Hand Signals, Voice Signals, and Communication
Signals are a control system
The operator acts only on signals from the designated signalperson - but anyone may give a STOP signal, and the operator must stop when a signal is unclear, when two signals conflict, or when a hazard appears. OSHA 1926.1417 and ASME B30.5 define the standard hand signals: hoist, lower, raise boom, lower boom, extend boom, retract boom, swing, travel, stop, emergency stop, and dog everything (hold). Learn them as a matched set; questions routinely mix up "raise boom" with "hoist" and "lower boom" with "lower load."
Communication planning
Before the lift, agree on the signal method, the radio channel, and who is in charge. Hand signals require an unobstructed line of sight; if it is lost, use radio, a relay signalperson, or a clear audible system. Radio: dedicated channel, tested before the lift, charged batteries, and a headset so the signalperson's hands stay free. Voice signals must be distinctive and understood by the whole crew; horns and backup alarms must be distinguishable from site noise.
Qualification
Signalpersons must be qualified by the employer, through recognized certification or a documented skills evaluation, and riggers who attach loads must be qualified as well. A qualified signalperson knows the machine's limitations well enough to refuse a bad signal.
Traps
- Treating "stop" and "emergency stop" as interchangeable.
- The signalperson stepping out of sight while the operator continues on assumption.
- Two signalpersons directing one crane at the same time.
- Assuming a radio removes the need to know hand signals.
Rule of thumb
One crane, one signalperson, one channel - and stop is always available to anyone on the crew.