A report is set to be published into last week's Croydon tram crash which killed seven people.
The Rail Accident Investigation Branch (RAIB) will publish its initial findings into why the two-carriage tram came off the track and fell onto its side in south London on November 9.
The derailment in the morning rush killed six men and one woman, leaving more than 50 injured.
An RAIB spokesman last week said the tram was travelling at "significantly higher speed" than the 12mph limit for that section of track.
The driver, Alfred Dorris, 42, was arrested at the scene on suspicion of manslaughter, but later released on bail.
It is understood that establishing whether Mr Dorris blacked out or was asleep are lines of inquiry.
The victims of the crash were named as 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.
Transport for London has offered to pay for their funerals, and said they will do "everything we can to support the families and all those affected".
Mike Brown, London's Transport Commissioner, said: "The TfL Sarah Hope line is available 24 hours a day to provide advice on a whole range of matters and immediate financial and other support."