Duisburg lies on the confluence of the Ruhr and the Rhine rivers and has 500,000 inhabitants but quite a small Stadtbahn network compared to its neighbouring cities Essen or Dortmund, which are all intergrated in the VRR tariff system (Verkehrsverbund Rhein Ruhr). The general Rhein-Ruhr Stadtbahn network designed in 1970 included two routes for the Duisburg area, one east-west linked to Mülheim and another one north-south linked to Düsseldorf.

In the early 1970s, the former interurban tramway D between Duisburg and Düsseldorf was upgraded to Stadtbahn standard with high platforms and mainly separate right-of-way. In the city centre of Duisburg, trams remained on streets for another 20 years as construction of the underground section was delayed due to financial problems.

The inner-city stations König-Heinrich-Platz and Duisburg Hauptbahnhof finally opened on 11 July 1992 and were designed for more underground traffic in the future: both stations have two platform levels with tram line 901 on the lower level at König-Heinrich-Platz and cross-platform interchange in each direction at Duisburg Hauptbahnhof. Platforms used by U79 and tram 903 have a low section for the tram. A 3.6 km extension of the Stadtbahn tunnel from Duissern north under the river Ruhr to Meiderich opened on 23 Sept 2000. This route is served by tram 903 and by line U79 from Düsseldorf.

STADTBAHN (U79)
- Line length on Duisburg territory: 17 km
- Rolling stock: DUEWAG B cars (high floor; 1983-85)

TRAM (901, 903 - 1435 mm gauge)
- Route length on Duisburg & Dinslaken territory - 43.7 km (of which 7.5 km are shared with Stadtbahn line U79)
- Rolling stock: GT10NC-DU (low-floor middle section; 1986-93)
- Bombardier Flexity on order for delivery from 2019

11 July 1992: [Ramp] - Steinsche Gasse / [Ramp] Rathaus - Duissern

23 Sept 2000: Duissern - Meiderich Bahnhof

DVG - Duisburger Verkehrsgesellschaft (Official Page)

Straßenbahn Duisburg & Stadtbahn Duisburg at Wikipedia.de

Stadtbahn Rhein-Ruhr by Jochen Schönfisch

Straßenbahn Duisburg

Duisburg Tram Track Map at gleisplanweb.de