What layer is placed immediately below the asphalt surface course?

The correct choice is the intermediate course, which is a crucial component of roadway construction. The asphalt surface course is designed to withstand traffic loads and provide a smooth driving surface. Beneath this surface, the intermediate course serves several important purposes.

Firstly, it helps in distributing the loads from the surface course to the layers below, thereby contributing to the overall structural integrity of the pavement. This layer can also provide some flexibility, which helps to accommodate slight movements and stresses that develop due to traffic and environmental factors.

In terms of layering sequence, the intermediate course typically lies directly beneath the asphalt surface course, while the base course, which is located below the intermediate course, is designed to provide stability and support. The subgrade lies underneath the entire pavement system and provides the foundational support, while the foundation layer is a broader term that can refer to various support layers. Thus, understanding this layering system is essential for ensuring the longevity and durability of roadways.