Llanelli - Carmarthen broken rail

[GB]

Don't quite follow but this train has been running almost on a daily basis for many years now without serious incidents

Things can change over time. The North Walsham - Harwich tanks ran as RA10 for years but only recently has not been allowed to run over RA8.

 

[2HAP]

RAIB investigation opened.

https://www.gov.uk/government/news/extensive-track-damage-between-ferryside-and-llangennech

 

[Chris M]

The RAIB’s preliminary examination has concluded that the brakes of all the wagons in the train were almost certainly properly released when the train left Robeston. It appears at present that one set of wheels ceased to rotate at some point during the journey, leading to the development of the wheel flats, and began to turn again in the Ferryside area. The impacts from the rotating, damaged, wheels gave rise to the broken rails, and may also have caused the disintegration of the brake rigging.

Our investigation will try to determine the sequence of events and find out why the wheels behaved in this way, and why the braking components failed.

(extract from the link in @2HAP's post)
This sounds like it could be quite a complex investigation, and brings to mind one from several years ago where a passenger train wheel cracked (disintegrated?) - I think it was a Class 222 (possibly Midland Mainline), but I haven't got time to look right now. In that case ISTR they had to build a full-size testing rig to get to the bottom of the problem and the final report was released nearing two years after the incident.

Edit: I was thinking of the East Langton derailment of an East Midlands Class 222 in February 2010. The RAIB report was published in January 2012.

On 20 February 2010, at around 15:49 hrs, a seven-car Meridian diesel multiple unit
passenger train derailed by one axle of the fourth vehicle, while travelling on the
Midland Main Line near East Langton. The train was travelling at a speed of 94 mph
(151 km/h) when the derailment occurred, and it subsequently ran for a distance of
approximately 2 miles (3.2 km) before it stopped. […]
The immediate cause of the derailment was the complete fracture of the powered
trailing axle of the leading bogie on the fourth vehicle.