How is the hand signal for 'proceed' indicated?

The hand signal for 'proceed' is indicated by raising and lowering the hand vertically. This motion serves as a clear and recognizable signal to train operators or crew members, indicating that they are authorized to move forward. The vertical motion is distinct and creates a noticeable signal that stands out against the backdrop of the environment, improving visibility and comprehension.

In this context, raising the hand signals the start of movement, while lowering it signifies readiness to proceed without any obstructions or issues present. This method of signaling is standardized within railway operations to ensure safety and effective communication among personnel.

Other options may suggest alternative signaling methods, but they do not align with the established protocol for indicating 'proceed.' For instance, signaling swung horizontally or in a circular motion has different meanings, such as indicating 'stop' or other operational commands, which might lead to confusion if used incorrectly.