Expert: Speed may not be only factor

SANTIAGO DE COMPOSTELA, SPAIN - JULY 25: TV Journalists report from a vegetable plot near a train crash that killed at least 80 people on July 25, 2013 at Angrois near Santiago de Compostela, Spain. The crash occurred as the train approached the north-western Spanish city of Santiago de Compostela at 8.40pm on July 24th, at least 80 people have died and a further 131 reported injured. The crash occured on the eve of the Santiago de Compostela Festivities. (Photo by Pablo Blazquez Dominguez/Getty Images)
SANTIAGO DE COMPOSTELA, SPAIN - JULY 25: TV Journalists report from a vegetable plot near a train crash that killed at least 80 people on July 25, 2013 at Angrois near Santiago de Compostela, Spain. The crash occurred as the train approached the north-western Spanish city of Santiago de Compostela at 8.40pm on July 24th, at least 80 people have died and a further 131 reported injured. The crash occured on the eve of the Santiago de Compostela Festivities. (Photo by Pablo Blazquez Dominguez/Getty Images)

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