Hi Willpilbeam,
Congratulation on passing the application & ability test. To answer your question on scoring, you will never know. It's either a case of going through to the next stage or not going any further. Keep at it, it's worth it.
Advice for the interview & to quote from
@Horizon22 "Safety is obviously key but think about other skills like dealing with emergency situations, working with others, the importance of clear communication, prioritising tasks and so on".
Something that might be worth thinking about before the interview. Take some notes of what is around the signal box. Viewing from the station platform, not trespassing. (google maps is your friend)
Good luck.