Experts link Adamuz accident to defect in roads known to Adif since October 2025

The Adamuz railway accident, in which 46 people died and more than a hundred were injured, was due, among other factors, to a defect in the tracks just at the kilometer point where they broke, causing the derailment of the last carriages of the Alvia that was heading to Huelva from Madrid and which then collided with the Iryo that came from Malaga. And Adif, the public company responsible for railway infrastructure, was aware of this defect, at least since October 2025, four months before the tragedy, which occurred on January 18.

This is one of the first conclusions reached by the independent experts appointed by the Montoro judge who is investigating the incident so that they can determine, in parallel with the Civil Guard, what happened and, above all, why it happened.

In response to an order from Judge Cristina Pastor, the experts Ramón Ignacio Martínez, José Antonio Martínez and Miguel Ángel Moraleda are forceful when it comes to linking the breakage of the left thread of the rail with a longitudinal leveling defect, a pothole, of -6.4 millimeters in the right internal thread and at the exact point of the break, kilometer point 318+682, which was classified with an alert level AL (the lowest), so that only "preventive maintenance."

The experts point out, in a letter to the judge to which EL MUNDO has had access, that "the interaction between both rails is constant due to the rigidity of the axles of this type of trains and the transfer of loads through the sleepers, producing amplification of the damage due to fatigue."

Furthermore, experts explain that the effect of this pothole consisted of "cyclical vertical impacts" for a prolonged period of time that could produce an amplification of the fatigue damage of the material "in its weakest area", the weld between two sections, which was the one that failed.

If this conclusion appeals directly to Adif's responsibility in maintaining the infrastructure, the public company dependent on the Ministry of Transportation is even more pointed out by the experts when they affirm that if the defect, the pothole, was not corrected, the effect on the other thread was increasing. They add, measures should have been taken to prevent it.

The impact of this bump in the right thread on the fracture of the aluminothermal weld of the left thread is beyond any doubt for the experts appointed by the head of the Civil and Investigation Section of the Court of Instance of Montoro 2, who emphasize in their document that "the welds are the weakest part of the mixed structure formed by the rails and sleepers." Even a pore, an invisible microdefect, accelerates the fatigue of the material, they point out, and that can cause the microcracks to propagate rapidly until fracturing the union of the rails.

But the defect in the right thread of the rail, right at the point where the Alvia 2384 derailed, is not the only factor highlighted in this first statement by the experts on the Adamuz tragedy. The welding between two sections of track, one from 1989 and the other from 2023, at that same point has been, from the beginning, the objective of the investigators and these experts confirm the suspicions that there could have been another negligence with fatal consequences.

They claim that the completion of the weld was not "optimal", since its level of flatness was 0.14 millimeters, very close to the maximum allowable limit, which is between 0.15 and 0.20 for speeds greater than 250 kilometers per hour.

Regarding this welding, in addition, there were already previous doubts about the method used to join sections of tracks of different ages, something that was done in renovation works promoted by Adif in mid-2025. Doubts were amplified by the supposed corrections in the welding reports, in which incorrect actions were first reflected to weld sections of such different ages and, subsequently, they were rectified.

In this regard, both the president of Adif, Luis Pedro Marco, and the Minister of Transport, Óscar Puente, downplayed these rectifications at the time and attributed the original certifications to an "error."

The Civil Guard itself draws attention to this issue in previous reports on the changing information around key welding traceability. The original work report completed by the welder in May 2025 stated that he had applied an incorrect method to join material from 2023 with material from 1989.

But on January 29, 10 days after the accident and with the welding already in focus, an inspector corrects the report with an errata that indicates that the welder confused the certification labels.

The experts conclude that "it is not normal" for a road renovated just a few months earlier to present defects such as those found.

There is still another question on which the experts stop, in response to questions from the judge. Specifically, on the surveillance and incident detection systems on the road. In the opinion of these three experts, there were indications that should have set off the alarms before the incident, such as exceeding certain levels in the vertical acceleration of the axle box (the mechanical element at each end of the axle of a set of wheels that contains the bearings that allow it to rotate), which yielded "high" values ​​and therefore required "intense control."

Added to this is the fact that it is "technologically possible" to have a track break detection protocol that Adif's infrastructure did not have.