What is the term for the preparation of the subsoil grade for top surfacing of roads or lawns?

The correct term for the preparation of the subsoil grade for the top surfacing of roads or lawns is grading. Grading involves shaping the land in a way that establishes the desired contours and levels of the surface necessary for drainage and support of the final surface layer, be it asphalt, concrete, or sod. This process is crucial as it influences the site's drainage patterns, structural stability, and aesthetic appearance.

Choosing "grade" does not fully encompass this process, as "grade" refers more to the angle or level of a slope rather than the comprehensive preparation work involved in grading. "Gradient," while related, specifically describes the steepness or incline of a slope, which does not reflect the entire scope of preparing the subsoil. "Site preparation" is a broader term that might include grading along with other activities like clearing and excavation but does not specifically emphasize the shaping of the subsoil for surfacing. Thus, grading is the most precise term in this context.