I was given a task before the interview date to solve and present on the day interview. I was also given an on the spot task to solve for 5 mins, it was emphasised that the correct answer is not what they are looking for but one's reasoning behind how you arrived at such solution. Safety questions, question about what projects they are working on.

very fair interview, questions were based on how you behave and respond in certain situations that are difficult or high pressure etc, and also focused a lot about safety which is crucial for Network Rail make sure you read and understand their safety material online very well.