustained capital expansion and projected tonnage increase on the Coal Line and other heavy haul lines.