On the night of March 5th and 6th, 2021, a freight train traveling from Robeston oil terminal to Theale oil terminal suffered severe wheel flats on one of its wheelsets, causing the wagon to fracture two rails within a mile of each other between Pencoed and Llanharan. An investigation found that the wheelset had locked during braking on the recently reopened Swansea District line, which had rusty rails and very low railhead adhesion due to moisture.
The report by the Rail Accident Investigation Branch (RAIB) found that Network Rail had not taken any specific precautions to ensure an adequate level of adhesion was available when reopening the line, as their focus was on managing low adhesion during the autumnal leaf fall season. As a result, RAIB has recommended that Network Rail reviews its processes to manage all occasions outside of the leaf fall season that could result in very low levels of wheel/rail adhesion.
Additionally, the investigation has identified a learning point for signallers to remember that they must arrange for a train to be stopped and examined if they become aware of an unusual noise coming from a wagon, in accordance with the Rule Book.
The report also notes that the findings may be relevant to the Ferryside accident in 2018 and an addendum has been added to that report to discuss the potential causal factor of very low adhesion.
The report highlights the importance of taking necessary precautions when reopening unused railway lines to ensure adequate levels of adhesion and the need for continued attention to safety measures even outside of the leaf fall season.
Source: Gov[Dot]UK
