The Melling line has re-opened after one of KiwiRail's new Matangi trains failed to stop and ploughed into a safety buffer.
The 7.50am train with nine passengers, one driver, and a guard hit the concrete barrier at a low speed, KiwiRail spokeswoman Kimberley Brady said.
Alicetown man Phil Dunsford was on the train when it came to an ''almighty halt'' with a ''bang, crash'' sound at Melling.
He now had a sore shoulder which he suspected was mild whiplash.
One woman was thrown to the ground but escaped serious injury. Another passenger had a cup of coffee thrown from his hand.
Mr Dunsford said he was disappointed train staff did not check on the wellbeing of passengers.
Andrea Lynch was at the station waiting to board.
''I was standing at the point where the train doors normally end up but sometimes the driver will take the train right to the end of the track and when the train kept going.
''I thought that this was the case, but then a second later I realised that the train was not slowing down at all and I looked up to the end of the line and saw the train hit the concrete barrier and was shunted back.
''I also saw a couple of people on the train being jolted forward in their seats.
''When I went to the front of the train I saw that the concrete barrier had been moved quite a bit and the area surrounding it had sustained a wee bit of damage, too.
''Everyone was in a bit of shock not quite believing what had just happened but the train staff were great and kept us informed while trying to sort out the situation with Tranz Metro.''
The accident is being blamed on a mechanical fault.
The Transport Accident Investigation Commission and KiwiRail would both investigate the accident.
It was not clear what the mechanical fault was.
All Melling trains were replaced by buses to Petone until the accident site was cleared, and the safety barrier repaired.
Belmont resident Warwick Annear said by the time he got to the station to catch the train the driver was sitting in a car, ''obviously upset''.
The buffer stop had been shunted perhaps half a metre, ''and that's a big block of concrete''.
The train had not been de-railed, but there was quite a bit of damage to the coupling at the front, Mr Annear said.
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