Karlsruhe's Nuclear Research Center is a secluded facility in the middle of a forest north of the city. To facilitate commuting, this extensive research complex is served by a dedicated branch of the Karlsruhe Stadtbahn system. Usually, this line is served by just two morning trains and two afternoon trains, all closed to the public, like the facility itself - but every couple of years, there is a chance to ride this line (and take photos of it) for the general public on Open Day events.
(17 June 2023)