I'm not 100% sure to be honest - might be some similar questions that you had in the OPC interview.
From browsing here I'd guess Customer Service, Conflict, emergency etc - and possibly more general ones like what you think the role is about, why you'd be good.
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Also, not a train related interview but a few recent ones I've have had asked questions about a time you've made a mistake, things have gone wrong etc.
They basically just want to see that you have reflected and learned on that experience and how you handled unexpected things happening.
Good luck for tomorrow - hopefully someone that has been through one will post something more useful soon.