ADIF - Spain
More and more "gauge changing boxes" appear on the Spanish network. In such a box, while running at about 10km/h, the distance between the wheels of the train is changed from 1668mm (Spanish broad gauge) to 1435mm (European standard gauge) or vice versa. The Spanish high-speed lines are built in standard gauge.
The "Cambiador" on the picture is located just south of Madrid Atocha station.
Madrid, 21-05-2015

Digital photo by Marco van Uden