The Transport Accident Investigation Commission (TAIC) says rules and procedures failed to prevent a derailment in Auckland’s Purewa tunnel because critical staff were overloaded, unsupported, and unaware of missing track.

TAIC’s final report, published today, investigates how three linked tamper machines* came to derail inside the Purewa tunnel in Auckland just after midnight on 9 October 2023. They had been authorised to pass through the tunnel, but rails and sleepers inside had been removed.

Neither train control, nor the Rail Protection Officer for the worksite, nor any of the four train crew members knew about the gap.

The driver of the lead machine saw the missing rails but couldn’t stop in time. The machine ran off the end of the track and ploughed through 16 metres of ballast before stopping. None of the crew or any track workers were injured, but the machine was badly damaged.

TAIC Acting Chief Investigator of Accidents, Louise Cook, says the accident was preventable.

“There were no engineering protections in place — nothing automatic to stop a train or to warn that rails weren’t in place. Engineering controls are more reliable than rules and procedures that govern human behaviour. We’ve recommended KiwiRail require such protections wherever tracks are impassable — like in the Purewa Tunnel that night, where the track had been removed for repairs.”

The report says staff who knew about the missing track hadn’t properly communicated about it. Train controllers and the worksite’s Rail Protection Officer were unaware the track was missing.

“Authorisation for the rail movement relied on people applying rules and procedures. But those failed because safety-critical staff were overworked, and the people who knew the track was gone were unavailable and hadn’t communicated crucial information,” says Ms Cook.

“KiwiRail needs to improve how it authorises rail vehicle movements through worksites. It’s already working on this, and it needs to follow through.”

The Commission also found that high workloads, lack of support for key staff, and perceived time pressures with project requirements likely led to oversights and errors contributing to the incident.

“KiwiRail must ensure safety-critical workers have reasonable workloads and proper support.”

KiwiRail has accepted all of the Commission's recommendations.

The full report, RO-2023-105: Derailment of Tamper 703, Purewa tunnel, Auckland, will be available online www.taic.org.nz

* A tamper is a railway maintenance machine that lifts and aligns track while compacting the ballast beneath the sleepers, to create a smoother path for trains.

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