From the aforesaid wordings it would imply that the gate is to be closed whenever the workers are inside or outside of the secured area. I am sure it did not mean that the gate cannot be opened at certain times or under certain circumstances.
This brings me to the next sign which could well prove to be a strong contender for greater conciseness to say what was meant to be conveyed all along when saying that 'gates must be closed at all times' :-
It is refreshing to have read this different take on the gate signage.
Related posts on words in public places:
* No Letting Up On Words
