"Two work gangs, along with contractors who provided plant, worked on the line over the weekend when there were no trains running and replaced around 300 sleepers," Sivapakkiam said.
"Installing the concrete sleepers and improving the track formation will mean the track can carry heavier axle loads and increase the line's reliability."
Work on the line will continue over coming months at a number of sites between the junction at Aramoho and Castlecliff.
The project is expected to be completed in mid-2020.
Approximately 300 wooden sleepers have been replaced with concrete ones which will mean the track can carry heavier axle loads and increase the line's reliability. Photo / Mark Seconi