The new generation of GT6600 hi-rail ultrasonic rail flaw detection vehicle is based on our hi-rail vehicle platform. The vehicle can test at speed up to 40km/h. When off track, the hi-rail gears can be retracted and thus the vehicle can be driven on the road. The test carriage is hydraulic controlled and can be remotely operated. The hi-rail ultrasonic rail flaw detection vehicle is suitable for long distance testing under the very worse environment. It has the characteristics of high speed testing while maintaining high detection rate with easy operation. It features two-wheel probes on each rail for total 18 channels. It can detect transvers defect at the rail head, bolt hole break and transvers defect at the base.