The new South Gate Rail service offers three daily return freight trains to Timaru, totalling up to 45 wagons in all, carrying up to 90 twenty-foot-equivalent containers (TEUs).
Also, on Saturday there will be a single 15-wagon return service.
Maersk and Hamburg Sud's departure from Timaru's PrimePort prompted more than 40 redundancies. The move followed Maersk's decision in May last year to quit using Port Chalmers for transhipment of its mainly empty containers, equating to about 44,000 movements.
Port Otago commercial manager Peter Brown said South Gate Rail was initiated by Port Otago, and KiwiRail had since committed and been contracted to provide the levels of rolling stock required.
"South Canterbury is a very rich hinterland. The product mix is similar to what we handle from Southland and Otago," Mr Brown said.
Port Otago has estimated recently it might pick up 10,000 containers out of South Canterbury.
"We would be happy with a figure like that," Mr Brown said.
Industry sources have said the level of patronage for Port Chalmers was highly dependent on how much Fonterra product ended up across the wharves of Lyttelton, Port of Christchurch.
Port Chalmers is the last South Island port of call for exporters, before three North Island calls, and therefore the only direct service to the east coast of North America for southern exporters.
However, industry sources caution that shipping rotation schedules are changing rapidly as shipping lines try to maximise vessel use and cut costs.
It was understood much of the new rail space might be for Fonterra product out of its Clandeboye plant, just north of Timaru, but Mr Brown declined to reveal likely patronage levels, citing commercial sensitivity.
"This [rail service] is not for any one entity, but is open to all," he said.
Similarly, he declined to reveal percentage targets of either the northbound or southbound wagons.
When asked if the service was in an initial "trial period", he said he was "hoping for it to become sustainable in the long term".
At present there was no coastal shipping service alternative, since a service ceased earlier this year, Mr Brown said.
For its full-year figures to June, released recently, Port Otago booked a 23% decline in container handling, being down 49,000 containers, from 221,000 the year before to 172,000.
