On January 24, 2023, a local newspaper in Asturias broke a strange story about Spain’s new narrow-gauge trains. Within days, it had escaped the railway pages and gone international: Spain had ordered new trains that were too big to fit through its own tunnels.
The problem involved the former FEVE narrow-gauge network in northern Spain, particularly services in Asturias and Cantabria. Renfe had ordered a new fleet from Spanish manufacturer CAF, only for a conflict to emerge between the train specifications and the clearances available through parts of the old infrastructure.
That sounds like the sort of engineering failure where dozens of brand-new trains are built, rolled out of the factory, and then discover the tunnel is smaller than the train. But that is not what happened. The problem was detected during the design stage, before manufacturing began. No train using the incompatible dimensions was ever completed.