Berlin

The U-Bahn opened in 1902 and has 173 stations stretched across 9 lines with a total length of 91 miles.  The U-Bahn trains run every two to five minutes during the day and every ten minutes during the night and on sundays.  The lines are rarely late and show up almost exactly on the time posted.  The U-Bahn was constantly being expanded until the Berlin wall was constructed.  When the Berlin Wall went up, the system remained running, but most trains stayed on their side.  All East Berlin lines were not allowed to go through West Berlin, but West Berlin had two lines that could go through East Berlin.  When those two lines went through East Berlin, they didn't stop.  The system reopened after the Berlin Wall went down.  After 34 years of being seperated, the East and West Berlin lines opened together in October of 1995.  Today the U-Bahn carries 1,400,000 passangers daily and travels speeds from 19-45 mph. 
http://en.wikipedia.org/wiki/Berlin_U-Bahn
http://chrisabraham.com/wp-content/uploads/2010/04/berlin-map.gif

S-Bahn
The Stadtschnellbahn or S-Bahn meaning “Urban rapid railway” was started in 1924 when old steam railways were turned into electric railways. The S-Bahn kept expanding until WWII when parts of it had to be closed down due to war damage. During the Cold War, the S-Bahn became a place of tension and hostility for travelers in Berlin’s divided east and west sectors. The S-Bahn ran two separated lines (run by the west and the east) until 1994 when the separate companies merged into one as a subsidiary under the Deutsche Bahn.
The S-Bahn carries up to 1.3 million passengers every workday. It has 332 kilometers of railway in its network with 166 stations and 15 different lines. It is customer oriented and has 3000 employees whose work ranges from customer service centers to platform staff. The S-Bahn company is also involved with community organizations aimed towards children and young adults. The S-Bahn connects with other train systems at the Berlin Hauptbahnof that houses 15 platforms on two levels. This makes train switching much easier for passengers travelling through Berlin, Germany, and Europe. The trains provide eco-friendly commuter and leisure transportation.
http://www.s-bahn-berlin.de/englisch/service/company.html
http://www.s-bahn-berlin.de/englisch/arrival-and-departure/main-station.html