Train Derailment Investigation Focuses on Welding and Track Maintenance
Adamuz, Córdoba – Investigations into the January 18th train collision near Adamuz, Córdoba, which resulted in 46 fatalities and 122 injuries, are centering on a possible fracture in a rail weld and broader questions of track maintenance, according to officials. A team of five investigators from the Commission for Railway Accident Investigation (CIAF) is leading the technical inquiry, supported by external analysts, and laboratories.
The CIAF is securing key evidence in coordination with the Guardia Civil and the Montoro court, and is requesting documentation from Adif, the infrastructure manager, and the train operators. Investigators are examining a weld between a rail dating from 1989 and a newer rail from 2023, reportedly identifying it as a potential point of failure. All evidence, including the weld, is being held in a secured room with access restricted to a single individual and requiring a signed protocol for entry, according to CIAF President Íñigo Barrón.
The judge overseeing the investigation, Carmen Troyano of the Montoro Court of Instruction number 2, will validate the laboratory chosen to analyze fragments of the track and the suspect weld in the coming days. She is scheduled to be replaced by Cristina Pastor Recover on February 9th. The pace of the Guardia Civil’s work is also dependent on the judges’ decisions.
While the judicial process will determine potential criminal responsibility, the technical investigation aims to offer recommendations to prevent similar tragedies. Experts consulted anticipate that recommendations will include increased distance between tracks – potentially a minimum of 5 meters between axes on new lines – and improved protection for train bogies. Barrón reportedly suggested increasing the distance between tracks could reduce the risk of collision in the event of a derailment.
Investigators are also examining the use of embedded alerting devices on trains. The possibility of equipping trains with large, autonomously powered warning lights to improve nighttime visibility is being considered as a potential recommendation.
The investigation is also looking at the safety system LZB, unique to the Madrid-Sevilla high-speed line, which allows train drivers to activate track blocking in emergencies. The newer ERTMS level 2 system lacks this feature, though it wouldn’t have prevented the Adamuz collision, as the Iryo train derailed nine seconds before the impact with the Alvia train.
Standardization of communications between train drivers and control centers, and ensuring that reports of incidents from train drivers are carefully reviewed, are also under consideration. Experts emphasize the importance of analyzing impacts and vibrations as indicators of potential track issues.
The use of fiber optics as acoustic sensors to detect rail defects is also being explored. Adif has already implemented similar technology in projects to monitor slopes and detect obstructions on the tracks.
The investigation is also scrutinizing the scope of track renewal projects, such as the “integral renovation” underway on the Madrid-Sevilla line between 2022 and 2025. A previous derailment in 2017 on the same line prompted the CIAF to raise concerns about inconsistencies in safety criteria and inadequate maintenance practices.
Further scrutiny is being applied to the welding process itself, including how the suspect weld was executed on May 25, 2025, and the thoroughness of subsequent inspections using visual, ultrasonic, and liquid penetrant methods. The investigation will also examine the origin of the rail that broke away, manufactured by ArcelorMittal in Gijón in 2023.
Transport Minister Óscar Puente has indicated openness to discussing increased investment in track maintenance, noting a rise in spending from 759 million euros in 2011 to 1.120 billion euros in 2025. This increase coincides with the opening of new high-speed lines across Spain.
In parallel with the technical investigation, the Guardia Civil is conducting a criminal investigation, having already interviewed the drivers and crew of both trains, as well as passengers. The Guardia Civil collected over 2,500 photographs of the accident site and has created a 3D reconstruction of the events.
