The Rail Accident boss from Network Rail says that investigators have 'downloaded data from a black box' from the derailed Croydon tram.

...we carried out a detailed investigation of the site, measurements on the site, a download of the tram's on tram data recorder - often known as a black box - and also carried out some preliminary analysis of the sequence of events.

Simon French, Chief Inspector, Rail Accident Investigation Branch Mark Carne, Chief Executive, Network Rail