Trams have operated continuously in Darmstadt since 1886, with the opening of a steam tram line. The network has been operated since 1912 by Hessische Eisenbahn-Aktiengesellschaft (HEAG) either directly, or, more recently, through one of its subsidiaries. Since then the trams have become a distinctive part of Darmstadt's character and are widely used by people from all walks of life as a safe and fast way of transportation within Darmstadt and its suburbs. At the Hauptbahnhof station the tram system and the Frankfurt S-Bahn-System meet. While some older lines like the Oberwaldhaus-/Martinsviertel-/and Ostbahnhof lines were closed, new sections were built, following the development of new residential areas, e.g. the new lines to Kranichstein, Arheilgen north and Alsbach south. Since the 1990s the tram system has gradually been modernised. All lines (except for line 3) have since been less of a classical tram and more of a light rail transit system with a private right-of-way and separate stations with "same-level-platforms".
The central hub of the Darmstadt tram network is the "Luisenplatz", at which eight of Darmstadt's nine tram lines stop. On the main routes the hours of operation are usually from around 5:00 am until 1:00 am. The network is currently made up of the following lines:
All lines run – unless otherwise stated – at 15-minute intervals (at night and on Sunday mornings at 30-minute intervals). On the southern route between Eberstadt and Alsbach, service intervals are 15 minutes during peak hours and 30 minutes in the evenings. Since many stations are being served by more than one line, service intervals are 3 to 7 minutes at the central stations, especially in the city centre.
Bürnheim, Hermann; Burmeister, Jürgen (1997). Bahnen und Busse rund um den langen Ludwig. (Engl.: Railways and Buses around the long Ludwig) (4th ed.). Düsseldorf: Alba Publikation. ISBN 3-87094-357-2. (German)
Höltge, Dieter; Köhler, Günter H. (1992). Straßen- und Stadtbahnen in Deutschland [Tramways and Stadtbahnen in Germany]. Band 1: Hessen [Volume 1: Hesse] (2nd., enlarged ed.). Freiburg i. B., Germany: EK-Verlag. ISBN3882553359.(German)
Höltge, Dieter; Köhler, Günter H. (1992). Straßen- und Stadtbahnen in Deutschland (Engl.:Tramways and Stadtbahnen in Germany). Volume 1: Hesse] (2nd., enlarged ed.). Freiburg i. B., Germany: EK-Verlag. ISBN 3882553359. (German)
Schwandl, Robert (2012). Schwandl's Tram Atlas Deutschland (3rd ed.). Berlin: Robert Schwandl Verlag. ISBN 9783936573336.