Characteristic It adopts CAN bus communication, digital intelligent control with strong antijamming capability. Each ultrasonic side skid shoe has a special ultrasonic probe to be the temperature compensation that makes higher measurement accuracy. LCD displays Chinese operation interface. The operation is easy and simple. It has of reminding of operational data, working condition, stoppage testing automatically, high level intelligently. The totally closed structure of controller and ultrasonic side skid shoe is waterproof, shockproof and pollution resisted. It has the non-contact, non- mechanical wear design without adhesion and wash. The inlay installing can be moved freely. The balance beam is collapsible with compact structure and light appearance. It can change the places randomly without disassembly. It can vary freely with going forward and drawing back. It can be used for ramp, changed slope, interchanged and other special road surfaces. It deals with the starting, ending, juncture, manhole cover and some other special working condition freely.