A fracture in a straight section of track occurred prior to the passage of a high-speed train that derailed, causing last Sunday's rail disaster in which 45 people died, an initial report has found.
A train run by private company Iryo derailed last Sunday and its rear carriages crossed onto the opposite track into the path of an oncoming train run by state-owned Renfe.
The CIAF rail investigation commission said not only did the Iryo train's front carriages, which stayed on the track, have notches in their wheels, but three earlier trains that went over the track had similar issues.
A gap of almost 40cm (15in) in the track has become the focus of the investigation into the crash.
Sunday's deadly collision occurred at around 19:45 local time (18:45 GMT), about an hour after the Iryo train left Málaga for Madrid.
The train's last three carriages - carriages six to eight - derailed and collided with the Huelva-bound Renfe train. Carriage six derailed due to a complete lack of continuity in the track, the preliminary report finds.
Most of those killed and injured were in the front carriages of the state-operated train.
Earlier this week, Spanish Transport Minister Óscar Puente confirmed reports that grooves were found on the wheels of the Iryo train's carriages, which had passed over the track safely.
These notches in the wheels and the deformation observed in the track are compatible with the fact that the track was cracked, the CIAF preliminary report said.
The Adamuz disaster is the country's worst rail crash in more than a decade, reminding us of the tragic 2013 derailment in Galicia that left 80 dead.
