The inaugural service from Christchurch is due at the Dunedin station at 4.45pm and the train’s owner, Rail and Tourism Group, is encouraged by how quickly tickets were snapped up.
Group chief executive Paul Jackson said excitement was building ahead of the trip.
The Mainlander’s journey today is to be followed by a trip to Invercargill tomorrow, back to Dunedin on Thursday and on to Christchurch on Friday.
Some passengers may mix things up with an excursion through the Taieri Gorge on Thursday.
Mr Jackson said 520 passenger movements had been scheduled over the first four days of operation - "a solid start to the Mainlander, so we are feeling very positive".
Bookings were sold within five weeks of the Mainlander service being announced, he said.
The group has yet to announce precisely what might be planned beyond this week, but the intention is to prove a business case for the Mainland Rail project over the coming months.
"This is a conversation that we are delighted to have with the various regional councils who see benefit," Mr Jackson said.
The company would evaluate indicators such as passenger numbers, customer satisfaction and service punctuality.
Mr Jackson was also involved in an initiative to get an "events express" train running out of Christchurch, ideally in time for the April opening of the Te Kaha stadium.
Mr Jackson appeared to confirm Dunedin was in the frame for events travel in future.
"Watch this space for an imminent exciting announcement, as we look to schedule some trips with Dunedin as the point of origin."
