Repeatability and Reproducibility of GPR (Ground Penetrating Radar)

 GPR commissioning procedure for monitoring ballast bed health on Indian Railways.

**Testing Procedure**

- The objective is to evaluate the GPR system's repeatability and reproducibility in detecting ballast layer thickness, clean ballast depth, and ballast fouling index.

- Test site must be a 50 km track section, free from obstructions.

  

**Test Runs Overview**

- Repeatability testing involves two runs at speeds of 20 km/h, 50 km/h, and 100 km/h, totaling six runs.

- Reproducibility testing includes one additional run in the opposite direction with varying speeds based on site conditions.

**Data Processing & Evaluation**

- Consistency of measured data is verified using reference points and GPS.

- INTEGRAL software processes GPR data, excluding distorted areas.

**Parameter Evaluation**

- Ballast Layer Thickness: Calculated using dielectric constant of 5, with repeatability and reproducibility metrics defined.

- Clean Ballast Depth: Classifies depth into seven categories, with matching results calculated for repeatability.

- Ballast Fouling Index: Assigns fouling levels from 1 to 5, with matching results calculated for repeatability.

**Acceptance Criteria**

- GPR system commissioning is declared when repeatability is ≥ 85% and reproducibility is ≥ 80% for all parameters.