control of a vehicle after leaving the traveled way. Regardless of the type of grading
used, projects should be examined in an effort to obtain flat slopes at low costs. For
example, fill slopes can be flattened with material that might otherwise be wasted, and
backslopes can be flattened to reduce borrow.
To better understand the various types of grading, it is necessary to become familiar
with the concept of a clear zone. Clear zone is defined as the unobstructed, relatively
flat area provided beyond the edge of the traveled way for the recovery of errant vehicles
and includes any shoulders or auxiliary lanes (Ref. 1, 2). Chapter 6 discusses the roadside
safety aspects of designing for the clear zone, including the use of barriers to
shield objects in the clear zone. In the following paragraphs, four types of roadside
grading are described. The designer must select the appropriate one for the roadway
being designed.