Which item is included in roadway sampling categories?

• A. Pavement surface.
• B. Shoulder.
• C. Embankment.
• D. Sub grade.

Answer: (D)

The main idea here is that roadway sampling categories are organized by the layer of the road that is being tested and prepared as the foundation for the pavement. The subgrade is the layer of soil that sits directly under the pavement structure and carries the loads from traffic. Because it forms the base that determines how well the pavement will perform, it is the category that’s routinely sampled and tested for density, moisture content, and compaction to meet project specifications. In practice, you verify that the subgrade has been compacted to the required density and moisture conditions, since these factors directly affect stability and drainage.

Pavement surface refers to the finished wearing layer, which is tested as pavement materials rather than as part of earthwork sampling. A shoulder is a road feature and can involve fill, but it’s not the primary foundation category used in roadway earthwork sampling. Embankment is indeed fill material, but the context here emphasizes the foundational soil layer directly beneath the pavement, making subgrade the most relevant sampling category.