Explained in plain English

Who investigates train crashes?

When a train derails, like the one near Rouen, it triggers a detailed investigation. In France, this is typically handled by the Bureau d'Enquêtes sur les Accidents de Transport Terrestres (BEA-TT), a specialist body. Their job is to find out exactly what happened, whether it was an object on the tracks, a mechanical fault, or something else, to prevent future incidents.