A charity worker who was nearly twice the drink-drive limit died of a head injury after leaning out of a train window at 75mph.
Bethan Roper, 28, hit a tree branch on the Great Western Railway service near Bath after a Christmas shopping trip with friends on December 1.
Network Rail had not carried out a tree inspection at the scene since 2009, a report by the Rail Accident Investigation Branch (RAIB) revealed on Wednesday.
It also said a notice on the train door had failed to convey how dangerous it was to lean out of the window.
