Help:RBR.Driver HUD DVS
From TrainzOnline
RBR DVS (Dead Man) HUD
The DVS (Driver Vigilance System) or Dead Man system is a safeworking feature that ensures that the Driver of a train is in control. You press the F8 key when requested to clear a DVS event, not pressing the DVS button will eventually cause your train to activate an emergency stop. Do not randomly press the DVS key Nogura will become upset with you!
More information is available at the Razorback Railway in the help and driver documentation.
Razorback Railway :: Where you are the Driver!