Just to interject, that isn't strictly right.
You can only pass a *controlled* signal (no other type) (under AB or TCB) when it has been confirmed that the controlling signalbox is closed.
You can only pass an IB signal under your own authority if you are unable to contact the controlling signaller by any means of communication (SPT defective, no other nearby working phones, no GSMR/NRN/mobile etc).
You can only pass a *controlled* signal (no other type) (under AB or TCB) when it has been confirmed that the controlling signalbox is closed.
You can only pass an IB signal under your own authority if you are unable to contact the controlling signaller by any means of communication (SPT defective, no other nearby working phones, no GSMR/NRN/mobile etc).
