Barricade means an obstruction to deter the passage of persons or vehicles.
Signs are the warnings of hazard, temporarily or permanently affixed or placed, at locations where hazards exist.
Signals are moving signs, provided by workers, such as flaggers, or by devices, such as flashing lights, to warn of possible or existing hazards.
Tags are temporary signs, usually attached to a piece of equipment or part of a structure, to warn of existing or immediate hazards.
[67 FR 57736, Sept. 12, 2002]