A fatal train collision near Talerddig, Powys, on 21 October 2024 has been the subject of a Rail Accident Investigation Branch (RAIB) investigation. The collision occurred between two passenger trains operated by Transport for Wales Rail Limited (TfWRL), which were travelling on Network Rail's Cambrian lines. The RAIB report reveals that the accident was caused by train 1J25 passing its authorised stopping position and entering the single line beyond, where it collided with train 1S71.
According to the report, low wheel-rail adhesion and a steep downhill gradient contributed to the accident. The train's sanding systems, which could have mitigated the low adhesion conditions, did not function properly. The RAIB investigation also found that there were no engineered mitigations to prevent train 1J25 entering the occupied single line in the event of an overrun.
The collision resulted in one fatality and multiple injuries, with 23 people requiring medical attention. The railway remained closed until 28 October 2024 while repairs were carried out. The RAIB has made nine recommendations to improve safety, including improvements to trainborne sanding equipment and overrun protection.