Relay Signal Through a Blind Corner
You are the qualified signal person for a 90-ton truck crane setting a 10-foot concrete panel into an interior courtyard. The crane is on the street; the operator can see the courtyard gate but not the landing zone. You stand at the landing zone and can see the load, but the building corner blocks your view of the operator. A laborer at the corner can see both you and the operator and offers to relay your hand signals. He has worked around cranes but has no signal-person qualification. The operator's radio is on a channel shared with a concrete pump crew, and reception is intermittent. Wind is 8 mph. The panel weighs 6,500 pounds and is hanging 6 inches above the ground. The general contractor wants the panel set before the concrete pump arrives.
1. Can the laborer serve as your relay signal person? Explain what you would do before the panel is moved again.
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No. A relay signal person is still transmitting operational signals, so the person in that role must be a qualified signal person and must be able to see and be seen by the next person in the chain. The laborer has no qualification and no evaluated signal skill. The correct move is to hold the lift: give the stop signal, and because the panel is only 6 inches up, lower it to the ground and dog it. Then reposition a qualified signal person at the corner or move yourself to a point where you can see both the load and the operator. If a relay is unavoidable, brief the qualified relay on the exact standard signals, the stop signal, and the communication path. Until that is in place, do not move the panel.
2. The laborer suddenly gives the operator a “swing right” hand signal without your instruction. What is your immediate response, and what should the operator do?
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Give the stop signal at once-arm extended horizontally, palm down, moving back and forth-and transmit “all stop” if the radio works. The operator must stop on an unexpected stop signal even if it comes from someone who is not the designated signal person. Operational signals from an unauthorized worker must not be followed, but stop signals are always honored. After the load is stopped, lower it to a safe landing and dog it. Then explain to the laborer and operator that only the qualified signal person gives operational signals. If the laborer is to help, he must be trained, evaluated, and designated as a signal person; “just helping” is not a qualification.