A report into the fatal passenger train derailment near Stonehaven has found that Carillion did not undertake construction of a drain in accordance with the designer’s requirements.
Three people died as a result of the accident on 12 August 2020. ‘Near continuous’ heavy rain had fallen on the site between 06:00 hrs and 09:00 hrs. The 51.5mm of rain which fell in this period was close to the average rainfall for the month of August in that part of Scotland.
The investigation into the crash, undertaken by the Rail Accident Investigation Branch, ruled that the train derailed because it struck debris that had been washed out of a drainage trench. The trench, constructed between 2011 and 2021, had not been built in accordance with Network Rail’s approved designs, meaning it wasn’t able to safely accommodate the water flows that morning.
The report read, “The company that was contracted to construct the drain, Carillion, did not undertake construction in accordance with the designer’s requirements. Consequently, the drainage system was unable to perform as the designer had intended when it was exposed to particularly heavy rainfall on 12 August 2020.”
Furthermore, RAIB investigators found that a low earth bank (bund) had been constructed that ran across a slope leading towards the track. RAIB said the presence of this bund ‘significantly’ altered the flow water to such an extent that the extreme rainfall would cause a concentrated flow into the steeply sloping section of the trench. Evidence indicates that the intensity and duration of this rainfall would have generated water flows into the trench that were sufficient to wash away the gravel fill and the ground immediately surrounding the trench.
The report continues: “The most significant difference between the original design of the drainage system and the final installation was the construction of a bund running across the slope towards the railway and perpendicular to the 2011/12 drain. This bund, which was constructed outside Network Rail’s land, had the effect of diverting a large amount of water into a gully so that it all reached the drain at the same location, thereby increasing the propensity for washout of the gravel infill. RAIB found no evidence that the construction of the bund was notified to Network Rail or the designer.”
A series of recommendations for an improvement of rail safety include better management of civil engineering construction activities by Network Rail and its contractors; additional standards and guidance on the safe design of drainage systems; and improved operational response to extreme rainfall events which would ‘exploit’ the full capability of modern technology.
Commenting on the publication of the report, Andrew Haines, Network Rail chief executive, said, “This report makes clear that there are fundamental lessons to be learnt by Network Rail and the wider industry. As well as expressing our deep sorrow and regret at the loss of the lives of Christopher Stuchbury, Donald Dinnie and Brett McCullough, it’s important that we acknowledge it should not have taken this tragic accident to highlight those lessons. We must do better and we are utterly committed to that.
“In the 18 months since the accident, we have inspected similar locations and drainage systems across the length and breadth of the country and the added insight the RAIB has provided today will help us in our efforts. We also commissioned two independent taskforces led by world class experts to help us better understand extreme rainfall events and how to better manage our cuttings, embankments and their drainage systems.
“We have invested tens of millions towards improving the general resilience of our railway and how we predict and respond to such events. But this remains a multi-generational challenge and there is still much to do.”