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Sandberg GPR Surveys

GPR surveys to find out what's below the surface.

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Railway ballast thickness and evaluation surveys

Railway tracks with ballast

Our GPR survey can provide objective and measurable information about railway ballast thickness, condition and anomalies; – critical factors for an effective maintenance policy.

The properties and thickness of the ballast layer comprising the rail-track structural support largely determine the quality of the substructure and its ability to withstand the various loading intensities imposed by rail traffic. Minimising track deflections and long term track settlements are desired goals for track design and performance. It is known that the proper operation of railway ballast can be compromised by the presence of fine-grained material which can progressively fill the voids in the ballast and affect performance.

Ground Penetrating Radar (GPR) can evaluate railway ballast condition rapidly and non-destructively and enables the measurement of ballast thickness and the detection of changes in material properties. The fines within the ballast retain more moisture, increasing the permittivity of fouled ballast, therefore areas of fouled ballast can be identified.

Survey method

For railway ballast surveys, we typically use a GSSI GPR control unit with a digital dual-frequency antenna with central frequencies of 300 MHz and 800 MHz. GPR scans can be conducted using antennas with different central frequencies. A higher frequency antenna provides better resolution and more detail, however, the penetration depth is limited. By using a dual-frequency system, the best of both is achieved; the 800Mhz provides high-resolution data to approximately 0.9 m depth, while 300Mhz provides greater depth penetration. The penetration depth depends on site conditions, but under favourable conditions, penetration depths of up to 3 m can be achieved.

For comparison, GPR scan lines can be collected in the 6-foot, 4-foot and cess.

Survey results

Cross-section plots are produced, typically with 0.1 m horizontal sampling density and 0.01 m vertical resolution showing variation in ballast thickness. Areas of fouled ballast or ballast deterioration are also identified.

Railway ballast thickness plot
Railway ballast thickness plot as detected by GPR

Wondering what else GPR can be used for? GPR surveys to find out what’s below the surface – find out more about our most popular GPR surveys.

Need more information?

Contact us to find out more about GPR railway ballast thickness and evaluation surveys and how we can help you:

Telephone: 0207 565 7056
Email: gpr@sandberg.co.uk

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Sandberg GPR

We undertake GPR site surveys with data interpretation and reporting across the UK and abroad. Do not hesitate to contact us with your requirements.

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5 Carpenters Place,
Clapham, London,
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Company No. OC304229

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