I would like to add my two pence here that every question is related to what a train driver could come across, the way to tackle these is to always think to yourself how is this related to the role of a train driver and what would a train driver need to do. I have to agree with twotwo here in the sense that it shouldn’t matter how a question is asked, if you think like the above you should always be fine. Any emergency type of question if you compare to the role of a train driver taking control, taking the lead, remaining calm, asserting authority and many more should all be things that are covered in your answer, if your answer is not able to demonstrate that then another is certainly needed that can.
I believe researching extensively what the role of a train driver is will put you in good stead for the MMI and that is what gets people through regardless of how questions are asked wether obvious prompting words are used or not.
As far as I know all the 6 question criteria's have many many different formats and different candidates will be asked different ones, the whole point of the situational judgment exercise that is done prior is to determine which questions you are asked and perhaps even how the examiner asks you it. For all you know perhaps you selected strong responses in the situational judgment that proved you to be someone who takes a lead in things so the interviewer thought no need to word it in the question as it’s in your personality/method of thinking anyway so would show in your response.
Main thing really is know the role of a train driver inside out and think “what would a train driver do” and you can’t go far wrong as THAT’S the answer their expecting. (There’s a thought I should invest in some T-shirts with the lettering WWATDD)