Here's the rule from the transit system in Berlin: "Children under four years of age may only use public transport if they are accompanied by a person who is a

Here's the rule from the transit system in Berlin: "Children under four years of age may only use public transport if they are accompanied by a person who is at least six years of age." https://www.bvg.de/en/Tickets/fare-overview/conditions-of-carriage https://www.bvg.de/en/Tickets/fare-overview/conditions-of-ca...