I have attended an assessment day for a conductor vacancy with this TOC before. In the group exercise we were given an example of a situation a conductor could face and we had to work out how we would deal with the scenario effectively. The assessors were more keen on how we worked together than the actual result of our actions. Therefore you and the other candidates are best working together and supporting each other. Don't view it as a fight to the death for the role, consider that if you all work together it will benefit all and you could all be offered the job!
With the interview be prepared to answer lots of customer-service based questions and have examples backing up where you have demonstrated the necessary skills required for the role. Use the STAR technique to answer the questions where you can.
Also thoroughly research the company so you can show them why you wish to join this particular TOC.
Best of luck!