In a memorandum of September 1911, the Bavarian government discarded all these options in favour of an extension of the Starnberg wing station and the construction of Holzkirchen wing station ("Holzkirchner Bahnhof"), partly serving the line to Holzkirchen. It was also planned to relocate all the local traffic to the wing stations. It was assumed from the outset that in the future a through station would be appropriate. Construction began in 1914, and continued through the First World War, but it was delayed. The wing stations finally opened on 30 April 1921. Local traffic was largely shifted to the wing stations. The station reached 36 tracks in its largest expansion since the Holzkirchen wing station included an additional ten tracks. The trains were controlled by nine electromechanical interlockings built from 1922 to 1929.