Which type of derail is characterized as being permanently affixed to the rail?

The type of derail that is permanently affixed to the rail is known as a permanent derail. This device is designed to remain in a fixed position on the track, serving as a safety measure to redirect rolling stock away from tracks that are not in service or towards a safe location in case of an emergency.

Permanent derails are typically installed in locations where regular track maintenance occurs or at yard entrances to prevent unauthorized trains from entering certain areas. Their static nature ensures that they provide a reliable safety feature without the risks associated with the potential misuse or removal that can occur with portable versions.

In contrast, portable derails are intended for temporary use and can be moved as necessary, while hand-operated and motor-powered derails are often designed for situations where adjustments need to be made on a more regular basis. Understanding how permanent derails function and their specific applications can be crucial for ensuring safety in rail operations.