The Dachau–Altomünster railway, also called the Bummerl, Bockerl or Ludwig Thoma Railway, is a railway in the German state of Bavaria. It is part of the Munich S-Bahn network and is integrated within the Münchner Verkehrs- und Tarifverbund as line S2. The branch line connects the town of Dachau on the Munich–Treuchtlingen railway with Altomünster. Markt Indersdorf is an important stop. Until its electrification in 2014, it was the only non-electrified line of the Munich S-Bahn and was designated as line A.

Ludwig Thoma was a German author, publisher and editor, who gained popularity through his partially exaggerated description of everyday Bavarian life.