The line runs northeast for about 700 metres (2,300 ft) from the central station to Taunusanlage station, built on the site of the old city walls near the Alte Oper and the Deutsche Bank Twin Towers.

After passing under the Main the tunnel divides: One branch runs in the direction of Sachsenhausen where it runs under the Sachsenhausen old town to Frankfurt Lokalbahnhof and then climbs a ramp to the embankment of the South Main railway to Frankfurt South station.

At the South station the S-Bahn connects with regional and main line services was built, trams and the U-Bahn.

The second section, which was completed in 1992, branches off to the east on the Sachsenhausen side after the passage under the Main towards Mühlberg.

Then the line comes to the surface prior for a few kilometres until the next station at Offenbach-Kaiserlei where the Offenbach City Tunnel begins.