[ Bonn ] == train ==> [ Berlin ]
[ Bonn ] -- car --> [ Potsdam ]
[ Berlin ] .. bus ..> [ Potsdam ]
[ Berlin ] .- bike .-> [ Ulm ]
[ Bonn ] == train ==> [ Berlin ]
[ Bonn ] -- car --> [ Potsdam ]
[ Berlin ] .. bus ..> [ Potsdam ]
[ Berlin ] .- bike .-> [ Ulm ]