Practical Applications of GPR Surveys for Trackbed Characterisation in the UK, Ireland, USA and Australia

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 was commissioned by Network Rail in the UK to implement ZARR on a total of 3 inspection trains which between them routinely collect around 20,000km of data per year. Network Rail have reported significant improvements to their track renewals process with a reduction in unnecessary ballast replacement, the application of more appropriate remedial actions and fewer pre-mature failures. Zetica Rail completed a survey for Irish Rail on the main Dublin to Cork line using their track geometry recording vehicle as the survey platform. The object of this 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. Over 5,000km of rail radar data has been collected and processed to characterize ballast quality for class 1 railroad companies in the USA. The works are designed to optimize maintenance planning by targeting the most contaminated ballast. ARTC recently commissioned Railtrak Systems working in partnership with Zetica Rail, to collect and process over 1,100km of rail radar data to characterize ballast quality and map subgrade irregularities and formation failure. The data collection vehicle was the AK inspection car and the works were designed to optimize maintenance planning by targeting the most contaminated ballast. The paper will describe how ZARR is being utilised to achieve impressive cost savings through: - Accurate prioritisation of problem trackbed, - Reduction in the number of trial holes required to investigate sites, - Effective integration of rail radar and track geometry metrics, - Accurate delineation of the extent of remedial works required, - Improved quality control measures, and - A reduction in the number of interventions during the planned life of the ballast.