The Rail Accident Investigation Branch have released a report into the derailment of Citadis 232 at Bulwell on Nottingham Express Transit which occurred at 1706 on 12th June 2023. In the report they set out what caused the tram to be derailed as well as providing recommendations to try and prevent similar incidents from happening in the future.
What happened?
At 1706 on 12th June 2023, 232, was travelling southbound at around 41kmh (25mph) when it approached a set of facing points which were in an unsafe condition at the north end of Bulwell tramstop. As the tram travelled over the points the first and second bogies of the tram were routed in different directions causing the tram to derail.
The tram struck an overhead line equipment support pole which caused a pane of glass to dislodge and strike a passenger which resulted in minor injuries. The driver also suffered a minor injury.
Significant damage was caused to the tram (which has still to return to service) and infrastructure. The line was only able to open again on 23rd June.
Causes
The set of spring loaded points were in an unsafe position as they had not reset correctly after two previous northbound trams had passed over them. This does happen sometimes in normal working conditions but the risk of this happening at the time of the accident had possibly been increased due to the environmental conditions causing the side plates to be dry or contaminated.
A visual indicator located alongside the points, which was showing that the points were not in the correct position was not observed by the driver of the tram. The driver believed that he would be informed if there were any issues with a set of points but had not been on this occasion. They had probably become conditioned to there being no issues at this location and was also possibly distracted.
As part of the investigation, RAIB concluded that Nottingham Trams Limited did not have an effective policy in place to inform drivers of points failures and had not specifically assessed the risk of a driver incorrectly passing a lineside indicator.
RAIB also observed that the process they used when introducing a new system to the tram fleet hadn’t considered the effect the change may have on its drivers. This relates to the fitting of a driver vigilance system which was in use on 232 at the time. Nottingham Trams Limited were also in the process of introducing a new speed control system although this wasn’t operational at the time of the accident.
Recommendations
Three recommendations have been made to Nottingham Trams Limited:
- Review of control room policy and procedures to ensure that clear and practical guidance is available to manage the response to engineering faults
- Improvement of risk assessments in light of this accident
- Consideration of human factors when assessing the effects of a proposed engineering change
There is also a learning point to remind tram drivers to not make assumptions about the status of signals or indicators based on their previous experience.
- The full report can be downloaded from the RAIB website at https://assets.publishing.service.gov.uk/media/6602efa565ca2f8e6b7da812/R022024_240327_Bulwell.pdf