More than 60 years ago a train full of passengers plunged into the flooded Whangaehu River at Tangiwai but family members of the locomotive's driver have only just found closure.
On Christmas Eve in 1953, the rim of Mt Ruapehu's crater lake gave way and unleashed a lahar, taking out part of the Tangiwai bridge.
All but three carriages of the Wellington to Auckland train were hurled into the river moments later, killing 151 people.
Today a memorial was unveiled to remember the life-saving actions of two men who have not previously been singled out.
They were locomotive driver Charles Parker, who initiated an emergency brake, and locomotive fireman Lance Redman, who sanded the tracks to help the train brake faster.
Parker's granddaughter Denise Stanney said her family finally had closure after the service today.
She said for a long time people questioned Parker's actions that night.
"Today both of them were acknowledged for their bravery and it brings pride and it brings relief and quite a lot of emotion but also, a lot of closure."
Stanney said the trauma of the tragedy had had a significant impact on her family.
"They were so deeply affected that it was easier not to talk about him [Parker]."
She said Christmas was a sombre time growing up.
"Christmas Eve my dad was always very withdrawn.
"He got quite grumpy in the lead-up to that Christmas week and preferred to work rather than be at home where he would be alone with his thoughts."
Stanney travelled by steam train to the commemoration today.
"I found it quite emotional this morning once I could see the smoke going past the windows, it was almost like I was travelling their path."
Chairman of the Tangiwai Memorial Committee Bob Norling said Parker and Redman deserved to be honoured.
"If it [hadn't] been for these two men and what they did - the heroes of the night - for sure the whole train would've gone into the Whangaehu River," he said. Norling said the pair's actions stopped the last three carriages from going into the river.
"134 people survived that night, out of 286 that were on the train - so their contribution was fantastic."
Survivors of the disaster were also at today's service to remember the two men's actions.
One of them, John Mahy, was 15 years old when he boarded the train to return to his family home in Whakatane after spending time in Christchurch.
Less than an hour from the train reaching the bridge at Tangiwai, Mahy and his older sister were moved to the back carriages because a conductor noticed they were sitting in the wrong class.
"If you see a picture of the number two [second] carriage you'll realise just how much damage there was.
"There was just absolutely nothing left of it and I probably wouldn't be here today", he said.
Mahy said the service was moving.
"It does affect you to a certain degree, every Christmas Eve you kind of look at yourself in the mirror and think 'you're a lucky boy to be here today'."