The Hamburg-Altona link line () is a railway line in Hamburg, Germany. It now connects the lines from the north and west of Hamburg and Altona station with Hamburg Hauptbahnhof and the lines to the south and east. It was initially designed as a freight line only but is it now one of the busiest lines in Germany. It includes the suburban tracks of the Hamburg Stadtbahn, originally the core of the Hamburg S-Bahn. History The first railway connection In 1842 the Hamburg-Bergedorf Railway Company opened a 16.5 km line from Hamburg to Bergedorf. In 1846 this line was extended to Berlin. Two years later, the Altona-Kiel Railway Company opened a line to Kiel. 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. A two-track link line was therefore built between the stations. The route of the line is affected strongly in the Hamburg area by the city's former walls. A pile bridge was originally constructed for crossing the Alster river, which was replaced in 1868 by a new bridge, the Lombardsbrücke. The railway was opened in two sections: 30 September 1865: Altona–Schulterblatt 16 July 1866: Schulterblatt–Klosterthor South of Klosterthor Station, there were provisional communication rail tracks in the streets to Berlin Station and from 1872 to Venlo Station. 30 years later, the line had already reached its limit and extra capacity had to be added. Adding capacity and extension of the line On 30 December 1898, Prussia, the city of Hamburg and the Lübeck-Büchen Railway Company agreed to the following elements of the link line: construction of a new central train station to replace the former terminal stations of the lines to Lübeck, Berlin and Hanover as well as the Klostertor station and link the converging routes, elevation of the line to eliminate all level crossings, including the construction of a separate northern pair of lines for suburban trains and extension of the connection line to Hasselbrook. This only applied to the suburban line, as the Lübeck–Hamburg line already existed for long-distance traffic. The widening of the Lombardsbrücke was completed in 1901 and 1902, including the addition of the suburban line. 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: extension of the