Forty years on, it remains the worst train crash in Australian history.
On January 18, 1977, locomotive No. 4620 derailed and struck the Bold Street bridge near Granville station in Sydney's west, shortly after 8am.
The 170-tonne concrete bridge collapsed on the packed commuter train, which was travelling to Sydney from Mount Victoria in the Blue Mountains, crushing the third and fourth carriages.
Eighty three people were killed and more than 200 others were injured.
Gerard Buchtmann, who was chief of the Nepean Volunteer Rescue Squad, said he arrived on the scene at 10.25am to "absolute devastation".
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"None of us had experienced anything like this," said Mr Buchtmann, who was 31 years old at the time.
He said rescuers removed bodies and train seats to get to survivors.
"One particular lady, she was face down on the floor with the roof on top of her, and she was there from the time of the incident until we got her out about half past 3," he said.
"She only died last year, and I actually went to her funeral."
On Wednesday, Mr Buchtmann will join survivors, victims' families and rescuers at a service remembering the 40th anniversary of the disaster.
In the years since the crash, he said he had only missed one anniversary service.
Attendees will first gather opposite the rebuilt Bold Street bridge, at a commemorative memorial unveiled in 1997 to mark the tragedy and the heroism of rescuers.
Transport Minister Andrew Constance also confirmed this week that the NSW government will issue a formal apology to those affected when parliament resumes next month.
"Obviously, everyone's deeply sorry for what has occurred," Mr Constance told the ABC.
Investigations into the crash revealed ageing infrastructure and a lack of investment in maintenance.
Then-premier Neville Wran described the state of the railway system as "ramshackle", and following the disaster, the state government borrowed heavily to modernise the railway.
