Hi mate it's tricky to give you too much advice without knowing what they knocked you back on but the advice given above is spot on!
There are many big important things to get across in the managers interview but it's important not to forget the little things as well such as don't sit until you are invited to, a good handshake and always maintain eye contact. It's also worth remembering you are effectively being watched the moment you enter the building so it's best to treat the entire time you are there like they are sat alongside you.
In the interview itself make sure that you are positive with your replies, for example if the ask you a question avoid saying things like erm,possibly or maybe etc etc etc they want to know what you are telling them is fact not guesswork. When they ask you about a certain scenario make sure you tell them about what YOU did, so many go off on tangents about what happened as a group for example but that is not what they are asking.
Using the STAR format is always a good way to go if that has ever been put across to you?. Ensure you have done your research on the company that you are applying to, knowing things like the franchise details,routes they cover and the traction they work are the most important bits but you can never go wrong with knowing how many employees they have and what the company values are etc.
Be honest is probably the most important thing out of the entire interview, If you don't understand a question ASK, I f you don't have an example for a question they have asked just tell them! any decent manager will find another way to ask the question and it may help you use a scenario you didn't even think was initially relevant!. Do not try and wing a scenario, these guys are well trained and will spot a lie a mile off a, once there is a doubt about your integrity you may as well forget it. Remember there is no shame in not being involved in an emergency situation before, it's not something we have all done and you wouldn't of got that far if something like that was a truly defining factor in whether you get the job.
and remember the reason why you want to be a train driver for the company you are applying to. you'd be surprised how many people fail for messing up on that question alone and it's arguably the most important question out of the lot.
Good luck mate.