The French Land Transport Accident Investigation Bureau^[1] (Bureau d'Enquêtes sur les Accidents de Transport Terrestre, abbreviated BEA-TT) is an agency of the French government formed in 2004 and charged with the investigation into accidents involving all forms of land transport, including railways, urban guided transportation systems (metros, trams), cable-hauled transport systems, road transport (heavy goods vehicles, and public transport by coach and bus), and canals and other navigable inland waterways.^[2] It is headquartered in the Tour Voltaire [fr] in La Défense business district in Puteaux.^[3]

Prior to the formation of the BEA-TT, the government minister with responsibility for transportation would set up ad hoc investigation commissions, for example after the 1988 Paris-Gare de Lyon rail accident and 1999 Mont Blanc tunnel fire. These commissions were supported by the Conseil Général des Ponts et Chaussées (CGPC, "Civil Engineering General Council").^[2]

The CGPC's experience, particularly following the Mont Blanc tunnel fire, showed there was a need for a new legal framework that guaranteed investigators access to sites, recordings and information covered by commercial confidentiality or pre-trial non-disclosure agreements.^[2] An Act of parliament passed on 3 January 2002 supplied the legal basis for technical investigations and reaffirms and mandates the investigatory principals of independence, and commits to the publishing of the report. The BEA-TT was founded by a decree on 26 January 2004, with the right of access to all elements useful to an investigation, even those covered by non disclosure or confidentiality requirements such as those pre-trial or for commercial and medical reasons.^[2]

• Brétigny-sur-Orge train crash

• Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA)
• Bureau d'Enquêtes sur les Evénements de Mer (BEAmer)

• Road Safety Investigation Branch (Great-Britain)