The bus service in central Saarbrücken then ran at such a high density that the vehicles sometimes operated at one-minute intervals.

Following the example of the Karlsruhe model, which had operated with great success since 1992, the Saarland began to plan to build a regional Stadtbahn.

As early as 1992, it borrowed a light rail vehicle from the Karlsruhe Stadtbahn and ran it on the Fürstenhausen–Gersweiler Bahnhof–Saarbrücken Messebahnhof route on the Rossel Valley Railway (Rosseltalbahn), south of the Saar.

This forward operation began on 29 September 1997 and ended on 24 October 1997, the opening day of the new line through the city centre.

Saarbahn railcars coming from central Saarbrücken change from 750 V DC to 15 kV  16+2⁄3 Hz AC and run via Kleinblittersdorf to Sarreguemines, Lorraine.

The first light rail vehicle that reached Saarguemines was two-system railcar 810 of the Albtal-Verkehrs-Gesellschaft (AVG), which ran there on 11 September 1993 during a presentation ride.

[8] After the new section between Riegelsberg-Güchenbach and Walpershofen/Etzenhofen, the Saarbahn reaches, at the Walpershofen/Etzenhofen stop, the line of the former Koller Valley Railway, over which it continues north through Walpershofen to its temporary terminus at Heusweiler Markt.

[2] Currently the 44.0-kilometre (27.3 mi)[2] cross-city route is operated as line S1 between Heusweiler Markt and Sarreguemines, with services every 7.5 minutes during the day on the core section between Siedlerheim and Brebach station.

Originally, a five-minute interval service was planned for the central area, but this was rejected because it would have led to operational problems.

Another proposal would include an extension via Burbach to Völklingen station, but this plan has been put on hold, as the effects of mining have to be remedied first.