S7 is a line on the Berlin S-Bahn. It operates from Ahrensfelde to Potsdam over: the Wriezen Railway, completed on 1 May 1898 and electrified to Marzahn in 1976, to Mehrower Allee in 1980 and to Ahrensfelde in 1982, From Wikipedia
The closure, affecting major lines, will run from April 11 to April 22, with replacement buses and alternative routes available.