What type of signals are primarily used by a signal person in crane operations?

In crane operations, a signal person is responsible for directing the movement of the crane and the load being lifted to ensure safety and efficiency. The primary types of signals used during these operations are visual and audible signals.

Visual signals often include hand gestures or flags that are clearly visible to the crane operator, ensuring that instructions can be communicated effectively even from a distance. These signals are crucial in situations where noise levels are high, as they allow for safe communication without relying solely on hearing.

Audible signals, on the other hand, might include specific sounds or horn signals that can quickly alert the operator to start or stop movements, especially in scenarios where the view between the operator and the signal person might be obstructed.

The other options like only verbal commands, gesture-based signals only, and written instructions do not fully encompass the range of signals necessary for safe crane operations. Relying solely on verbal commands or one type of signaling can lead to miscommunication and increased risk during lifting operations. Thus, the combination of both visual and audible signals is essential for clarity and safety in crane maneuvering, making this the correct approach.