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Case Studies>Irish Rail

Irish Rail

DEPTH OF BALLAST, FORMATION FAILURE AND SUBGRADE EROSION

Zetica’s Advanced Rail Radar (ZARR) system is deployed in many countries across the world. The system utilises ground penetrating radar (GPR) to continuously map changes in the thickness and quality of the ballast layer across a network.

Zetica Rail completed a survey for Irish Rail on the main Dublin to Cork line using an existing track geometry recording vehicle as the survey platform. The object of the survey was to map changes in the geometry of ballast layers as well as target areas of subgrade erosion, drainage problems and to detect buried structures. The results were combined with track geometry to provide a strategic tool for maintenance planning.

The example data panel above shows (top-bottom) – greyscale radargram, digitized layers in the center, digitized layers over the shoulders, colour strip charts showing thickness of ballast against defined thresholds, ballast layer roughness, a combined ballast thickness and layer roughness index, and a contoured map of depth to fouled ballast/formation. Zoomed view of radargram shows an example of sub-grade erosion.

The GPR reports and GPR-derived trackbed indices are currently being used as part of a major remediation and renewal programme over the full route. The information is an important tool which is being proactively used to allow focused planning of trackbed remediation works on those areas most in need of rehabilitation. This allows an optimisation of available budgets and is thus a cost-effective tool in the trackbed remediation programme.