dead-man's vigilance device

A hybrid between a dead man's switch and a vigilance control device is a dead-man's vigilance device.

A dead-man's vigilance device is a railroad safety device that operates in the case of incapacitation of the engineer.

If no action is taken an alarm sounds, and the tram comes to a complete standstill if it is ignored (see dead-man's vigilance device).

The dead-man's vigilance device was developed to detect this condition by requiring that the dead-man's device be released momentarily and re-applied at timed intervals.

But as soon as the management discovered this, their reaction was "vigilance control," actually a dead-man's vigilance device, and hence the notice in the cab "Vigilance control now fitted, release and reapply every minute, if an alarm sounds, release and reapply immediately."