The northern rail line is closed after a freight train derailment on Monday.
The incident comes less than three months after a $200 million upgrade.
The train derailed between Topuni and Kaiwaka.
A Kiwirail spokesperson says repairs are progressing well and it is hoped that the line will reopen in time for the next scheduled service next Tuesday (April 6).
Meanwhile, a resident whose property backs onto the line sent a photo to the Mahurangi Matters of concrete sleepers that are yet to be installed.
They say the sleepers have been sitting there since the line reopened in mid-January.
The line had been closed for upgrades for eight months.
Asked if the derailment was due to old sleepers, which had not been replaced before the reopening, Kiwirail was tight-lipped.
“It is still being investigated and it is premature to speculate on the cause,” the spokesperson says.
Last year, Kiwirail said the new line would be “fit for use for generations”.