Almost 40 years after Australia's worst train disaster, the New South Wales Government says it will apologise to the "families left with unimaginable grief" as a result of the tragedy.

Andrew Constance said it was "one of the most horrific tragedies in the nation's history". ( AAP: Dan Himbrechts )

In an exclusive interview with ABC News in the lead-up to the 40th anniversary of the Granville train disaster on January 18, Transport Minister Andrew Constance said: "Obviously everyone's deeply sorry for what has occurred."

"Over the years, people have had to cope with what was one of the most horrific tragedies in the nation's history."

Eighty-three people died and another 213 were injured when a commuter train derailed near Granville railway station and a bridge collapsed onto the carriages in 1977.

At the time, then-New South Wales premier, the late Neville Wran, described the state of the railway system as "ramshackle".

Investigations and inquiries revealed an alarming lack of investment in maintenance and ageing infrastructure, and following the disaster, the State Government borrowed heavily to modernise the railway.

At the time, the state of the railway system was described as "ramshackle". ( ABC News )

Government 'turned its back' on families, survivors

Meredith Knight led the call for an apology. ( ABC News: Philippa McDonald )

Meredith Knight's father Bryan was among those on the packed commuter train that day, travelling from the Blue Mountains.

"He was in carriage three. There were only three people who were still alive," Ms Knight said.

"They got my father out within an hour and half, onto a helicopter and to Royal Prince Alfred Hospital.

"He survived three days and he never regained consciousness."

At 15, Ms Knight had to leave school and get a job to help support the family.

"We were basically just ignored," she said.

"That was the case with all the families and the survivors — the Government turned its back on us, it swept it under the carpet.

"They didn't want to know about us."

Meredith Knight's father was among those killed in the Granville train disaster. ( Supplied )

Ms Knight, who led the call for an apology, said: "I feel elated, finally it's a recognition of what we went through."

Ms Knight and other families told ABC News they would pay close attention to the wording of the apology.

"Hopefully, when that apology is given in Parliament, it is sincere and genuine with a real compassion," she said.

"It might be 40 years, but a lot of people are still suffering."

'Thank goodness, at last'

Wendy Miles lost her two daughters, 11-year-old Helen and eight-year-old Rosie, along with her father Walter and stepmother Madge, in the disaster.

Wendy Miles described the Granville disaster as "a neglected tragedy in a lot of ways". ( ABC News: David Hudspeth )

Ms Miles said an apology "means not just myself but a lot of people are going to get some comfort from it and, in a lot of cases, a reduction in anger".

"I heaved a sigh of relief and thought: 'Thank goodness, at last'," she said.

"It's taken 40 years — 40 years is a long time for someone to say what they need to say."

The New South Wales Government paid for the funerals of her loved ones and she received $1,000 for each of her daughters and $500 each for her father and stepmother.

Wendy Miles lost her two daughters, 11-year-old Helen and eight-year-old Rosie, in the disaster. ( ABC News: David Hudspeth )

Ms Miles described the Granville disaster as "a neglected tragedy in a lot of ways".

"Once it was over, it received little attention," she said.

Andrew Constance said it was a tragedy "which no-one would ever get over". ( AAP: Dean Lewins )

"The word 'apologise' would have to come into [the Transport Minister's statement] in order for it to be an apology.

"And I'm sorry, I'm not one of those people who will say he more or less apologised — that just won't work.

"The actual word has to be used for it to be an apology."

Mr Constance said he had met with people "directly affected by what happened on that day".

"I think it's important that, with a commemoration such as the 40th anniversary coming up, that the Parliament also recognise the life-long effect, the unimaginable grief that people have been left with as a result of Australia's worst train accident," he said.

"It's a tragedy which no-one would ever get over and it's hard for a lot of us to imagine the grief that people experience life-long because of the very nature of that happened."