Railway Ballast Monitoring by GPR: A Test-Site Investigation

Abstract

Effective maintenance of railways requires a comprehensive assessment of the actual condition of the construction materials involved. In this regard, Ground-Penetrating Radar (GPR) stands as a viable alternative to the invasive and time-consuming traditional techniques for the inspection of these infrastructures. This work reports the experimental activities carried out on a test-site area within a railway depot in Rome, Italy. To this purpose, a 30 m-long railway section was divided into 10 sub-sections reproducing different various physical and structural conditions of the track-bed. In more detail, combinations of varying scenarios of fragmentation and fouling of the ballast were reproduced. The set-up was then investigated using different multi-frequency GPR horn antenna systems. The effects of the different physical conditions of ballast on the electromagnetic response of the material were analysed for each scenario using time- and frequency-domain signal processing techniques. Parallel to this, modelling was provided to estimate fouling content. Interpretation of results has proven the viability of the GPR method in detecting signs of decay at the network level, thereby proving this technique to be worthy of implementation in asset management systems.

A Review of GPR Application on Transport Infrastructures: Troubleshooting and Best Practices

“…• Ballast condition characterization, fouling and fragmentation (experimental test sections) [101,106]. • Fouled ballast assessment (laboratory tests) [101,[107][108][109][110].…”

“…• Ballast and subballast layer thickness: medium-frequency (from 400 MHz to 1 GHz) [90][91][92][94][95][96], most commonly used at network level. • Moisture and fouling detection: high-frequency antennas (from 1.2 GHz to 2 GHz) [90,93,101,103,104,106,280,281]. Not only are the antennas different, but the signal processing is also distinct, according to the purpose of the measurement.…”

“…These works have studied several aspects in order to enable better GPR results on railways from the type of antennas (high-frequency, ultra-wide band, etc.) [93,102,109,278] to antenna configuration during tests [106,279,280,284] and signal processing (scattering [267], time-frequency domain analysis [93,101,106,280,282,283], multi-channel analysis [285], and entropy-based analysis [107]).…”

PUMA Applied to Time Delay Estimation for Processing GPR Data over Debonded Pavement Structures

“…Ground-penetrating radar (GPR) is commonly used in civil engineering as a nondestructive testing (NDT) technique for the survey of various transport infrastructures [1], including pavements [2][3][4][5][6], tunnels [7][8][9][10][11], bridges [12][13][14][15][16], railways [17][18][19][20], as well as buildings [21][22][23][24] and retaining walls [25][26][27][28]. GPR relies on the propagation of electromagnetic (EM) waves and the backscattered echoes from any dielectric discontinuities to image the subsurface of the structure [29].…”

Quantification of the Mechanized Ballast Cleaning Process Efficiency Using GPR Technology

“…Ground Penetrating Radar (GPR), as another NDT technique, has steadily been in use in diagnostics of the railway infrastructure recently [7,8]. This method is still not the most routine tool implemented to evaluate the status of the railway infrastructure, however, it is being utilized to a greater extent due to its numerous benefits such as time efficiency, reduced costs, rapid fulfilling of surveys, continuous data acquisition of long sections, and the non-destructive principle [9].…”