A report into the cause of a major rail incident which saw homes evacuated and 446,000 litres of fuel spilling onto tracks has found defects to the braking system on one of the wagons contributed to the accident.
On August 26, 2020, a major incident was declared in Llangennech, Carmarthenshire when a train carrying 25 wagons derailed, which onlookers said resembled a scene "almost like armageddon".
A large fire broke out in at least three of the wagons as a result of the crash and a number of homes near the railway were evacuated as a precaution. Two employees aboard the train escaped unscathed.
Read more: Rail track reopens more than six months after 'armageddon-like' scenes
The spilled fuel caused major damage to the environment in an area which is both a site of special scientific interest (SSSI) and a special area of conservation (SAC) including cockle beds, natural tidal mud flats, and wetlands.
A report into the incident released by the Rail Accident Investigation Branch (RAIB) on Thursday has revealed why the train derailed and made recommendations to prevent similar accidents happening in the future.
The report found that 10 wagons (positioned third to 12th in the train) had derailed and that around 446,000 litres of fuel had escaped.
The derailment occurred because one set of wheels on the third wagon in the train stopped rotating during the journey. The wheelset had become locked – probably because of a defect in the braking system on the third wagon arising from deficiencies in the design and maintenance of components. The sliding of the locked wheel along the railhead caused damage to the profile of the wheel treads, the report said.
This meant that the wheels were unable to safely negotiate Morlais Junction, near Llangennech, damaging the pointwork and causing the third wagon to become derailed. The following wagons derailed on the damaged track. Some of the derailed tank wagons were ruptured in the accident and the spilling fuel ignited.
RAIB has made nine recommendations as a result of the incident. These cover a review of the actions taken by the owner of the wagons following this and previous accidents and improvements to the maintenance processes at the locations where the wagons involved in the accident are maintained and overhauled.
The probable failure mode of the braking system and the lessons learned from reconstruction tests have led to a recommendation to the manufacturer of some of the braking system components to undertake a review of their design.
A recommendation has been made to the organisations who carry out surveillance and certification of entities in charge of maintenance of rail freight vehicles to review their processes.
A further two recommendations have been made to improve the management of wagon maintenance and to review the technology and systems used to alert train crew, signallers, and railway control offices to wagon defects that may lead to derailment.
The final recommendation is for a review of the arrangements for regulatory oversight of entities in charge of maintenance and certification bodies that are not based in the UK.
Simon French, chief inspector of rail accidents, said: “Trains carrying dangerous goods play an important role in the UK economy but the risks which their operation presents must be adequately controlled. The consequences when things go wrong can be disastrous as we saw at Llangennech in August 2020. Thankfully no-one was hurt but people were evacuated from their homes and the damage, both to the environment and to people’s livelihoods, will take years to put right. The accident also closed the railway line for more than six months whilst the railway was being rebuilt and engineers worked to minimise the damage to the local environment.
“The rail industry’s approach to the safe maintenance of freight wagons needs to improve. In this investigation we found that there were inadequate maintenance practices and a failure to appreciate the importance of the correct fastening of the various components of the tanks wagons’ braking system. This is not the first time that we have investigated an accident where RAIB has identified serious issues with the maintenance of a freight train. Over the last decade we have identified deficient wagon maintenance as a factor in more than 10 investigations including maladjusted suspension, undetected frame twist, and worn bogie pivot liners."
He added: “The majority of our recommendations following our extensive investigation of the derailment at Llangennech relate to improved maintenance processes for freight wagons. The widest-ranging of these urges the freight sector, in conjunction with Network Rail, to develop a comprehensive programme of measures designed to promote the improvement of freight wagon maintenance in the UK. This is intended to be a collaborative effort, which is appropriate given the potential benefits of better information sharing across the sector.
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