The Wellington commuter train that smashed into a concrete stop block at Khandallah in June passed a red departure signal, its emergency brake came on in the same second, and a trackside device meant to trip the brakes automatically failed to engage, according to an interim report published this morning by the Transport Accident Investigation Commission.
The interim report, released on 15 October, sets out a second-by-second timeline of the crash on the Johnsonville Line on the evening of Saturday 6 June. It stops short of explaining why any of it happened. The commission says it is still verifying evidence and will not reach findings until a final report, which could be another year or more away.
What the report does establish is that the trouble started well before the train reached the stop block. At 6.50pm, as the two-car Matangi unit was heading north towards Johnsonville and approaching Khandallah Station, the signalling system registered what rail engineers call a dropped track. That is the term for the system deciding a stretch of rail is occupied when it may not be. It can be caused by a broken rail, a faulty electrical connection or even excess moisture on the track.
Because the system now believed there were two trains in the same section, an error message appeared on the train controller’s screen at the Wellington Regional Operations Centre in Upper Hutt. “The error message was a visual warning only and did not generate an audible alarm to alert the train controller,” the report says. It stayed on screen for 25 seconds and then vanished once the train entered the station, because the system no longer saw two trains in one section. But the phantom occupation south of Khandallah remained, and the interlocking did what it is designed to do. It held every signal guarding that section at red.
The Johnsonville Line was running in automatic mode at the time, meaning signals and points were being changed by the control system without a controller stepping in.
The train carried on to Johnsonville, where the driver walked to the cab at the other end for the return trip to Wellington. It left on schedule at about 6.58pm, stopped at Raroa, then passed a yellow-over-red caution signal and pulled into Khandallah’s southbound platform at about 7.05pm. Because of the dropped track, the departure signal at the southern end of the platform was held at red, and the points ahead of the train were automatically set for the runaway line, a short dead-end spur fitted with a concrete block that is there precisely to catch a train that goes past a red signal before it can run onto the single line and meet another train coming the other way.
The train manager checked the doors were clear, pressed the all-close and right-of-way buttons, and a green light and audible tone in the driver’s cab confirmed the train was ready to go. Power was applied and increased over the next eight seconds. At 7.06pm and 12 seconds the train passed the red departure signal. In the same second the emergency brake was activated. Two seconds later the train ran over a fixed train stop on the runaway line, a lineside device that is supposed to knock a trip lever on the train and apply the brakes. The lever did not activate. Two seconds after that the pantograph came off the overhead wire, the train lost all power, and it hit the stop block at 33 kilometres an hour.
Both the driver and the train manager were hurt badly enough to need hospital treatment, and four of the eight passengers suffered minor injuries. The leading car, trailer unit FT5275, was substantially damaged. The report also records that no emergency alert reached train control after the collision. Passengers and people in nearby homes rang emergency services, and it was the emergency services who then told train control what had happened.
TAIC’s Chief Investigator of Accidents, Louise Cook, said in the commission’s media release that investigators had so far established the train was diverted because the signalling system detected the track ahead was occupied, and that the points were set to send it onto the runaway line to prevent a collision with other traffic. “We are still verifying evidence and pursuing several wider lines of inquiry, including why the red danger signal was passed,” she said.
Cook was careful to stress the limits of the document. “The commission at this stage hasn’t made findings or identified safety issues,” she told RNZ. She said she could not yet confirm whether the track had genuinely been occupied or whether the system had thrown up a false stop, and that understanding why the driver went through the red was part of the ongoing inquiry. “Once that inquiry is complete, the final report will set out findings, safety issues and, where appropriate, recommendations to avoid similar accidents in the future,” she said. RNZ reported that the inquiry could take between 18 months and two years from the date of the crash.
The report’s own description of its purpose is blunt about this. Interim reports present the facts established so far, are issued when inquiries are complex or attract heightened public interest, and the final report may differ from them. The commission’s governing law also directs it to find circumstances and causes with a view to preventing repeats rather than to blame anyone, and its findings cannot be used in criminal, civil or regulatory proceedings.
Even so, the interim report lays out several threads the final report will have to pull together. There is the dropped track itself and what caused it. There is the fact that the only warning to the controller was a silent message that disappeared after 25 seconds, while the consequences of it persisted. There is the question of why a driver who had worked for Transdev since 2016 and held full and current certification passed a red signal moments after being given right of way by the train manager. There is the trip lever that was supposed to be the last automatic line of defence and did not work. And there is the silence from the train after the crash, which left it to passengers and neighbours to raise the alarm.
The commission has gathered the train’s Tranzlog data recorder, signal logs, CCTV, mobile phone records, track and infrastructure records, train control voice recordings and system replays, and has interviewed the driver, the train controller, witnesses and passengers. A draft of the interim report went to seven interested parties on 26 August. Four made detailed submissions, one had no comment and two did not reply. The final version was approved for publication on 23 September.
In the days after the crash, as NEWS WIRE reported at the time, officials leaned heavily on the fact that the runaway line and its stop block, installed during maintenance works in April 2025, had done exactly what they were built for and kept a train off the single line. That remains true. The interim report confirms the diversion worked as designed. What it adds is that one of the other layers of protection, the fixed train stop and trip lever, did not, and that the train was still doing 33 kilometres an hour when the concrete finally stopped it.
The Johnsonville Line was closed for eleven days while KiwiRail repaired broken rail, repositioned track that had shifted in the impact and reinstated the overhead wires, with Transdev running test trains before passenger services resumed on 17 June. The line carries around 3,000 passengers on a normal weekday along roughly 10 kilometres of single track through seven tunnels, climbing more than 150 metres from the city to the northern suburbs.
For the people on board train 9379 that night, and for the thousands who ride the line each day, the uncomfortable position is that four months on they now know exactly what happened, almost to the second, and still do not know why. Was the dropped track a real fault or a false alarm? Should a silent, vanishing error message be enough warning for a controller? Why did the trip lever fail, and should a train on a steep suburban line have more than one automatic backstop? Have your say in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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