What must be used to prevent movements on a track that is "on hold"?

When a track is designated as "on hold," it is crucial to implement effective measures to ensure that there are no movements on that track. Alternate blocking devices serve this purpose by providing a physical means to prevent trains from inadvertently accessing the track. These devices can include a variety of tools, such as derails or lockout mechanisms that ensure that no movement can occur until the track is cleared for use. This method is not only more reliable than verbal instructions, barriers, or signage, but it also adheres to industry best practices for safety management, ensuring that all personnel are protected and that operations can proceed safely when the hold is lifted.

Using verbal instructions alone lacks the physical assurance required for optimal safety, as it relies on human communication which can be misinterpreted or overlooked. Barriers at station entrances may restrict access, but they do not fully prevent movements from occurring on the track itself. Emergency signage can provide warnings and information but does not actively prevent movements, making it inadequate for securing a track that is "on hold." Thus, alternate blocking devices are the most effective solution for maintaining safety during a hold situation on the track.