What is the layer of compacted soil located between the surface course and the sub-grade called?

The layer of compacted soil situated between the surface course and the sub-grade is referred to as the base course. This layer plays a critical role in providing structural support to the surface course, which is the top layer that is subject to traffic loads, and helping to distribute those loads more evenly to the underlying sub-grade. The base course typically consists of aggregate material and is designed to enhance drainage and stability. By ensuring proper compaction and material quality, the base course helps to prevent deformation and extend the lifespan of the pavement or surface course above it.

Understanding the role of the base course is essential in earthworks and surveying, particularly in the context of pavement design and road construction. The other terms provided, such as finish grade stakes, existing grade stakes, and slope stakes, refer to different aspects of site preparation, such as marking the final elevations or indicating slopes, rather than the material layers within the pavement structure itself. Recognizing these distinctions helps in comprehending the overall design and execution of earthwork projects.