grade elevation(The earth is hardly flat, and surveyors in construction overcome this in building projects by flattening the ground into a specific level, or grade, using tools such as a grade rod. Used with a level and grade stakes, a grade rod measures the difference between the elevation of the ground and the prescribed grade elevations. Though grade rods are of many types and levels of sophistication, all determine whether land needs to be filled or cut. Reading a grade rod reveals the difference between the existing grade and the prescribed grade elevation. Alexander Demidov)
