[dharmon]

While unfortunately not common in trains across the world, this idea is used in other safety-critical applications.

The one that comes to mind is using defribulators. If you had a good CPR / EFR instructor, they will emphasize not just calling "clear" (like on TV), but physically sweeping your hands over the body head to toe while saying "all clear".

I did my training with 3 guys who collectively had about 60 years of EMT experience in New York City. Like most students, I assume, I sort of half-assed the sweep and was about to push the button. One of the guys grabbed my arm, looked at me, and said "Learn to do it correctly now, cause if you ever have to do it for real when shit is crazy and your heart is beating like mad, it can make the difference between helping one injured person vs creating a second one."

Clearly the lesson stuck with me. :)