I have already done the assessments for a trainee train driver - do i still need to do them for a train manager role?

Good afternoon and thank you for your question!
You will need to take another assessment. Many operational and competency roles have assessments, and they are different from one another, to make them suited to the skills and behaviours needed for the core responsibilities. The good news is, there may be some crossover regarding Drivers and Train Managers assessment, due to the safety critical aspects of both, so you may find if you did well for one, you may do well for the other! Good luck :)