It isn't a caveat, it is part of the Legislation.
of course it's a caveat:
"You
MUST NOT enter the box until your exit road or lane is clear.
Unless..." Isn't that the definition of a caveat?
The first entry for "Caveat" on Google says "a warning or
proviso of specific stipulations, conditions, or limitations." Maybe you and I use or understand English differently...
Thanks, but I liked keeping a good relationship with the Police where my Box was, and that is certainly not the way to do it.
I would have thought that warning them about behaviour likely to cause a train derailment or road-user fatality would be seen as a useful contribution to accident prevention.
On top of that, if as a signaller you had sat by and never flagged up people putting themselves at risk jumping warning lights then I wouldn't be surprised if a Coroner was to direct some harsh words at you at an inquest.
On second thoughts, maybe you should have talked to the local Fire Brigade (now Fire and Rescue?) Ours seem to be quite heavily into accident prevention now.