How is "pavement" defined in the context of a pavement structure?

In the context of a pavement structure, "pavement" is defined as one or more layers at the top of the structure. This definition emphasizes that pavement consists of various materials and layers designed to provide a surface suitable for vehicular traffic. The primary function of these layers is to distribute loads from traffic to the underlying soil, contributing to the durability and functionality of the roadway.

The pavement typically includes both wearing surfaces, which are exposed directly to traffic and weather conditions, and sub-layers that work together to support these surfaces. Hence, the term encompasses the entire system that forms the uppermost part of the road structure, making it essential for both safety and longevity.

The other options do not capture the comprehensive role and arrangement that pavement plays within the overall structure. For example, while the lowest layer providing support is a crucial aspect of pavement systems, it does not fully encompass the multi-layered nature of pavement as a whole. A synthetic layer added for durability refers to a specific enhancement but does not represent pavement in its entirety, and temporary materials used during construction do not define the intended final structure of the road.