Complex sentence: In civil engineering, the grader's purpose is to "finish grade" (to refine or set precisely) the "rough grading" performed by heavy equipment or engineering vehicles such as scrapers and bulldozers.
Split into simpler sentences: In civil engineering, the grader's purpose is to "finish grade" (to refine or set precisely). The "rough grading" is performed by heavy equipment or engineering vehicles such as scrapers and bulldozers.