The railway bridge over the Norderelbe consists of two separate bridges: The first Norderelbbrücke (also known as the Old Elbe Bridge) was built in 1868–1872. The iron superstructures were expanded from two to four tracks between 1890 and 1893 and the portals were widened accordingly. From 1926 to 1927 the bridge girders were replaced by stronger new buildings. The design of the new bridge was based on the free port bridge that was just completed at the time. The bridge has four tracks for long-distance and regional traffic.
About five meters next to this bridge, a parallel bridge with two tracks for the Harburg S-Bahn was built between 1978 and 1980. The two bridges differ in shape and color: the main bridge is painted gray and the extension is green.
Freeport Bridge:
The Freihafenelbbrücke was built in order to create a structurally separate crossing of the Elbe for what was then the free port. Construction work began in 1914 and was discontinued in 1917 due to the war. It was not completed and opened until 1926.
Source: Wikipedia