A tram which crashed in Croydon, south London, killing seven people was travelling at three-and-a-half times the speed limit when it derailed, accident investigators have said.
An interim report by the Rail Accident Investigation Branch (RAIB) found that the vehicle was doing approximately 44mph as it entered a sharp bend with a 12mph limit.
The tram derailed and overturned as it approached Sandilands Junction at 6.07am on Wednesday November 9.
The investigation has found no evidence of track defects or a malfunction of the tram's braking system.
The RAIB issued "urgent safety advice" to First Group, which carries out the day-to-day operation of the trams, and Transport for London, which manages the overall performance of the network.
Both organisations were urged to take measures to reduce the risk of trams approaching the location of the crash "at an excessive speed" once the line is reopened.
This could be done with a further speed restriction before the start of the 12mph limit and additional warning signs, the report suggested.
The tram's driver, Alfred Dorris, 42, from Beckenham, south-east London, was arrested at the scene and was questioned on suspicion of manslaughter before being bailed until May.
A spokeswoman for First Group said he had worked at the company since March 2008.
It is understood that establishing if Mr Dorris was asleep or had blacked out are lines of inquiry.
The seven people killed in the crash were Dane Chinnery, 19, Philip Logan, 52, Philip Seary, 57, Dorota Rynkiewicz, 35, and Robert Huxley, 63, all from New Addington, and Mark Smith, 35, and Donald Collett, 62, both from Croydon.
A further 51 people were taken to hospital, with eight of them suffering injuries described by London Ambulance Service as serious or life-threatening.
Chief Inspector of Rail Accidents Simon French said he would be in contact with the casualties and the families of those who died to keep them updated throughout the investigation "which will take some months to complete".
He went on: "Our ongoing detailed investigation will now look at the wider context of the accident, including the sequence of events, the way the tram was driven, the infrastructure and how people received their injuries.
"We will also be looking into previous occurrences of over-speeding in this area and underlying management issues.
"Our final report will include recommendations to reduce the likelihood and consequences of similar events occurring in the future."