An Inspection of Railway Ballast Quality Using Ground Penetrating Radar in Finland

Abstract

The maintenance of heavy haul railway lines causes considerable cost and in many cases difficulties to rail traffic. Railway infrastructure management in Finland is important because in many locations the same railway lines are used by both freight and passenger trains. Along with the mixed traffic, the cold climate presents challenges in keeping the track in good condition. There is a great demand for economical and non-destructive methods that provide continuous condition information of track structure. In recent years, the ground penetrating radar (GPR) technology for structure inspection has improved to faster systems and better data quality.This article presents the main results from a research programme that was aimed to identify different GPR-based railway ballast degradation classes and to develop a preventative maintenance planning system. An extensive reference sampling and laboratory analysis has been performed to aid in developing the GPR-based classification method for qualifying the ballast fouling. Classification is made by a fouling index, which is calculated from the frequency contents of the GPR signal. This quality classification can be utilized in the planning of undercutting programmes.

Analysis of the Dynamic Wheel Loads in Railway Transition Zones Considering the Moisture Condition of the Ballast and Subballast

“…The reflected energy, originating from the interfaces between materials of different dielectric properties, is received and recorded for analysis. GPR data consists of changes in reflection amplitude, changes in the arrival time of specific reflections, and signal attenuation [32,38]. The method provides a continuous profile of the thickness and properties of railway structures, which can be used to analyse the quality of track substructures, such as the moisture susceptibility of ballast and subballast, fouling of ballast, layer deformation, and mud pumping [39][40][41].…”

“…The processing, visualization, interpretation, and analysis of the GPR data are performed using the Rail Doctor software (version 3.2), developed by Roadscanners Oy, Rovaniemi, Finland, 2017. The measurement system has been calibrated against sample analysis [38] and pit tests [39]. A screenshot from the recorded video is shown in Figure 4a, wherein a transition zone consisting of embankment and a bridge can be found.…”

GPR Laboratory Tests For Railways Materials Dielectric Properties Assessment

“…In some countries, GPR tests have been performed along tracks with the aim of detecting zones with problems in both ballast and subsoil layers. First results have shown that GPR is a reliable technique to assess track geometry problems and consequently to improve maintenance planning [11][12][13][14][15][16].…”

Evaluation of the GPR frequency spectra in asphalt pavement assessment

“…However, GPR data provide further information that could be used in order to deter- 34 mine the inner conditions and characteristics about materials. In this paper, the possible analysis of the 35 frequency spectrum of GPR signals is analysed and discussed. Several tests were carried out in a portion 36 of a highway in two different stages of its service life.…”

“…The method is based on determining the stiffness modulus of 49 each layer that makes up the pavement using back-calculation in 50 order to obtain the state of stress and strain in significant points [3]. and locating cavities beneath the structure of a road (e.g., [5][6][7][8] to concrete [32,33], to ballast for railway infrastructure [34,35] 168 and to other media [36]. 169 Other studies have analysed the alterations in the frequency 170 spectra as the ratio of two materials changes.…”