ABSTRACT
For designing new track structures and for reducing trackmaintenance costs, an understanding of the complex mechanisms of track deterioration is necessary. Most of the design methods prevalent in practice are based on conservative estimates of settlements and stress-transfer between the track layers. Due to complexities in the behavior of the composite track system consisting of rail, sleeper, ballast, sub-ballast and subgrade subjected to repeated rail traffic loading, the track design techniques are still far from advanced. In order to gain more insight into the stress-strain mechanism of the track substructure, a field trial was conducted on a section of instrumented railway track in the town of Bulli. The benefits of a geocomposite layer installed at the ballast-capping interface and the relative performances between moderately-graded recycled ballast and traditionally very uniform fresh ballast were also examined during this study. The design specifications for the instrumented track were provided by University of Wollongong and the field trial was sponsored by RailCorp, Sydney. The details of new equipment, field installation and monitoring procedures alongwith records of measurements are described in the following sections.
