Describe the process of subgrade preparation.

Subgrade preparation is a crucial step in road construction that focuses on ensuring a stable foundation for the layers above it, typically asphalt or concrete. The process involves grading the existing soil to achieve the desired surface elevation and slope. This grading is essential for proper drainage and maintaining the integrity of the road structure.

Once grading is complete, the next phase is compacting the soil. Compaction increases the density of the soil, which minimizes settling and shifting once the pavement is laid. A well-compacted subgrade helps to distribute loads effectively, reducing the risk of pavement failure due to excessive stress or poor support.

By ensuring that the subgrade is both graded and compacted adequately, engineers can guarantee that the pavement above will perform well over time, resisting deformation or cracking under traffic loads. This makes the correct choice an accurate representation of the necessary actions that contribute to a resilient and long-lasting roadway structure.