Complex sentence: After the 2011 state election, the SPD and the CDU formed a grand coalition decided under the coalition agreement to develop plans to extend the S-Bahn line "from Spandau station to the west to Falkensee".
Split into simpler sentences: After the 2011 state election, the SPD and the CDU formed a grand coalition. The coalition agreement included a commitment to develop plans to extend the S-Bahn line "from Spandau station to the west to Falkensee".