The Buchloe–Lindau railway is a double-track, largely non-electrified main line in the German state of Bavaria. It runs through the Allgäu from Buchloe to Lindau in Lake Constance via Kaufbeuren and Kempten. Together with the connecting Munich–Buchloe railway it is known in German as the Bayerische Allgäubahn (Bavarian Allgäu railway). The Royal Bavarian State Railways (Königlich Bayerischen Staatseisenbahnen) put the line into operation between 1847 and 1854 as part of the Ludwig South-North Railway (Ludwig-Süd-Nord-Bahn). The Hergatz–Lindau section was electrified between 2018 and 2020 as part of the Munich–Lindau upgraded line project, which uses a shorter but largely single-track route via Memmingen. History The line from Buchloe to Lindau was built as part of the Ludwig South-North Railway from Hof via Augsburg and Kempten to Lindau. The first 20.3 kilometres from Buchloe to were opened to traffic on 1 September 1847. This was followed by the 42.52 km over the King Louis Bridge (König-Ludwig-Brücke, later replaced by the Upper Iller bridge—Obere Illerbrücke) to the former Kempten terminus on 1 April 1852. The 21.66 km to Immenstadt were added on 1 May 1853. Another 16.85 km section to Oberstaufen were inaugurated on 1 September 1853 and the next 49.8 km to the Lindau suburb of Aeschach on 12 October 1853. The last 1.8 km section from Aeschach via the Bodensee embankment to the Lindau Stadt (Lindau town) terminus on the island of Lindau finally went into operation on 1 March 1854. Duplication of the original single track was completed in 1907. Until the journey times between Munich and Lindau was reduced by around 30 minutes with the introduction of DB Class V 200 diesel locomotives in the mid-1960s, the line was operated with steam locomotives. The former Bavarian S 3/6 (later class 18) locomotives provided high-quality, international express train services here for many decades. They were still used for express services at the end of 1967. From 23 May 1954 to 31 May 1958, railway buses ran from Augsburg and Biessenhofen via Pforzen, continuing for a short time to run by rail to Roßhaupten, before reaching Füssen by road. The Bundesbahn Central Offices tested almost every diesel locomotive class was on the line because of its hilly profile. These included the one-off 232 001 (later class V 320 001), which was subsequently operated as Deutsche Bundesbahn's only six-axle diesel locomotive. From 1975, Deutsche Bundesbahn intended to electrify the route between Munich