"I ran and pushed him out of the way and when I turned around it just snapped me in half."
Mr Healey woke up in a hospital ward. "I tried to get out of bed and I fell flat on my face."
The steel had crushed his vertebrae, damaged his spinal cord and he'd lost the use of his legs. He had two spinal operations and says his doctors told him he'd never be able to walk again.
But Mr Healey wasn't having a bar of it, and he set his mind to walking again.
He found a therapist who used hypnotism to help him visualise his recovery.
"I don't know if you know what endorphins are - when I first heard that I thought they were dolphins - she said she was gonna get me to work with endorphins. I said 'great! I love the ocean'."
Under hypnosis, Mr Healey said he was able to imagine he was no longer paralysed.
"It sounds a bit weird but it worked."
In the following two years he slowly got back on his feet. "My first 10m took me 20 minutes - now it takes me 10 seconds," he said.
Over that time he was walking about 42km a day from his home in Botany to Auckland City Hospital and back - a trek that took him 18 to 20 hours.
After about six months someone pointed out to him that he was walking a marathon a day. "I must have walked that route about 290 times in just over a year. I had no job, but I wasn't a deadbeat bum. I was just taking time to reconnect my life."
Nowadays, he walks around his Panmure workplace, where he's a regional manager for a freight company, with a spring in his step and no sign of a limp.
This is despite the fact that he has no feeling from the chest down on the left side of his body, and about 30 per cent in the right.
Mr Healey joked that not feeling his legs was awesome, because it didn't hurt to run a marathon. "I blow nerves and tendons ... but I don't experience the pain."
The first marathon he ran was "to stick it to the man" who said he would never walk again. Now he's run marathons all over New Zealand and in Australia and Hawaii. He's also run the New York marathon twice, and is heading back there (and to Boston) next year with a group of 50 runners.
In his spare time he helps people to get fit, and usually takes a team of runners to the marathons he competes in. "It's less of a race and more of a running party."
In New York last year he spent 10 hours on the course running back and forth helping people get across the line.
This year he's got a group of 15 ready to go for the Auckland Marathon.
He doesn't charge for the fitness sessions, boot camps or running groups he holds at Barry Curtis Park in Flat Bush - he says changing people's lives is just his buzz, and he's been doing it for seven years.
"I've got some crazy cross-fitters, some iron people, some young Maori kids, some newlyweds, I have the broken people who've had gastro, heart disease or cancer. It's like the broken fit club. I've got the overweight, the no-hopers, I've got the 'my partner's left me' people. They're all there."
His journey - from learning he couldn't walk and falling into depression, to running marathons like the one on Sunday - was a long one, and Mr Healey says in some ways the accident was a blessing.
"It kind of sounds funny, because it almost killed me, but that accident actually saved me."
By completing the new 12km Traverse race at the Auckland Marathon, Paul Martin hopes to help raise more than $10,000 for Youthline, a charity he believes his daughter Danielle would have benefited from. Danielle committed suicide in April last year, aged 23.
"There were a number of causes that my wife and I looked at," he said. "We thought kids can face a large group of issues and we liked the idea of Youthline."
Mr Martin, an information systems manager, has raised nearly $6000 for Youthline and hopes that by walking the traverse, he can hit $10,000.
He weighed 175kg, has so far shed 10kg and hopes his improved fitness will enable him to lose even more. To donate, visit fundraiseonline.co.nz/Raise4Dani2015/
Youthline: 0800 376 633
In his mum's footsteps
When Elliott Roe lines up for his debut marathon on Sunday he will be treading a well-worn family path as the son of former Boston and New York Marathon winner Allison Roe.
Mr Roe, 22, an aircraft engineer, says he had little interest in running, but made a New Year resolution to do the marathon.
He started training five months ago and wisely sought his mother's advice.
"She's written my training plan, gives me tips all the time, it is like having a fulltime coach."
Despite admitting that the running genes "skipped me", Mr Roe, who is raising funds for Sir Edmund Hillary's Himalayan Trust in Nepal, initially set an ambitious goal of a sub-three hour marathon. But niggling injuries have hampered his preparation and the 80km a week training has taken its toll.
So what is the best piece of advice mum has given?
"It is probably the one I didn't listen to, which was to take it easy in training."
For marathon addict Mike Smith, completing the Auckland Marathon will bring an end to his global quest of running a marathon on all seven continents.
The 57-year-old American started running marathons 20 years ago and it was after completing a 42km race in all 50 US states that he decided to set himself a new target.
"I ran the Antarctica Marathon in early 2002 and then it occurred to me that it would be great if I could run a marathon on every continent," Mr Smith said.
He has since ticked off the Dublin Marathon (Ireland), Comrades (South Africa), Santiago (Chile) and Great Wall (China) on top of more than 200 marathons in his native US.
On Sunday, the prolific runner from Fishers, Indiana, plans to complete his Pan-Continental running odyssey in Auckland.
Currently on a trip to New Zealand that takes in a glacier walk and a tandem parachute jump with his wife, Mr Smith is fully embracing his adventure to this part of the world.