It was the horrific head-on rail crash in which four people died which led to safety improvements across the country.
Two drivers and two passengers died and more than 30 were hurt in a crash on a stretch of single track at Newton.
Today (Wednesday) 30 years on, a service of commemoration and a minute's silence to mark the anniversary of those how lost their lives in the horrific crash.
The short service at Newton train station will be led by the railway chaplain Graham Whitehead.
And Stuart Scott, the brother of 27-year-old driver David Scott, who was killed in the crash is to pay his own tribute.
Wreaths will be laid at the station, in memory of the victims, by ScotRail Operations director David Simpson and ASLEF’s Scottish organiser, Kevin Lindsay.
Staff at ScotRail, and members of ASLEF, the train drivers’ union, are also expected to pay their respects.
The four dead were train drivers Mr Scott, Reginald McEwan, 61, and passengers Mr Kenneth Meechan, 20, and Tracey Donnachie, 18.
Kevin Lindsay, ASLEF’s organiser in Scotland, said: "It is with great sadness that we remember the events of 21 July 1991, when two commuter trains crashed just west of Newton railway station at Cambuslang near Glasgow.
"The railway family in Scotland will come together to observe one minute’s silence to remember those who died and those who were injured. It is vitally important that we work, every day, to improve the safety of our railway and do nothing to compromise the safety of passengers and staff."
It was at 9.55pm that the Newton to Glasgow Central Cathcart Circle service, a British Rail Class 303 unit driven by Mr McEwan, left the ‘down’ platform at Newton.
Meanwhile, the 8.55pm Balloch to Motherwell service, a Class 314 unit driven by David Scott, was crossing from the fast West Coast main line tracks through a single-lead junction to enter the ‘up’ platform.
Tragically, the two trains collided head-on at the junction. The impact speed was about 60mph.
The Class 303 overrode the buffer unit of the Class 314 and the trains telescoped over one another.
The leading coach of the 314 was completely destroyed.
People who lived in the area near to the crash described hearing something that sounded "like an explosion" and soon 400 people had gathered at the crash site.
One local ran to Newton to telephone the signaller on duty and had asked him to turn the overhead wires off as he had feared for the safety of everyone.
Mick Whelan, general secretary of ASLEF, the train drivers’ union, said: "We will never forget the two drivers, and two passengers, who died in the crash at Newton. We must ensure that we never forget the lessons from this tragedy, to ensure that we keep the people who work on, and travel on, our railway safe."
The junction had been remodelled from being double track just a month before the crash. The junction's configuration was installed at a cost of £5 million and designed to be simpler than the 'double-lead' junction that it replaced.
A Health and Safety Executive report said that if risk assessment techniques had been used by British Rail when the track was being remodelled a month before the accident, it was likely that the accident risk could have been foreseen.
David Eves, HSE deputy director-general, said one of his main recommendations was that railway operators should now develop, in consultation with the HSE, risk assessment techniques for proposed schemes involving single-track working.
An HSE report said that after the Newton accident, British Rail carried out a risk assessment of similar single-lead junctions, where, in an area with two or more tracks, only a single crossover exists. This immediately identified 10 locations, including Newton, where extra protection measures were judged necessary.
At the time of the Newton accident, some trains were running late - one significant factor among many that contributed to the circumstances of the accident, it says.
But the introduction of single-lead junction which replace parallel double tracks at Newton was a major contributory factor. The inquiry report recommended that double lines should be reinstated there, as ScotRail told the inquiry it intended to do.
The HSE inquiry found that 'on the balance of probabilities', the platform starting signal was at red when the Glasgow-bound train pulled out and that for the other train, the signal was clear.
But it said that in the circumstances it was impossible to expect a signalman to recognise indications of "impending catastrophe" on his panels and to alert both drivers.
The integrity of the signalling system at Newton was not in doubt, although "serious questions" arose as to its local reliability and manner of installation, the inquiry report continued.
The fact that three "very serious accidents" had occurred in the recent past at similar junctions could not be ignored.
The HSE questioned the total reliance that British Rail had placed in some higher-risk situations on drivers' behaviour in observing signals when there is a substantial body of evidence of the number of signals passed at danger each year.'
Following the accident the junction was closed, with a special timetable in place for several months while the layout was revised to provide double track from the platforms towards Kirkhill.
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