Its name comes from the initial name given to the Hamburg metro system, Hochbahn (German: elevated railway).

After the acquisition of the Straßen-Eisenbahn-Gesellschaft (SEG) in 1919 and the Hamburg-Altonaer-Centralbahngesellschaft AG in 1923, the HHA had a rolling stock of 865 power cars and 930 trailers by 1928.

In spite of the "U" for "underground", large portions, especially outside the inner city, run on the surface.

BeNEX GmbH is the holding company for public transport corporations outside of Hamburg.

[3] Through BeNEX the Hamburger Hochbahn owns 25.1% of the Metronom Eisenbahngesellschaft, a company operating commuter trains in northern Germany.