Researchers developed a second-generation RAdar Ballast Inspection Tool (RABIT) using ground-penetrating radar (GPR) for use by track inspectors. This system is much lighter (26 lbs/11.8 kg) than its predecessor (63 lb/29 kg) and is truly portable. It has a single bi-static antenna pair that straddles the tie so the ballast properties under the tie can be measured. During a measurement, the RABIT rolls down the track and obtains average ballast properties over a span of 10 cribs, thereby reducing problems associated with local variability in ballast properties and tie geometry. Researchers constructed a test track with known ballast properties and known fouling and moisture properties ranging from 0-30 percent and 0-4.5 percent by weight, respectively. A neural network was trained to map GPR waveforms to ballast fouling and moisture. The correlation factor between the RABIT estimates and measured values determined from physical ballast samples was better than 0.9. Researchers are planning further testing on in-service track to further validate the approach