The Pike River mining tragedy and Christchurch earthquakes have been a double-edged sword for KiwiRail's freight business.
Figures obtained under the Official Information Act show freight destined for Christchurch dropped more than 10% in the first four months of the year.
Slightly more than one million tonnes of freight was moved to Christchurch by KiwiRail in the first four months of the year - a decrease of 13% on the same period a year earlier.
KiwiRail says coal tonnage was down significantly as a result of the Pike River mine tragedy, in which 29 men died, and limited production from another West Coast mine, Spring Creek, while a safety review was conducted.
But when coal is excluded, net tonnage to Christchurch actually increased by 9%.
It is believed re-supplying Christchurch following the September and February quakes is a major part of the increase.
Figures also show the port of Timaru benefited from quake damage to the port of Lyttelton, with its rail tonnage to Christchurch up 179% in March.