Few "social" things mentioned here. By "social" I mean at work, rather than your own social life outside work.
For example, the awkward situations like when you know someone regularly has a skinful on their final day off. But you know them, you get on with them. What do you do? "Grass" or is it nothing to do with you?
(Honest answers as to what you'd actually do wanted, not what you think someone judging you would want! I've known this situation twice. They weren't my colleagues, but were people I got on well with and drank with)
Being blunt, if they are having a skin full and then driving a train the next day they are a danger to themselves and others.
Turning a blind eye to it doesn’t do anyone any favours and could lead to terrible consequences.
I understand that you don’t want to cost anyone their job, but at the end of the day it isn’t you costing them the job, it is themselves. And if they truly respected and appreciated the job they would make sure to be fit for work.
Easier said that done but I’d like to think I’d be having a chat with them face to face and making sure it doesn’t happen again, and if they turned up for duty I’d report them tbh.
Imagine how bad you would feel if he was involved in a safety critical incident and injuries or death came from it and you knew all along he was still under the influence.
Also just to add to that, If I found out myself or any of my family and friends had been on that drivers train after a heavy drinking session I’d be fuming.