Berlin S-Bahn electrification completed

July 7, 1927 marked the completion of the Berlin S-Bahn's comprehensive electrification project using 750 V DC third rail. Deutsche Reichsbahn engineers converted steam-hauled suburban services to electric multiple units, dramatically increasing frequency and capacity on the iconic Ringbahn circle and east-west Stadtbahn. This innovation supported Berlin's rapid urban growth during the Weimar Republic and set global standards for metropolitan rail systems. The project involved over 200 km of track and helped popularize the distinctive red-and-cream ET class trains. Its lasting impact includes serving as the template for post-WWII S-Bahn networks across Germany and influencing subway designs worldwide.