Roadway pavement is made up of multiple layers of materials to form a durable structure that can support vehicle traffic.

Pavement Detail illustration

Illustration: Pavement Detail cross section.

 

Pavement Detail photo

Illustration: Pavement Detail exploded view.

Source: The image above illustrates the key components of Pavement Detail.

A. The surface course, also referred to as the wearing course, is the upper layer in a roadway and is composed of asphalt concrete.

B. The binder course is a layer of asphalt concrete that holds the materials above and below it together.

C. Base course provides additional support, allows for drainage and provides resistance to freezing.

D. Subbase course is often made from crushed stone or other filling.

E. Compacted subgrade is compacted soil or dirt, and provides the foundation of the pavement structure. It can become harder and more stable over time.