Which term refers to the width of the surface course including both shoulders?

The correct term referring to the width of the surface course, including both shoulders, is "roadbed." The roadbed encompasses not only the primary surface area where vehicles travel but also incorporates the additional space allocated for shoulders on either side. This is crucial in roadway design and construction because the roadbed must support the weight of vehicles as well as provide safety measures, such as the shoulders, which allow for emergency stops and help manage water runoff.

Understanding this term is essential in earthworks and surveying, as it relates to how a roadway is structured to ensure durability, safety, and proper drainage. The roadbed's dimensions can significantly impact traffic flow, design costs, and maintenance needs.