The accident occurred on 12 August 2020 when a train struck debris which had been washed onto the line during exceptionally heavy rainfall, resulting in the deaths of train driver Brett McCullough, conductor Donald Dinnie and passenger Christopher Stuchbury.
In her determination, Sheriff Lesley Johnston identified precautions which might realistically have prevented the derailment, including ensuring that the drainage system was constructed in accordance with its approved design and that accurate construction records were obtained by Network Rail.
The sheriff also found that failures in the construction and documentation of the drainage system contributed to the derailment.
The Fatal Accident Inquiry followed the prosecution and conviction of Network Rail Infrastructure Limited for a breach of health and safety legislation arising from the derailment.
The sheriff concluded that extensive work undertaken by Network Rail and the wider rail industry since the accident had addressed the safety issues identified during the inquiry.
Following publication of the determination, Laura Buchan, Legal Director with the Crown Office and Procurator Fiscal Service (COPFS), Scotland's independent deaths investigation authority, said:
"Our thoughts remain with the families, friends and colleagues of Christopher Stuchbury, Donald Dinnie and Brett McCullough and everyone affected by this tragedy.
"Fatal Accident Inquiries play an important role in ensuring deaths which give rise to significant public concern are examined fully, independently and in public. They can help families understand what happened, identify opportunities to improve safety and prevent future deaths.
"This inquiry provided a detailed public examination of the circumstances that led to the derailment and the factors that contributed to it.
"The sheriff found that important changes have been made across the rail industry since the derailment and concluded that these measures have addressed the safety issues identified during the inquiry."
Further information
For more information on Fatal Accident Inquiries, see the Crown’s guide.