Volvo L-150D Wheel Loader was traveling south on surface that was not the road. Road was located to the east. The operator stopped & backed up per supervisor. Instead of continuing to back up & take the road, he then drove forward onto the working face of the ""pipline pit area"". Upon doing so, the loader tipped & fell approx 10-12'. He incurred cut to forehead & rec'd 13 stitches.