A report is due to be published into the 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 tracks in south London, killing six men and one woman, and leaving more than 50 injured.
The tram derailed on a tight bend before flipping on to its side during the morning rush on November 9.
An RAIB spokesman revealed last week that the vehicle was travelling at a "significantly higher speed" than the 12mph limit for that section of the network.
The organisation's interim report will be published on Wednesday afternoon with a full report not expected for several months.
The tram's driver, Alfred Dorris, 42, from Beckenham, south London, was arrested at the scene and was questioned on suspicion of manslaughter before being bailed until May.
A spokeswoman for First Group, which carries out the day-to-day operation of the trams, 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 contents of a so-called black box data recorder on the tram were downloaded by investigators.
The seven victims of 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.
Transport for London has offered to pay for the funerals, pledging to do "everything we can to support the families and all those affected".
Mike Brown, London's Transport Commissioner, said: "This includes covering funeral costs and travel expenses for relatives.
"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."