There was originally no link between Altona and Hamburg, so freight moving from one line to the other had to be reloaded several times, which was time-consuming and expensive.

Even as this construction work was underway a new agreement was signed on 12 December 1904 known as the Ohlsdorfer Vertrag (Ohlsdorf contract) providing for: Electrification was decided on by the Prussian State Railways as track operator, after it had already carried out extensive tests on the Schöneweide–Spindlersfeld line in Berlin, using overhead lines with 6.3 kV 25 Hz AC, the system which it selected for Hamburg.

The urban and suburban line to Ohlsdorf was put into operation on 5 December 1906; one day later the new Hamburg Hauptbahnhof was commissioned.

Even before this decision was made the Stadtbahn and suburban railways were designated as the S-Bahn in 1934, four years after the Berlin network was so named.

Similarly, it was decided to use bottom contact third rail, which had a clear advantage at points, as the third-rail power would not have to be interrupted.

Although the link line as the core of the S-Bahn had good passenger traffic, it only touches the city centre at its northern edge.

The entire Altona station building was demolished and subsequently rebuilt in a plain 1970s style.

On 11 December 2008, the underground S-Bahn line opened from Ohlsdorf to Hamburg Airport.