TRAM operators failed to understand the risk of carriages overturning on curves, investigators said yesterday in the report into a crash which killed eight people.

Train drivers’ union Aslef put the accident down to a “failure of regulation and management,” saying that it could have been avoided.

The derailment occurred on November 9 last year, at Sandilands junction on the Croydon Tramlink network. The tram was travelling at 73kph (just above 45mph) — over the 20kph (12.5mph) speed limit.

The Rail Accident Investigation Branch inquiry concluded that it was likely the driver had “temporarily lost awareness on a section of route on which his workload was low.” It was possible, inspectors said, the driver “had a microsleep” as a result of fatigue.

There was no mechanism for automatic brake application, and “inadequate signage” warning drivers of the approaching sharp curve, the report said.

It recommends rectifying both deficiencies, as well as strengthening doors and windows. All of the passengers killed fell through the glass as the tram tipped over.

Chief inspector of rail accidents Simon French said: “There need to be improvements to safety management systems, particularly encouraging a culture in which everyone feels able to report their own mistakes.”

Aslef Tramlink organiser Finn Brennan said the recommendations were “long overdue.”

He said: “From its inception, the Croydon Tramlink system was treated as a ‘bus on rails.’

“If the same standards used for toughened glass on main line or light-rail vehicles were used in the construction of trams, then the deaths and most serious injuries could have been avoided.

“Drivers still fear their job is at risk if they report being tired or that they will be disciplined for reporting sick.”