What is the prepared base ready for the base course in road construction commonly referred to?

The term "sub grade" refers to the prepared base that lies beneath the base course in road construction. It is the layer of soil or rock that provides the fundamental support for the entire roadway structure. The sub grade must be adequately compacted and shaped to ensure stability and prevent future settlement that could compromise the road's integrity.

In road construction, the sub grade acts as the foundation for subsequent layers, including the base course and surface course. It is critical for this layer to be properly managed to achieve the desired performance and longevity of the road.

The other options represent different concepts or components in road construction. "Finish grade stakes" indicate the final elevation for the road surface but do not refer to the prepared base. "Surface course" refers to the top layer that is directly exposed to traffic, while "crown" refers to the slight elevation in the center of the road, designed to facilitate drainage. These components are essential but serve different functions within the broader context of road construction.