I recently visited a small mechanical box using traditional AB which controls two standard lifting barrier crossings, both operated through the lever frame. One of the crossings is on-demand, with the barriers normally lowered, and opened only when a buzzer signal is received by the signaller.
Since the visit I have been informed that the box is switched out on a fairly regular basis. As some of the signals are semaphores, they can only be cleared through operation of the frame. As I understand it, for the box to be switched out, the running line signals have to be set in the clear position, effectively locking both level crossings. I am assuming that in the absence of a full signaller, a crossing attendant is provided to operate the barriers, as there does not appear to be any provision for remote operation. Is he/she authorised to operate the signal levers under instruction from the signaller at the box at the start of the (extended) section or will there be some form of switching to override the locking?
Alan