Gotta go back out there with the box blade and give it another go. Need to try lifting the box on one side to scrape up the middle of the drive and deposit it on the edge.
I was also out at the asphalt road trying to take the accumulated lip of dirt off the edge so that water on the road runs off rather than running down and then cutting my driveway. I figured out that it was essential to get exactly square to the road, otherwise the bucket touches down on one corner and the rest is hanging in the air. I bet that narrow county road has lost 18-24" of width due to dirt encroaching from the sides. The rain runs out of the fields uphill of the road and brings silt onto the road and then deposits it on the edge as it runs off the other side.
Ian