What does the "J" indicate in excavation illustrations?

In excavation illustrations, the "J" typically signifies an "Undercut," commonly referred to as an over beak. This notation is used to denote a specific type of contour in the excavation profile where the ground under the upper surface is cut back, creating a ledge or overhanging portion. Understanding how to identify an undercut is crucial in excavation and grading processes because it helps ensure proper drainage and stability of the surrounding soil. Recognizing and properly interpreting the "J" in technical drawings is essential for construction professionals as it impacts the design and safety of the excavation project.

Familiarizing oneself with these symbols enhances one’s capability to communicate effectively with other professionals and makes it easier to follow plans accurately.