The Rail Accident Investigation Branch (RAIB) is a British government agency that independently investigates rail accidents in the United Kingdom and the Channel Tunnel in order to find a cause, not to lay blame.

[3] Created in 2005, it is required by law to investigate accidents causing death, serious injuries or extensive damage.

[4][5] During 2003, Parliament legislated – in the Railways and Transport Safety Act 2003 – to create the RAIB as an independent body charged solely with establishing the facts of the case and assessing and evaluating causes, but not apportioning blame or establishing liability; nor does the RAIB enforce safety law or conduct prosecutions.

Whilst the police must always be involved when there may have been a crime, the involvement of HMRI as the principal safety investigating agency attracted criticism on the grounds that the HSE might be investigating itself, if, for example, the HSE had approved a track layout or a signalling scheme later suspected to have been at fault.

[11] The Farnborough/Aldershot centre is Cullen House, adjacent to the Air Accidents Investigation Branch head office.