operational reserve. Those were retired on 28 November 2015 after being replaced by new DT5 trains. One non-refurbished unit is preserved for museum rides but has not been sent into restoration yet (2018). Network Map See also List of Hamburg U-Bahn stations Hamburg S-Bahn AKN railways plc Public transport in Hamburg Notes References External links Operator of the Hamburger U-Bahn Die Geschichte der Hamburger Hochbahn Book by André Loop Current and historical Plans for the U4 Hamburg's underground - a picture site at public-transport.net U-Bahn Underground rapid transit in Germany Railway lines opened in 1912 1912 establishments in Germany 750 V DC railway electrification