Østsjællandske Jernbaneselskab (ØSJS or Østbanen) was a Danish railway company. The company operated the lines Køge-Hårlev/Rødvig/Faxe Ladeplads (Østbanen) and began operations on 1 July 1879. Until 1 January 2009, Østbanen was part of Lokalbanen A/S and Hovedstadens Lokalbaner A/S, after which the line was merged with the other private lines in Region Zealand to Regionstog A/S and on 1 July 2015 the line was included together with the other lines under Regionsstog and Lokalbanen in Lokaltog.
The line is a fork line and consists of two lines: 110R (Køge-Fakse Ladeplads) and 210R (Køge-Rødvig). In 2019, stbanen uses new Lint 41 train sets from 2011, which replaced the 30-year-old Y-trains, also nicknamed "The Pig".
Before the upgrade from 80 km/h to 100 km/h, the Y-trains ran for many years coupled two by two from Køge to Hårlev, where they were separated, and the front set of trains continued to Fakse Ladeplads, while the back seen ran two Rødvig. On the journey back to Køge, the trains were connected again in Hårlev. Today, after the installation of the Lint 41 trainsets, there is a 15-minute service between Køge and Hårlev, while there is a 30-minute service between Hårlev and Hårlev, respectively. Fax Ladeplads and Rødvig. This means that every other train from Køge goes to Fakse Ladeplads and every other train goes to Rødvig.
In 1964, Østbanen's trains began to continue from Køge to Roskilde along the Statens track (Lille Syd), which meant that you could travel directly from Roskilde to Rødvig and Fakse Ladeplads. This extra run was carried out with the timetable change on 30 September 1990, and since then Østbanen has not offered a run on the tracks to Roskilde, which is instead reserved for the line Roskilde-Køge-Næstved. In 2014, the Ministry of Transport proposed offering the State's tracks between Roskilde and Køge to Regionsstog A/S, with which Østbanen per 2018 can again offer transport to Roskilde.