During World War II there was a massive construction by the German Forces as part of creating Festung Norwegen, including large sections of the Nordland Line and the completion of the Sørland Line. After the war the main effort was to complete the Nordland Line (which reached Bodø in 1962) and completing the decision to electrify 50% of the network, a task not completed until 1970. This allowed the retirement of the steam locomotive, being replaced with electric engines like the El 11 and El 13 or the diesel powered Di 3. In 1966 Norway's only rapid transit, Oslo T-bane was opened, but in the same decade the Bergen tramway was closed. In the 1970s and 80s a lot of branch lines were also abandoned.