Which of the following is a key safety protocol switchmen must follow?

A key safety protocol for switchmen is to always ensure that all personnel are clear of tracks before moving rail cars. This practice is essential for preventing accidents and ensuring the safety of both the workers and any bystanders. By making certain that no personnel are on or near the tracks, switchmen help to reduce the risk of injury or fatalities, as moving rail cars can pose significant danger.

The other options do not align with safety protocols. For instance, using a whistle to signal moving trains is important, but it is not as foundational to safety as ensuring people are clear of tracks. Likewise, safety goggles are crucial for eye protection and should always be worn to guard against debris and other hazards. Ignoring noise while signaling could lead to miscommunication and dangerous situations, making it critical for switchmen to pay attention and communicate effectively.