In the Board of Trade's post-accident inquiry, Carlisle was very clear as to why White Star declined to install extra lifeboats: The firm wanted to see whether regulators required it.
The NTSB says the Washington Metropolitan Area Transit Authority reported the problem during a post-accident review of track circuit data, but it was not immediately clear if operators were aware of the problem before the accident.
The death, which happened on 12 July 2010, was initially treated as an accident until a post-mortem examination found the boy was dead before the blaze began.