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Botched drainage construction undertaken by Carillion has been blamed for the Stonehaven derailment which killed three people in August 2020.
According to the Rail Accident Investigation Branch's (RAIB) report into the derailment, released today, the trench containing a perforated pipe, constructed by Carillion between 2011 and 2012, was at the centre of the enquiry. The pipe was installed as part of a project to address a known problem with drainage and cutting stability at the site.
However, the drainage system and associated earthworks had not been constructed in accordance with the original design and so were not able to safely accommodate the water flows on the morning of the derailment.
The 51.5mm of rain which fell that morning was close to the average rainfall for the whole month of August in this part of Scotland - and the train derailed because it struck debris that had been washed out of the drainage trench.
RAIB investigators found that a low earth bund had been constructed across a slope leading towards the track. The presence of this bund significantly altered the flow of water such that extreme rainfall would cause a concentrated flow into the steeply sloping section of trench. The 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 says: "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.
"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."
Carillion has been in liquidation since January 2018.
According to the report, other differences between the original design and the installed drainage system were probably not causal but do provide evidence of "an absence of control of construction changes". These included:
- Omission of the intended connection from the existing (pre-2010) drainage into the 2011/12 drain at catchpit number 18
- Relocating catchpit 18
- The lack of geotextile lining to the trench (required to prevent fine soil particles entering the drain and clogging it up) in the area of the washout
- Cutting holes in the side of catchpits on site so that the holes were significantly larger than the pipes passing through them
- A bend in the pipe not coinciding with a catchpit (about 1m downslope of catchpit 18)
RAIB found no evidence that any of these changes were referred to the designer, Arup, for consideration - but it says they should have been.
It says that while the contractual arrangements between Network Rail and Carillion meant that Carillion was "responsible for the delivery of works in accordance with designs approved by Network Rail, together with amendments agreed through formal processes" there is "no evidence" that changes were dealt with as part of a formal process. This would have included referring them to Arup.
The report adds: "Network Rail’s project team were probably unaware that the 2011/12 drain was significantly different from that intended by the designer and therefore did not take action. Had they been aware of this, it is possible that the consequent risk would have been recognised and remedial actions taken.
"Although Network Rail had a project team, they were not required by Network Rail business processes to check that the drain was being installed in accordance with the design. They therefore relied on a contractual assurance process that required Carillion to refer proposed changes to the designer, Arup, for approval."
RAIB chief inspector Simon French said the investigation "highlights the risk of uncontrolled changes to railway infrastructure during construction".
He added: "It is so sad that a project that was designed for the protection of the travelling public became unsuitable for its intended use and posed a hazard to trains because of such uncontrolled changes to the design. When anything is built in difficult conditions, such as on the side of a steeply sloped cutting, changes will often be needed for practical reasons.
"Although such changes are normal and can be highly beneficial in terms of saved time and cost, they need to be made with care. In each case, the original designer needs to understand the change that’s proposed and review the implications of a change that may appear inconsequential to the team on site. I hope this example will resonate throughout the UK’s construction industry."
Recommendations
As a consequence of this accident, RAIB has made 20 recommendations for the improvement of railway safety. The areas covered 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
- Improved operational response to extreme rainfall events, exploiting the full capability of modern technology, and based on a detailed understanding of the risk associated with extreme rainfall
- Enhancing the capability of route control offices to effectively manage complex events
- Extending Network Rail’s assurance regime to encompass route control offices
- Addressing the obstacles to effective implementation of lessons learnt from the investigation of accidents and incidents
- Measures to prevent derailed trains from deviating too far from the track (equipment fitted to track and/or trains)
- Addressing train design issues identified by the investigation and better understanding the additional risk associated with the operation of older trains
Overall, French described the derailment as “a reminder of just how disruptive and potentially dangerous Britain’s volatile weather can be".
"The railway industry needs to get even smarter about the way it counters this threat, and to better exploit remarkable modern technology that enables the prediction and tracking of extreme weather events such as summer convective storms," he said. "There’s also an urgent need for the railway to provide real-time decision-makers with the information, procedures and training they need to manage complex and widespread weather-related events across the rail network."
Network Rail chief executive Andrew Haines said that the 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," he said. "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.”
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“”Better management of civil engineering construction activities by Network Rail “”. Where is the response from NetworkRail stating what they’ll do to properly and accountably manage their responsibilities instead of just passing off these to a contractor?
There is never a single point of responsibility for failure with regards to safety issues. There is obviously a responsibility of the Contractor, but what about the Client with regards to knowing and checking construction works, what about line checking after such severe weather. I am sure there are many other points along the timeline since the start of construction works until the accident that this disaster could have and should have been averted. Too easy to blame a single entity, especially when they are no longer in business. Seems like a larger problem here.
Simply embarrassing; as a professional civil engineer, this is an embarrassment. However, would a full root cause analysis not end up looking at, and asking, ‘why does a contractor feel the need to, effectively, cover up changes made to a design and lower the cost to itself?’ Is this an isolated case? Does this just affect civil engineering? Does it still happen? Who will we be looking back at in 10 years time and saying to ourselves, ‘But I always considered them to be a professional outfit’? We can put control measures in place to try to eliminate these instances of neglect/ error/ poor work/ misunderstanding, but why do we have a working environment that doesn’t make this behaviour unacceptable? It is simply the hierarchy of risk management- eliminate the risk ahead of trying to manage it. As engineers, we often talk about ‘safe by design’. Why is our working environment not safe by design? Money. Many in this wider construction sector are not valued by society and this translates to not valuing ourselves. Why else would some be happy to work for near zero margins and then work out how to keep the business afloat later? I do not disagree with the gentleman commenting before me, but a competent contractor should be able to take the responsibility, add value to their offering to the client and be valued for doing so. But the ‘policing’ of a job, the Quality Assurance needs to be beyond reproach.
I read: Overall, French described the derailment as “a reminder of just how disruptive and potentially dangerous Britain’s volatile weather can be”, and “The railway industry needs to get even smarter about the way it counters this threat, and to better exploit remarkable modern technology that enables the prediction and tracking of extreme weather events such as summer convective storms” So, does the Rail Inspector not mention climate change and its possible implications? Is there modern technology that incontrovertibly predicts the extents of climate change to expect, in this instance a month’s rain in half a day? Or are we into intelligent guesses?
Was there independent design assurance and supervision of the works? Clearly not. Probably another scheme where the contractor was self certifying.
Race to the bottom.
“Although Network Rail had a project team, they were not required by Network Rail business processes to check that the drain was being installed in accordance with the design. They therefore relied on a contractual assurance process that required Carillion to refer proposed changes to the designer, Arup, for approval.”
This statement sums up an issue throughout our industry. We used to have Resident Engineer teams independently checking site works. The movement to self certification has not worked. Just created small cost savings during construction and major issues post completion. Construction works should be independently checked and certified.
Agreed 100% – ad that is how it used to be. Also the PWay ganger and his length-men held a proprietorial interest in ‘their length of ‘route’ and soon brought such problems to the attention of the District Inspector, and thence to the District Engineer. These members of the team had a wealth on local knowledge that was invaluable – it really did not need a Resident Engineer to check such works – the local men knew the problems and how they should have been solved.
Perhaps I am being stupid but I would really like to see a diagram to understand exactly how the bund caused the problem. I am not saying there was not one: obviously there was, with tragic consequences, I am just trying to learn for the future. Hopefully more information will be available soon.
Full report here with photos and diagrams. https://www.gov.uk/raib-reports/report-02-slash-2022-derailment-of-a-passenger-train-at-carmont
Bring back the RE
Absolutely agree, and the civil engineering inspectors and clerks of works. And on a not unrelated theme, absence of the latter, looking after the interests of the prospective purchasers and not the builders, explains the numerous reports of shoddy workmanship on our new housing stock.
I am in complete agreement with those pointing out the obvious need in our industry for the re-introduction of the RE and the CoW. Having worked in construction for 45 years as (inter-alia) Contractor, RE, CQA Engineer and designer for unsupervised D&B schemes it is clear that the forces at work in an unsupervised price competitive construction environment works against the delivery of quality and increases the risk that what is built is not as it should be. It is a naïve person that would imagine otherwise. Any intelligent Client who has a basic understanding of human nature and the construction industry ought to run a mile from unsupervised infrastructure delivery.
Here, here, — so what will be the role of the Chartered Infrastructure Enfineer in such cases. Where will be the on-site, dirty booys, input ? ?
Excellent observations regarding those rather archaic values of lifelong career ownership, commitment, interest and experience, which can only be measured at sad times like this.
There used to be Quality, which was superseded by Quality Control, which was in turn superseded by Quality Assurance, then because QSs make the world go round and a lower headcount means less obvious cost, the industry now relies on QS threats to sue contractors who are deemed after the event to have failed to meet their quality, or any other contractual, obligations.
Unfortunately, unlike the Carillion Southmead Hospital example, that modern approach doesn’t even offer the intended contractual pyrrhic victory in this tragic case.
It also illustrates that safety is not a separate growth industry, again heavily populated by QSs. If the Chartered Engineer is allowed the necessary resources and as a result achieves the required quality, then the obvious safety requirements are also achieved.
Thank you to IRH for the link to the official report. Now I understand. The bund ran across the side of a field, channeling water to the single point of the new drain, so creating really concentrated flow and making washing-out of the new drain even more likely. I wonder why someone thought the bund was a good idea?