The Bernese Oberland Railway (BOB) connects Interlaken Ost with Grindelwald and Lauterbrunnen. Two train compositions are usually coupled together to travel to Zweilütschinen, where they are separated. One train travels to Grindelwald, the other to Lauterbrunnen. All compositions can be coupled together for shuttle purposes. The locomotive is always positioned on the uphill end of the train. A control car with drivers cab is positioned on the downhill end to avoid any switching manoeuvres at terminus stations. The railway began operating 1890, and was electrified in 1914. Since the introduction of the 1999 timetable, a newly constructed section of dual track between Zweilütschinen and Wilderswil has allowed trains to pass without one having to wait on a side-line. This means that a half-hour timetable can be operated with only five train compositions. Since 2005, every composition has been equipped with a comfortable three-part low-floor unit as standard.
The idea of building a railway through the two Lütschinen Valleys arose in 1873. However, the Aarmühle council (later Interlaken council) rejected the first project, a resolution with which the decision makers in the neighbouring municipalities of Matten, Unterseen, Wilderswil and Bönigen were in agreement. Grindelwald was initially uninterested in a rail link while Lauterbrunnen was undecided. But then public opinion changed and the project began to receive wide support. The Bernese Oberland Railway (BOB) in Interlaken was founded on 2 November 1888. The narrow-gauge railway from Interlaken Ost to Grindelwald and Lauterbrunnen began operations on 1 July 1890.