Rail Accident Investigation Branch
The RAIB is an organisation with responsibility for independently investigating railway accidents with the aim of improving safety. RAIB's work covers all UK railways all  and tramways in England and Wales.  It is part of the Department for Transport, but functionally and operationally independent. The Chief Inspector reports directly to the Secretary of State on accident investigations.[1]

The responsibilities of the RAIB are set out in the Railways and Transport Safety Act 2003 (the Act) and the Railways (Accident Investigation and Reporting) Regulations 2005.