Two train units derailed last month along the Kapiti Coast may be out of action for months.
Flooding and debris caused road and rail issues on State Highway 1 near Paekākāriki on 17 August. Photo: Waka Kotahi / NZTA Wellington
A landslip on the coast near Paekākāriki on August 17 caused a commuter train with 80 passengers to come off the tracks. No one was injured in the derailing.
A Metlink report on the incident showed several parts of the train units were damaged, and may be out of service for a "considerable length of time".
In previous events where units have been damaged, it has taken up to six months for repairs to be completed, due to delays with parts and labour availability.
While a full assessment of cost has not been established, the report is estimating it will cost between $300,000 and $500,000.
The report also outlines the cause of the incident.
A large volume of rain caused stormwater to collect debris from higher up the escarpment, wiping out a section of track access walkway as it swept down to a stormwater culvert and blocking it. The excess debris then spilled out over the track.
The site of the landslip, which along the Kapiti Coast is among a series of steep slopes, was not considered at high risk.
The slope site was last assessed in October 2019, and was rated medium risk, and therefore not meeting Kiwirail's assessment criteria to be strengthened.
The Wellington Metro Upgrade Programme has $10 million allocated to remedy high-risk slopes along the wider area.
The Transport Accident Investigation Commission launched an inquiry into the incident, which will take around 18 months.