Line 14 entering Chatelet-Les Halles
This is the only underground train in Paris that just runs by itself with not a single conductor on board.
So when the other lines stop running during a strike the chances are that this line will continue to run!
Note the glass doors on the two opposing platforms that only open when the train comes to a halt.
This is a feature that is present only in Line 14 but there is talk of extending it to the other lines in view of occasional suicide attempts and cases of lunatics pushing innocent people off the platform.