Which communication method frees both hands but cannot be used when more than one crane is on site?

Which communication method frees both hands but cannot be used when more than one crane is on site?

• A. Whistle signals
• B. Radios
• C. Sign language
• D. Verbal commands

Answer: (A)

Whistle signals are designed so the signaler does nothave to use their hands to convey instructions—blowing a whistle lets you keep both hands free to observe the lift and operate controls if needed. The trade-off is that, on a site with more than one crane, a single whistle blast is heard by everyone, so it can’t reliably direct a specific crane. That ambiguity makes whistle signals impractical for coordinating multiple cranes, even though they free the signaler’s hands. In contrast, other methods either require hands-on devices or rely on direction to a particular operator, which is harder to manage with multiple cranes.

Whistle signals are designed so the signaler does nothave to use their hands to convey instructions—blowing a whistle lets you keep both hands free to observe the lift and operate controls if needed. The trade-off is that, on a site with more than one crane, a single whistle blast is heard by everyone, so it can’t reliably direct a specific crane. That ambiguity makes whistle signals impractical for coordinating multiple cranes, even though they free the signaler’s hands. In contrast, other methods either require hands-on devices or rely on direction to a particular operator, which is harder to manage with multiple cranes.