Spain's national rail operator Renfe (Red Nacional de los Ferrocarriles Españoles) triggered safety protocols in late March after discovering small linear marks on the wheels of several Alvia trains running the Madrid–Zafra route in western Spain. The company has sought to distinguish the findings from a more serious incident in January, when a train derailed near Adamuz, Córdoba, leaving deep coin-shaped notches on multiple sets of wheels — an accident now believed to have been caused by a fractured rail or weld. Renfe and infrastructure manager Adif say no new markings have been detected since inspections were intensified, no track anomalies have been found, and periodic reviews will continue as a precaution.