A safety system was “blocked” during a fatal train crash in Powys, an initial investigation has found.
The Rail Accident Investigation Branch (RAIB) has published its initial findings into last month’s collision, in which one person died.
David Tudor Evans, 66, was described as a “lovely guy, full of life and enjoyment”.
A further 15 people were taken to hospital for treatment after the crash near Talerddig, police said.
The collision – at around 7.26pm on 21 October – involved the 6.31pm Transport for Wales service from Shrewsbury to Aberystwyth and the 7.09pm Transport for Wales service from Machynlleth to Shrewsbury.
The RAIB said the units were fitted with wheel slide protection systems – described as being similar to anti-lock braking systems in cars – and an automatic sanding system.
Sand is discharged automatically via hoses when a wheel slide is detected during braking – creating more friction at the wheel-rail interface.
A map showing the location of the crash near Llanbrynmair and Talerddig in Powys
The on-train data recorder shows the wheel slide started during braking and was also present after the driver made an emergency brake demand.
An inspection of the sanding system fitted to Aberystwyth-bound train 1J25 showed the leading vehicle’s sanding hoses were blocked.
The RAIB says they were apparently unable to discharge sand.
The ongoing investigation is also looking at the speed at which the trains were travelling when they collided.
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Initial enquiries suggest the westbound train was travelling at a speed of between 15mph and 24mph, while the eastbound train was travelling at a speed of 6mph.
The RAIB says its investigation will look at the sequence of events which led to the crash.
As part of the probe, the agency will look at factors including the actions of those involved, the level of wheel-rail adhesion, and the behaviour of both trains during and after the crash.
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In a joint statement, Transport for Wales and Network Rail said they have “fully cooperated” with the British Transport Police, the Office of Rail and Road and the Rail Accident Investigation Branch.
“As investigations are currently still ongoing, we’ll continue to work together with investigators to understand what happened and await the full conclusion and recommendations of the investigation,” a spokesperson said.
The spokesperson said safety was the “main priority” for both companies and they had “carried out enhanced checks to the trains and the railway line”.
“At this early stage of the investigation, it’s fundamental that we await the findings of the full report and show sensitivity towards our customers, colleagues, the local community and the families of those affected by the incident,” they added.