The failure of the line's main signaling system and the subsequent decision to resume service manually are at the centre of the early findings on the train collision in Toledo, which may have been triggered by human error, according to Spanish government sources, as reported by El País.

Eight trains were brought to a halt in the area after the failure; the control center then switched to manual operation and instructed all trains to resume their journeys. Spain's transport minister pointed to an “inexplicable” decision as a possible cause of the collision, according to Xinhua.