When is an Interlocking Appliance considered blocked?

An Interlocking Appliance is considered blocked when a device is applied to prevent its operation. This means that the interlocking system is intentionally held in a state that does not allow normal traffic flow or switching operations, typically to ensure safety while a situation is being managed or a procedure is being followed. Blocking is a deliberate action taken to control the flow of train movements and ensure that safety protocols are strictly adhered to.

The other scenarios outlined do not directly relate to the functionality or state of being blocked. For instance, when a train is using the track, the interlocking system is actively in use and operational, not blocked. Scheduled maintenance refers to a routine procedure meant to ensure systems function well, and during such times, the appliance is not necessarily considered blocked but rather undergoing checks. Likewise, when under inspection by a technician, it is about assessing the system rather than indicating a blockage.