Which type of signal is specifically mentioned as potentiate to interference by whistle blowing?

The concept of signals in the context of train operations is critically important for maintaining safety and ensuring proper communication on the tracks. Among the types of signals mentioned, necessary signals are specifically designed to convey critical information that the train must adhere to, and their effectiveness can be undermined by external noise, such as whistle blowing.

Whistle blowing often occurs in various situations, including when trains are approaching crossings or during emergency signals. If a necessary signal is compromised by the noise generated from whistle blowing, it could potentially lead to confusion for the train operators or affect their ability to respond appropriately. This highlights the significance of ensuring that necessary signals are clear and free from interference to keep operations safe and efficient.

In contrast, while warning signals, entry signals, and proceed signals are also crucial for train operations, they do not specifically face the same level of interference risk that is pertinent to necessary signals. Necessary signals are critical for compliance and adherence to operational safety protocols, which is why they are distinctly highlighted in this context. Ensuring their clarity and effectiveness is paramount to prevent miscommunication that can lead to hazardous situations on the railway.