A lot of heavy machinery or transport vehicles, like locomotives, use a fail safe system called a dead man's switch.
A dead man's switch is a switch that stops a piece of machinery or vehicle automatically if it is in danger of causing significant danger. The switch is engaged if there is no response from an engineer or operator, assuming that the responsible party is incapacitated. There are some switches that can be engaged from an outside source as well.
It is called a dead man's switch because the fear that the death of an operator could leave a machine or vehicle unmanned.
Dead man's switches have even made there way into many people's back yards as well. The button on that chain saw that unlocks the trigger for you to turn the saw on, that is a form of dead man's switch.