Reidy says the return of freight services will be marked with celebrations in Christchurch and Kaikoura as the first train travels down the line.
Before the November 14, 2016 quake, one million tonnes of freight moved along the route every year.
"The limited re-opening will also take pressure off the inland route, which has been the main route to shift freight south since the earthquake," said Reidy.
"Even with the restrictions that will be in place, we still expect up to 2000 trucks a month will be taken off that road."
Meanwhile, hundreds of contractors continue working with heavy machinery to reopen State Highway One, which suffered major landslides in the quake.
The Government and NCTIR have repeatedly vowed to have it reopened by this Christmas.