Automated excavating uses automated dozers and other earthmoving equipment to move material at a worksite. When such equipment is required to avoid a temporary obstruction, traverse between work slots, or traverse between work areas, a controller uses information from real-time sensors and contour maps to determine a new route to the destination. The controller also determines in real time whether the proposed route will keep the equipment on terrain with slopes that do not exceed a slope limit set for the mobile excavation machine. If not, the controller re-routes the machine to a new path over terrain with acceptable slopes.