What distinguishes Rule 409 from Rule 410?

The distinction between Rule 409 and Rule 410 is primarily based on the type of signaling that is utilized. Rule 409 is specifically designed for operations that involve fixed automatic block signals. This means that the movement and control of trains under Rule 409 rely on signals that are permanently placed along the tracks and automatically indicate the status of the block ahead.

In contrast, Rule 410 may govern other operational aspects that do not strictly involve or depend on fixed automatic block signals. The focus on fixed signals in Rule 409 emphasizes the structured and automated nature of train movements in certain scenarios, making it crucial for ensuring safety and efficiency in train operations.

The context of the other options highlights key differences that may exist in train operations but do not define the unique characteristics that distinguish Rules 409 and 410 specifically. Therefore, recognizing the role of fixed automatic block signals under Rule 409 is essential for understanding the operational protocols that come into play in scenarios governed by this rule.