the time of the introduction of these lines, as the line to Holzkirchen via Deisenhofen still had the number S 2 (instead of the current S 3). These lines cross the Isar via Großhesselohe Bridge. In the Deutsche Bahn time table, the S-Bahn lines are numbered from 999.1 to 999.8 and 999.20; line A is numbered as 999.30. Frequency The basic interval of the Munich S-Bahn is one train every 20 minutes. On parts of some branches during peak hours there is a 10-minute frequency produced by added trains. A special case is the line to Erding, where on weekdays a mix of express trains from Erding and normal S-Bahn trains from Markt Schwaben runs in the morning peaks, producing a 10-minute frequency west of Munich East station. There are also occasional additional trains on the western section of the S4 and on the S1 between Freising and Munich during the peak hour, which do not continue past the Hauptbahnhof (not run through the trunk line tunnel). On some branches, one of three trains does not run to the terminus station at off-peak times, so that on these outer sections trains run at 20 or 40 minutes alternatively. The S8 is 24/7 (only to airport direction). (*) Terminus of extra services in peak. Up to here services in the peak run at 10-minute intervals. (+) Occasional additional services to create 10 minute frequency. Routes The S-Bahn partly operates on its own routes (one or two tracks), parts of it are double-track lines where S-Bahn operations are mixed with other traffic (passengers and freight), and in some cases more than two tracks are available. In the latter case one-or two tracks are set aside for the S-Bahn operations only and the two other tracks are used for the remaining traffic. In the following table, the route length is shown from Munich Hauptbahnhof or from Ostbahnhof (Munich East station) because it reflects the chainage officially applied to the lines. An exception is S27 where the chainage starts at Pasing. Former Lines / Station Renamings Here are some of the former train lines. Some of the stations are also renamed as well. /: Until the tunnel section on the Donnersbergerbrücke was opened on 31 May 1981, instead today's S7 and S10 to Hauptbahnhof (Holzkirchner wing station) without stopping at Donnersberger and Hackerbrücke. Instead of the later, Starnberg wing station to Munich Hauptbahnhof, the