Know someone who sends his un licenced son to shift a 17 ton excavator on a low loader. Had a word with him once and said he doesn't bother chaining the machine on. didn't ask him why because already knew the answer. It takes up time!
So explained to him what can and will happen. But the lad knows best. Thinks that because its big and heavy it can't slide.
Spoke to his da and explained what was going on.
If the excavator slides off, crushes a car and kills people then who is too blame?
You are as culpable as the driver. When you drive any vehicle you, as the driver, accept full responsibility for using that vehicle in a safe condition and driving it in a safe manner. If you are driving a lorry with a load on board, even if you didn't load the cargo yourself, you are responsible for ensuring it is secured to the vehicle properly.
In law, if you know a person is not taking due care and attention when driving a vehicle, be it a laden lorry or a car that you know to be faulty or even just a driver who 'appears' to be not fit to drive, then you have a legal obligation to either challenge them directly, (in a non-aggressive manner), or to notify the authorities of your observations.
It is the same in the workplace. If you know someone is under the influence of drink or drugs then you must report them to your supervisor and they must take appropriate action to confirm or absolve them. People may not like me for this but I had occasion to do just this to a team member a few months ago. He turned up for work clearly drunk, (smelt on his breath when he spoke, not quite steady on his feet when he walked and slurred his speech when asked a question), so I had no option to report his condition to my supervisor. Turns out others had seen him entering work and reported to their supervisors who contacted our supervisor. He was interviewed with a representative present and suspended for the rest of the shift without pay and issued a written warning. The following week a similar incident occurred and again, as his team leader I was told he was on his way in and in a similar manner. Called him into the office and told him I would be reporting him again, which I did. He was summarily dismissed without notice by higher management.
Harsh? Not in my opinion. We are a maintenance team working on multi million pound, high speed production machinery. If we sign a maintenance sheet stating the machine is safe to run then we are the ones in the front line if a fault occurs because of something we didn't check and someone gets injured/killed. These same rules apply outside the workplace. If I knew someone was drunk and was going to attempt to drive home I would physically remove their keys or, if that was not possible for whatever reason, I would inform the police. I don't want someone's death on my conscience.
You know this guy doesn't chain down the excavator then you must report it to the authorities. You can do this anonymously if you prefer.