Spain high-speed crash: possible rail break detected 22 hours before accident, but no alert triggered

Spain’s infrastructure manager Adif picked up signs of a possible rail break on the track near Adamuz almost 22 hours before the deadly high-speed crash, but the alert was not triggered due to a “configuration” problem, according to a new report from Spanish law enforcement.

Adif’s signalling systems detected a potential rail break nearly a day before the fatal Adamuz accident in January, according to a new Civil Guard investigation report on the Adamuz crash. However, the warning signs failed to prompt an alert or a response that could have helped avert Spain’s deadliest rail accident in a decade.

The findings, which confirm that the investigation is now focused on a single technical cause, either a broken rail or a defective weld, were first reported by Spanish newspaper El Mundo, which had access to the document. According to the report, investigators recorded an electrical disturbance “consistent with a break” at 21:46 on January 17, the evening before the crash. The report states that 21 hours and 57 minutes elapsed between the initial fault detection and the accident, in which an Iryo train derailed and was subsequently struck by a Renfe service, killing 46 people and injuring hundreds.

The Civil Guard’s findings show that the signalling system supplied by Hitachi Rail did not generate any warning because it “was not configured to alert automatically due to a lack of reliability.” This meant that despite detecting an anomaly in the track circuit, no preventive action was taken to stop traffic over the affected section.

A question of volts

Electrical data analysed by investigators shows that track voltage, typically around two volts, dropped to 1.5 volts from the moment the disturbance was recorded on January 17. That reduced level persisted for nearly a full day, eventually reaching zero at the time of the accident at 19:43 on January 18.

Investigators say the drop persisted “in a sustained manner over time” and was not typical of the normal data recorded in the days leading up to the crash. Despite this, the anomaly did not trigger any automatic alert within Adif’s systems.

Instead, the data was simply stored in the SAM (Maintenance Assistance System) at the Hornachuelos maintenance base in Córdoba, where it would normally only be reviewed during maintenance operations or after a reported failure. As El Mundo reports, investigators are now examining whether an alert should have been technically generated, particularly given the duration of the anomaly and “the severity of the consequences.”

Hitachi blames process, not technology

Hitachi Rail GTS Spain, the supplier responsible for the signalling system, said in a statement that while detecting a rail break was technically possible, the system would only issue an alert if the voltage dropped below 0.780 volts, the defined occupancy threshold.

In the Adamuz case, the voltage at the initial sign of a possible break fell only to 1.5 volts, remaining above that threshold and therefore not triggering any warning. In its explanation to investigators, Hitachi stressed that “the system design must include the ability to detect rail breaks,” suggesting that the issue was not simply whether the signalling equipment had that capability, but how the wider detection setup had been implemented.

To support that point, a Hitachi representative cited a Renfe memorandum stating that “the track clearance signalling equipment requires a minimal number of connections between rails and the return system in order to detect a rail break,” effectively arguing that detection depends on the track being electrically set up to make a break visible to the system. The same document adds that “the grounding of the poles must be coordinated with the signaling technology for the detection of possible rail breaks,” meaning the warning function also depends on how the wider infrastructure is grounded and integrated, not just on the signalling equipment itself.

Who was on the ground?

Beyond the signalling system itself, the investigation is also examining track maintenance procedures, with the Civil Guard report raising “doubts regarding their certification in terms of training” concerning the two technicians who carried out ultrasonic inspections on the weld now under scrutiny. It also states that there is a requirement for “welding inspectors to be present during welding work,” while statements gathered so far indicate that these inspectors “were not present during the work.” Investigators are reportedly continuing to verify those claims.