Railroad ballast is uniformly graded coarse aggregate between and immediately underneath the railroad ties. The purpose of ballast is to provide structural support for the heavy loading applied by trains. Over time, ballast is progressively fouled by finegrained material that fills the void space. Hence, the structural integrity of seriously fouled ballast can be compromised, leading to track instability and ultimately, train derailments. As a preventive measure, it is very important to be able to detect fouled ballast as soon as possible. Ground penetrating radar (GPR) has been tested over the past 25 years to evaluate ballast integrity. The traditional approach to interpreting GPR data obtained on railroads has been the mapping of reflecting horizons, which may or may not be observable in the GPR data. Advancements in the development of GPR hardware have led to higher-frequency GPR antennas, including a 2 GHz antenna. Data have been obtained with 2 GHz horn antennas along 2 miles of test track at the Transportation Technology Center Inc. in Pueblo, Colorado. A series of 15 ground truth cross-trenches were dug. Visual identification of layer interfaces was made, and samples were collected for moisture and sieve analyses. Comparison of the processed GPR data and the ground truth information reveals a correlation between the strength of the scattering from ballast aggregate and the degree of ballast fouling and moisture content. The analysis incorporates specific data processing. Results suggest that routine inspection of railroads is feasible. The technique is especially suited to assess the ballast fouling condition near the bottom of railroad ties.
Advances in railroad ballast evaluation using 2 GHz horn antennas
Fortschritte bei der Untersuchung von Schienen-Schotter mittels 2 GHz Hornantennen
2006
10 Seiten, 15 Bilder, 4 Quellen
Conference paper
Storage medium
English
Railroad Ballast Evaluation Using Ground-Penetrating Radar
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