Be prepared to face a panel of 2-3 interviewers at the same time, don't worry they are nice and won't bite.
I suggest trying to find the "Interview Question Library" from Roads and Maritime Services if they let non employees see it. There are about 300 questions pooled that may be asked.
You can't prepare answers to all of the questions.
But you may be able to see a trend in the sort of questions you may be asked for the position you're applying for to plan ahead.
Answer questions with the STAR method and always with a relevant example.
Depending on the job, you may need to do a written test like writing a memo or a letter to a customer and it will always be the same day you do the face to face part of the interview.
Most RMS interviews seem to be between 3 to 8 questions long.
I believe less questions that are more complex and difficult to answer are for management upwards, and then a higher volume of questions of an easier nature in the customer service and non manager roles.