Purpose-built technology for seeing inside the track bed
The survey platform
KHEERAN surveys run from hi-rail vehicles fitted with a multi-channel GPR array covering the track centre and both ballast shoulders in a single pass — the three-line configuration used in Federal Railroad Administration evaluations, capturing the asymmetric fouling patterns real tracks develop. Air-coupled horn antennas are suspended above the ballast surface, so nothing touches the track and surveys proceed at normal hi-rail speeds with minimal traffic disruption.
Multi-frequency radar: the right antenna for each question
2 GHz high-resolution antennas. The workhorse for fouling assessment. The air voids in clean ballast scatter 2 GHz energy strongly; fouled ballast does not. Penetration to roughly 75 cm covers the zone where undercutting and cleaning decisions are made, and the scattering method is largely insensitive to moisture — so results hold across weather conditions.
400 MHz deep-profiling antennas. Penetration to 1–2 m for full substructure layering: ballast, subballast, subgrade interfaces, ballast pockets and formation problems. Also supports frequency-spectrum fouling analysis, the second method validated in FRA testing.
Combined deployment. Running both frequencies in one survey delivers fouling detail and deep structure simultaneously — and lets two independent methods cross-check each other.
Positioning and context data
Radar data is only useful if you know exactly where it came from. Every KHEERAN survey records GPS positioning synchronized with the radar stream and tied to your chainage or milepost system, distance encoding from calibrated wheel encoders for precise linear referencing, and video asset mapping so every radar feature can be matched to visible track context — crossings, turnouts, mud spots, drainage structures.
Data processing pipeline
Raw GPR generates enormous data volumes — a single survey day can produce more data than any team could interpret manually scan by scan. Our processing chain condenses raw radargrams into scattering-amplitude and frequency-spectrum profiles at better than 100:1 compression while preserving the condition information that matters. The output: continuous fouling categories, layer depths and moisture indicators by chainage — not wallpaper-sized radargrams for your team to decipher.
Calibration equipment
Quantitative results require ground truth. We take targeted column samples at radar inspection depth, with sieve analysis tying radar classifications to the Selig Fouling Index, AREMA gradation envelopes or your network’s own thresholds.
Turnaround
First-pass results within 24 hours of survey completion — a capability benchmark established in FRA system evaluations — with the fully calibrated report following ground-truth analysis.