File pic Photo: RNZ / Samuel Rillstone
KiwiRail staff were "overworked and under supported" when a railway maintenance machine derailed at an Auckland tunnel, the Transport Accident Investigation Commission (TAIC) says.
Three linked tamper machines came off the rails in Purewa Tunnel shortly after midnight on 9 November, 2023 after a section of track had been removed.
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.
None of the crew or any track workers were injured, but the machine was badly damaged.
The TAIC report, released on Friday, explained how train controllers and track officers were kept in the dark about a gap in the railway.
The train controller, the worksite's rail protection officer for the worksite and four train crew members were all unaware of the gap.The report said the driver of the lead machine saw the missing rails but could not stop in time.
"[The tamper] was unable to stop before driving off the end of the track and into ballast, where it travelled for 16.4 metres before stopping. The rear two machines were able to stop and remain on the track."
Staff aware of the missing track did not properly communicate it to key personnel.
"Safety-critical information about the removal of the track within the project area was not provided to the track protection team because the key staff who were responsible were absent," the report said.
"Key staff were unsupported while working in safety-critical roles and had very high work volumes."
In a statement, TAIC acting chief investigator of accidents Louise Cook said 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.
"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."
The commission recommended KiwiRail review and improve its process for authorising rail movements within worksites to ensure the safe movement of all rail traffic and personnel within protected work areas.
The recommendations included the "verification of track integrity and the sharing of and access to safety-critical information".
KiwiRail has also been called to review and improve its rules and procedures relating to track maintenance work.
Lastly, it was being asked to review its national project management structure to ensure there was sufficient oversight of and ongoing support for all project staff.
KiwiRail accepted all of the commission's recommendations.
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