Tolerance zone

Definition

The two-foot corridor either side of a utility marking where no machine may dig.

Why It Matters

It is two feet on each side of the field marking, and inside it the crew finds the line by hand before any powered equipment moves. Every buried installation is presumed live. A vacuum device is allowed only where the excavator declared it on the ticket and the operator agreed, and disagreement is recorded on the response. The strike history is the cheapest read there is on whether a crew actually works inside this rule, and the liability follows the business and not the operator who was holding the controls.