How is a hand signal defined in roadway worker protection?

A hand signal in roadway worker protection is defined as a signal given by the motion of a person's hand and arm. This definition is crucial because hand signals are a primary means of communication in situations where verbal communication may be difficult or impossible due to noise, distance, or the presence of equipment. In the context of roadway work, these signals are vital for ensuring safety and coordinating actions among workers and operators.

Using hand signals allows workers to convey clear and immediate instructions, such as directing machinery, signaling to stop or proceed, and facilitating safe movement around work zones. The visibility and clarity of hand signals are significant because they can be seen from a distance and are universally understood within the context of roadway work.

The other options present misunderstandings of what constitutes a hand signal. Radio communication does not fall under the definition of a hand signal, as it involves verbal communication through devices rather than physical gestures. A signal below the knee is too specific and does not encompass the full range of hand signals used at various heights and angles. Lastly, a coded signal used only in emergencies is also incorrect, as hand signals are commonly used in routine operations, not just in emergencies, to ensure ongoing communication in a safe working environment.