‘Microsleep’ possible cause of Croydon tram derailment

Photo: RAIB.

The driver of a Croydon tram that derailed, resulting in the deaths of seven passengers, may have had a “microsleep” moments before the crash, accident investigators have concluded.

The Rail Accident and Investigation Branch (RAIB) made 15 recommendations in its report into the Sandilands junction derailment.

On November 9, 2016, an early morning Croydon tram service derailed when it hit the 20 km/h bend at 73 km/h. In addition to the seven fatalities, 61 passengers were injured in the incident, 19 seriously.

The report concluded that the driver probably “lost awareness” prior to the derailment and then became confused about his location. The RAIB believes the incident was linked to fatigue, although not as a result of the driver’s shift pattern, and could have been caused by a microsleep.

The RAIB has recommended that the operator, Tram Operations Ltd (TOL), look into technology that can monitor driver alertness and automatically apply the brakes if a tram is going too fast – neither of which were available at the time.

During the investigation, the RAIB ran computer simulations that confirmed that the tram would have derailed at any speed above 49 km/h (30 mph). It said better signage was also required to remind drivers when to start braking.

The report also recommended creating a dedicated safety body for the UK’s tram networks.

Recommendation areas

  • technology, such as automatic braking and systems to monitor driver alertness
  • better understanding the risks associated with tramway operations, particularly when the tramway is not on a road, and the production of guidance on how these risks should be managed
  • improving the strength of doors and windows
  • improvements to safety management systems, particularly encouraging a culture in which everyone feels able to report their own mistakes
  • improvements to the tram operator’s safety management arrangements so as to encourage staff to report their own mistakes and other safety issues
  • reviewing how tramways are regulated
  • a dedicated safety body for UK tramways

The investigation found a blame culture within TOL and discovered that earlier late braking incidents at the same junction hadn’t been reported.

Analysis of the incident showed that the main cause of death and injuries was passengers being thrown from the tram. The RAIB recommended tram owners and operators look at how they can strengthen doors and windows to keep passengers contained within trams during similar incidents.

Simon French, chief inspector of rail accidents said: “The RAIB’s report into the accident at Sandilands will stand as the record of the events that led to the tram overturning and the terrible human consequences. Our careful analysis of the evidence, and identification of the causal and underlying factors, has enabled us to make a number of far-reaching recommendations. These will have a lasting impact on the way that the tramway industry manages its risk.

“We are recommending action in five main areas. The first is the use of modern technology to intervene when trams approach hazardous features too fast, or when drivers lose awareness of the driving task.

“Tramways need to promote better awareness and management of the risk associated with tramway operations. Work needs to be done to reduce the extent of injuries caused to passengers in serious tram accidents, and to make it easier for them to escape. There need to be improvements to safety management systems, particularly encouraging a culture in which everyone feels able to report their own mistakes.

“Finally, greater collaboration is needed across the tramway industry on matters relating to safety.

“UK tramways have been aware of our key findings and the focus of our recommendations for many months now. I am very encouraged by the progress that has already been made in addressing the recommendations and the collaborative approach that is being taken.

“It is vital that the right action is taken to stop such a tragic accident from ever happening again.”

TfL response

In a statement, Mike Brown MVO, London’s Transport Commissioner, said: “Our thoughts remain with those who lost their lives or were injured in the tragedy at Sandilands, and we continue to do all we can to support everyone affected.

“We welcome this report from the Rail Accident Investigation Branch and will continue to work alongside them, the Office of Rail and Road and First Group, who operate the tram network, to ensure all of the recommendations outlined are met. We will also be publishing our own investigation report in the new year.

“Since the incident we have introduced a wide range of additional safety measures to make sure such a tragedy can never happen again. These include new signage and warning systems for drivers, additional speed restrictions, enhanced speed monitoring and an upgrade of the CCTV recording system.

“An in-cab driver protection device has been trialled and is now fitted to every tram, meaning that any sign of driver distraction or fatigue results in the driver being alerted immediately. Work to install a system to automatically reduce tram speeds if required is also underway.

“We have enhanced the customer complaints process so that all reports are now managed by one dedicated TfL team and any that relate to safety are prioritised for immediate investigation. And the TfL Sarah Hope line remains available to all those affected and continues to provide help with counselling and other support to anyone who needs it.

“We also continue to work with the wider tram industry to ensure that lessons are learned from this incident and that we introduce any further measures that could improve the safety of trams across the UK.”

FirstGroup response

Tim O’Toole, FirstGroup’s chief executive officer, said: “The tragic incident on the Tramlink network in November 2016 deeply shocked and saddened us all. We are profoundly sorry that such an incident could take place aboard a service we operate and on behalf of everyone at FirstGroup, I would like to reiterate our condolences to the families and friends of those who lost their lives, and all those who were injured and affected by this terrible event.

“I would like to thank the Rail Accident Investigation Branch for their thorough report into the incident. We are grateful for their recommendations for improvements to the system in Croydon and tram networks across the UK.

“The RAIB concluded that management of fatigue was not a factor in the incident, nor did a speeding culture contribute to it. Nevertheless, over the past year we have taken a series of actions, working closely with Transport for London on whose behalf we operate the system, to implement additional measures including enhanced speed monitoring and restrictions, improved signage and renewed guidance on fatigue management.

“We have learned from the RAIB’s analysis and our own internal reviews and we will continue working hard, alongside TfL, to follow the RAIB’s advice and to make further changes where necessary.

“Our commitment to the safety of our passengers, our employees and other parties who engage with us is unwavering. Safety is a core value for FirstGroup and central to our culture as a company.”

The driver of the tram remains on police bail.

Clarification: The tram was travelling at 73 km/h on a 20 km/h junction not a 30 mph junction. The report refers to evidence that any speed above 30 mph would have resulted in a derailment.


  1. The accident could of been prevented if the driver was to stop his job due to fatigue and to allow another driver to operate that tram then the accident wouldn’t happen.


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