Driving North on the I-35 access road north of Dallas I saw an Orange tractor (about the size of a Kubota 3710) leveling dirt on the George Bush Toll Road embankment. Driver turned down the hill with his box blade and really accelerated. At the bottom of the hill he turned sharply while at the same time hitting the hardpan where the hill leveled out with access road. First the right side rear tire which was now at the bottom of the hill bounced about 6" off the ground. Then the uphill side tire bounced about 8" off the ground. This of course launched the driver. He tried to hang on but couldn't. His attempt to hang with his right hand put him in a worse position than if he would have been thrown clear. He did a 180 degree turn in the air and ended up standing next to the tractor facing the right rear tire (as if you were about to climb on.) Tractor must have been hydrostat because it stopped immediately. I belive this is the only reason he wasn't crushed.