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expert reaction to train derailment near Stonehaven

A passenger train has derailed in Aberdeenshire, resulting in the deaths of at least three people. 

 

Prof Roderick Smith FREng, a Fellow of the Royal Academy of Engineering, and Future Rail Research Centre, Imperial College London, said:

“I have just seen photographs of the crash site taken from the air.  The destruction of the robust rolling stock is shocking.  It very much looks like a high speed derailment and the damage is much greater than what would occur had the train been proceeding slowly.  The fact that the driver was killed may also indicate that if the train ran into an obstruction on the line then it did so at a considerable speed.”

 

Prof Roger Kemp MBE FREng, Fellow of the Royal Academy of Engineering and Professorial Emeritus at Lancaster University, said:

“At the time of writing (Wednesday 15:00), there is little information to go on.  Between Aberdeen and Stonehaven, the line runs near the coast but, south of Stonehaven, it turns inland along a deep and wooded river valley, which is where the derailment occurred.  With reports of recent heavy storms in this area, a landslip or mudslide seems a likely cause.

“The HST, which has been a workhorse of non-electrified routes for 40 years, is known as a solid, reliable type of train with a good safety record.  Having a heavy power car at each end means passengers are well protected from obstructions on the track.

“All rail passenger coaches are built to withstand much higher forces in accidents than are road vehicles.  When a West Coast Pendolino train rolled down an embankment, after a 95 mph derailment in February 2007 caused by a faulty set of points, all the coaches remained structurally intact.  Although standards have been upgraded since the British Rail Mk 3 coaches used in the HST were built, they are still robust and have been proved in service to survive accident damage.

“Although one cannot blame a specific storm or flash flood directly on global warming, the increasing temperature means air can hold more water vapour, so storms and floods are likely to be more intense than in the past.  Much of the UK’s railway infrastructure was constructed in Victorian times, since when the likelihood of extreme storms has greatly increased.  Network Rail is well aware of the increased risk posed by climate change.  They, and the authorities responsible for the road infrastructure and flood management, have a challenging time ahead trying to predict and pre-empt the effects of global warming.”

 

Prof Bob Hutchison, Honorary Professor in Railway Systems, UCL, said:

“For me there isn’t enough information at this time to make a judgement but I can give you my personal observations.  I am not a rail incident/accident specialist but have been in railway engineering and consultancy for 50 years and I am currently an Honorary Professor (Railway Systems) within CEGE (UCL Civil, Environmental & Geomatic Engineering).

Is there enough information available yet to be able to know what happened?

“No but one can speculate.  You need the initial site investigation reports/announcements to make a technical response.

What will be being done at the scene to establish what happened?

“From my experience, the site will probably be treated very much like a ‘crime scene’ by British Transport Police and controlled by emergency services with evidence being collected by investigators.  However the immediate priority will be making the site safe and dealing with the injured and non-injured and preserving of evidence.  In the background experts and other railway officers will be checking the scene probably under supervision of scene managers.  Office of Road and Rail (ORR), Rail Accident Investigation Branch (RAIB) or Scottish equivalent will be involved, along with train operator and Network Rail.  Rolling Stock records (on train), track inspection records and civil earth structures and infrastructure records and any fault records will be examined plus operational control/signalling reports and initial incident reporting and management.  This evidence will be preserved.

Is weather and landslips a possible cause of derailment in general?

“Without knowing the asset history of that section of the route nor its infrastructure configuration nor the earthworks (embankments or cuttings) then I cannot really comment.  However, there have been several earth slips within the UK which have not been helped by poor weather that has destabilised the earth structures.  But again this is speculation at the moment as track condition and geometry needs to be verified.  Also any third party non-railway causes need to eliminated e.g. deliberate or accidental.

Are railways built to be able to withstand a certain degree of severe weather?

“Generally yes but there will always be exceptional weather conditions coupled with asset conditions.  Cannot comment specifically in this case.  Network Rail and rolling stock designers and operators have strict standards in place.

Are trains built to cope with possible derailments?

“Yes, dealt with in the current standards and train specifications parameters.  Vehicle integrity and crash worthiness is specified, as too the built infrastructure.

Any other comments?

“From pictures it appears one of the train’s non passenger carrying driving power cars is a Class 43 High Speed Train (HST) unit numbered 43030. Depot is Haymarket.  Train is probably TWO x class 43 power cars, one at each end and possibly 4 to 5 Monocoque type Mark 3 coaches.  Each power car has a diesel engine driven generator unit of about 2000hp (about 1600kW).  Power car fitted with diesel fuel tanks (reference Traction Recognition Book just over 1000 gals when maximum filled – unlikely in this case).  HSTs were introduced by BR from 1976 – 82 so they are older vehicles on the network but still with a good safety record and still giving good reliable service.  The unit in picture was transferred to Scot-rail in Feb 2018 (source on line Scot-rail Fleet list).”

 

Prof Roderick Smith FREng, a Fellow of the Royal Academy of Engineering, and Future Rail Research Centre, Imperial College London, said:

“I comment with some cautions as details are so sparse.

Is there enough information available yet to be able to know what happened?

“Emphatically no. I have read that three carriages have fallen (rolled?) down an embankment.  As well as a land slip being involved, the video of water flooding the track suggests that ballast may have been washed away leaving the rails unsupported.  It may be we are dealing with a collapse of the track as well and/or causing the derailment.

What will be being done at the scene to establish what happened?

“Obviously the priority is dealing with casualties, then a thorough investigation will begin to establish the cause.

Is weather and landslips a possible cause of derailment in general?

“Yes:

Flooding, washing out of track support.

Landslip, obstructing the track with the possibility of derailing a train.

Sunshine, track bucking.

Cold temperatures, fracture of the rails.

Are railways built to be able to withstand a certain degree of severe weather?

“Yes.

Are trains built to cope with possible derailments?

“Yes.

“But in both cases there is a limit on what is physically possible.  It looks as though the train involved as an HST, possibly the most successful UK train ever built.  Even in a severe derailment it is unlikely that the carriages will be badly damaged, but the passengers inside could be tossed about significantly, possibly leading to serious injury, the severity depending on the exact detail of how the train moved down the embankment if indeed this is the case.

Any other comments?

“It really is unwise and unhelpful to speculate too much until more details are released.  It is perhaps surprising that so long after the accident happened, more details have not been released.”

 

Prof William Powrie, Professor of Geotechnical Engineering, University of Southampton, and Convenor of the UK Collaboratorium for Research in Infrastructure and Cities (UKCRIC), said:

Is weather and landslips a possible cause of derailment in general?

“A landslip that either moved the track or deposited a large volume of earth onto the track (e.g. a landslip into a cutting) could derail a train; in the first case because the track was no longer in the right place or had become distorted so much that the train could no longer remain on it, and in the second case because the earth represented an essentially immovable obstruction.

“Stable ground can become unstable if the pressure of the water in the soil pores rises too much – rather like a sandcastle, which can be built with near vertical sides in damp sand (where the water is actually in suction and helps hold the sand grains together) but collapses into a heap with a much shallower slope angle when it becomes properly wet.  Pore water pressures are influenced by rainfall and vegetation – it is quite possible for pore pressure increases to make a slope such as an embankment or a cutting become unstable after heavy rainfall.  (Vegetation usually helps in the summer, because evapotranspiration removes water from the ground tending to keep the pore water pressures low).  It is also possible for water acting directly on an embankment to cause it to fail, for example if there has been a flood and water has built up on one side only of an embankment.  I don’t know yet from the news reports what the mechanism was in this case, but heavy rainfall and water acting directly can both cause slope failure or a ‘landslip’.  And a landslip can derail a train.

Are railways built to be able to withstand a certain degree of severe weather?

“Yes – they need to be able to withstand a degree of variation in soil conditions and pore pressures; and also many decades of cycling between the usual extremes of summer and winter.  However, climate change is leading to more frequent extreme weather events – such that, for example, what is currently a one in 50 year weather event will become a one in 5 year weather event in the future.  And we also see the juxtaposition of extremes, all of which puts more stress on our infrastructure.  This is a major challenge of adapting to the impacts of climate change – dealing with more frequent extreme events.”

 

Prof Anson Jack, Professor of International Railway Benchmarking, and International Director of the Birmingham Centre for Rail Research and Education, University of Birmingham, said:

Is there enough information available yet to be able to know what happened?

“No – there is really only speculation at present – indications are that the incident is related to the appalling weather and rainfall in the previous 24 hours, possibly leading to landslips.

What will be being done at the scene to establish what happened?

“First activity is always to secure the site to avoid any further harm to people – what is needed will be determined by the conditions, but getting any passengers and crew out and away from the train will be the first priority.  It appears there may be a fire, so emergency services will need to get that under control.  Only when the site is secured for people and further damage will investigators start to look at the possible causes.  If the cause was a landslip, that will become known fairly soon I would expect.

Is weather and landslips a possible cause of derailment in general?

“Yes, it is one of the known risks that may cause derailments.  Although there have been cases of landslips causing derailments, there have been no fatalities in any form of train accident for over 13 years (Source RSSB and ORR).

Are railways built to be able to withstand a certain degree of severe weather?

“Yes, railways are very resilient against the weather and are often able to run in fog or snow when planes and cars are not able to.  As in the previous comment, there are very occasional bankslips which can cause derailments, but Network Rail is progressively investing in more robust infrastructure, and there have been no incidents leading to loss of live for several decades.

Are trains built to cope with possible derailments?

“Yes, trains are designed to minimise harm in the very rare event of derailment – modern train design includes things like bogie (wheel assembly) retention, buffer override protection, crumple zones at the end of coaches, smooth rounded surfaces on interior finishes, windows made of laminated glass (to stop passengers being ejected during accidents) etc.  It appears from some of the photos in media reports and social media that the train involved was a recently converted High Speed Train – these trains have been the backbone of the intercity rail network for the last 40 years and have been upgraded in that time.  These trains have been extremely reliable and safe during this time and the previous rare incidents have not been a consequence of the train itself but of other factors.

Any other comments?

“Trains are by far the safest form of land transport, and the industry and its regulator use the experience of all operations feedback, together with the results of inquiries into the rare accidents that do occur to adjust operations and engineering practices and designs.  The UK railway is acknowledged to be the safest major railway in Europe, but efforts continue to improve safety still further, and Network Rail’s investment in embankments is an example.”

 

Prof Hannah Cloke, a hydrologist at the University of Reading, said:

“It is still too early to know what caused this terrible train crash, but the very heavy rain that fell overnight in that part of Scotland was certainly heavy enough to cause significant problems to railway infrastructure and destabilise slopes.  The sudden, extreme rainfall we are experiencing in parts of the UK at the moment can affect almost any part of the country, even areas which are not used to floods.  Flood water cascading down a steep slope can easily have enough force to wash away railway lines or hard engineering features that support them.  My thoughts are with everyone involved in this tragedy.”

 

 

Declared interests

Prof Roger Kemp: “I’ve recently retired and, for the previous 17 years worked at Lancaster University with no funding from the rail industry.  Prior to that, I was UK Technical & Safety Director of Alstom, so could be said to have a reputational interest in the Pendolino trains.  I never worked on the HST.”

Prof Anson Jack: “No conflicts.”

Prof William Powrie: “Some of my research is funded by Network Rail and we have a framework research contract with them – and investigating the effects of weather, climate and vegetation on (especially old) earthworks is a major research area for us (and of interest for Network Rail).”

None others received.

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