On the centenary of the Harzquerbahn in 1999, HSB and Stadtwerke Nordhausen stated their intent to connect the railway and tram systems.

Dubbed the Twino, it was a GT4 railcar fitted with a five-cylinder passenger car diesel engine, and was used for practical testing of dual-power operation.

[7] In December 2001 three Combino Duo trams were ordered,[4] fitted with BMW M67 3.9-litre twin-turbocharged V8 engines.

It follows the course of route 1 from the Südharz Klinikum hospital through Nordhausen town centre to the station forecourt, and then along the Harzquerbahn track as far as Ilfeld Neanderklinik, a distance of 11.4 km.

The Combino Duo trams are fitted with a diesel engine to allow operation on the unelectrified section of tram-train line 10 on the Harzquerbahn.