Nottingham trap-and-drag: inadequate risk assessment

Inadequate risk assessment by Nottingham Trams was the probable underlying cause of an incident on December 15 2017, when an empty pushchair became trapped on the outside of a tram at the Radford Road stop.

The pushchair’s plastic rain cover was caught between closing doors, and the pushchair was dragged to the next tram stop where it was crushed against the kerb. Nobody was injured in the incident.

A Rail Accident Investigation Branch (RAIB) investigation found that the rain cover was too thin to trigger the door obstruction system, and that the driver was unaware during his final visual door check that the pushchair was in an unsafe position.

A modification to the tram’s CCTV system meant that a larger image of the pushchair was unavailable to the driver. The travel officer and other staff at the tram stop were unable to stop the tram departing, and the driver remained unaware of the pushchair until the next stop.

RAIB said staff placed “inappropriate reliance” on the doors closed indication, and that other factors included a lack of awareness of the importance of the final door visual check and the way in which the CCTV arrangements had been modified. It said the incident also showed that training of travel officers was inadequate.

The CCTV cameras on the outside of the trams were originally designed to show views from front and rear cameras on the platform side of the vehicle, and remain enabled until the tram had moved around 30 metres, at which point the rear platform side CCTV camera view switched to the nonplatform side front camera view, giving a ‘wing mirror’ view on the screen for use on the roads.

However, it was identified that this configuration was not compliant with road vehicle legislation, and the system was modified so that as soon as the doors were closed and locked the CCTV system would switch to the wing mirror view. RAIB concluded that had the driver been able to see the rear camera’s platform side view when the doors were locked, he would have had a better chance of noticing the pushchair as that camera gave a better view.

RAIB also found inadequate training of travel officers for removing groups of passengers from trams, and that the risk of objects being trapped in doors and of people being dragged along by a departing tram were not discussed during one travel officer’s training.

A passenger used the passenger alarm to talk to the driver, but did not get an answer. Examination of audio recordings showed that while a distressed passenger could be heard talking in the background, the nature of the distress was unclear.

Two recommendations were made in the RAIB report. The first is that Nottingham Trams should review and improve arrangements to manage the risk of trap-and-drag incidents during tram dispatch. Areas in which improvements should be considered include ensuring drivers have all the equipment needed for an effective final visual door check of all doors after interlock is achieved, CCTV modifications, investigation of door seal modifications, training of drivers, and training of travel officers.

The second is that the operator should review its risk assessment process to improve how it considers learning from the wider tramway and rail industries, give “explicit and detailed consideration” of the ways in which identified mitigation measures can fail and the consequences when this happens, and effectively evaluate the safety impact of changes to design and/or operational procedures.

RAIB said Nottingham Trams should update its tram operation risk assessments.