The Aslef train drivers’ union said its concerns about the High Speed Train (HST) rolling stock were not acted on.
On Thursday, a detailed report into the August 2020 crash was released by the Rail Accident Investigation Branch (RAIB).
While the crash was caused by the train hitting gravel which had been washed onto the track, the report found the train involved was designed before modern safety standards were introduced.
It said the outcome would likely have been better if the train had met crashworthiness standards introduced in 1994.
It was reported that Aslef’s general secretary wrote to the Office of Rail and Road’s (ORR) chief inspector Ian Prosser with concerns about the ageing HST fleet.
The letter said: “At least one report produced a number of years ago assumed that the fleet would be replaced by now, and also questioned the safety of the driver if involved in a high-speed collision.
“Aslef therefore wants to see an up-to-date report on the crashworthiness of HST power cars before we agree to their operation past 2020.”
Kevin Lindsay of Aslef said: “There was an opportunity to intervene and we were given the brush-off.
“Chief Inspector Prosser basically said the trains meet the standards and, as such, there is no issue to investigate.
“Hindsight is a wonderful science but maybe he should be looking at himself and saying: ‘Maybe we got that wrong.’
“Just because something met the safety standards when it came in doesn’t necessarily mean it should still be allowed to run 40 years later.”
Following the RAIB report on Thursday, Scotland’s Transport Minister Jenny Gilruth announced a steering group was being set up to examine the safety of older trains on Scotland’s railways, including the HST fleet.
Three people, including the train’s driver and conductor, died in the accident near to Carmont signal box in August 2020.
Responding to Aslef’s comments on the 2018 letter, an ORR spokesman said: “Our thoughts remain with the families of Christopher Stuchbury, Donald Dinnie and Brett McCullough and we welcome the Rail Accident Investigation Branch report and detailed recommendations that need to be addressed with urgency.
“As the safety authority, ORR will be working rapidly with all the parties that the RAIB recommendations are directed at, to review their initial response, and lead in setting out a clear plan for how the recommendations will be addressed and action taken.
“The specific RAIB recommendations on High Speed Trains affect many parties and so we will be bringing all these organisations together as soon as possible to start a review to identify if there are reasonably practicable improvements that can be made regarding High Speed Trains.
“It is a strength of our rail system that safety standards improve over time to ensure our railway remains one of the safest in Europe.
“The arrival of a higher standard does not render earlier designs unacceptable and in 2018 we had no evidence to suggest that the High Speed Train should be subject to any review of its crashworthiness.”