The Meiringen-Innertkirchen Bahn (MIB) is a narrow gauge railway in Switzerland with a rail gauge of 1 m (3 ft 33⁄8 in). It covers a distance of 5 km from Meiringen to Innertkirchen. At the Meiringen end, it is connected to the Swiss Federal Railways' Brünigbahn, but the two lines are incompatible electrically and no through services are operated. Note: The technology of being able to run electric locomotives or EMU's under different voltages and frequencies and/or under AC or DC has existed for some time now, see Multisystem locomotives.
The line was originally built as a construction railway to support the building of hydroelectric dams in the Oberhasli and the Grimsel Pass. A company, Kraftwerke Oberhasli (KWO) was founded in 1923 to build and operate the railway; the line opened in 1926. Several Mallet-type steam locomotives were acquired from the Rhätische Bahn to operate the line. As well as construction traffic, the line also operated a limited passenger service for workers and their families. In 1931 a battery railcar was purchased, and a second in 1939.
In 1946 the line received a license to operate as a public passenger-carrying railway, and to this end the Mieringen-Innertkirchen Bahn company was founded to operate the line as a subsidiary of the owners, KWO.
When the license came up for renewal in 1976, it was decided to upgrade the line drastically. The heavy, four-wheel battery railcars were harsh on the track and trackbed, and were at the end of their economic life. The line was electrified, and electric streetcar-type railcars were purchased. Currently three railcars are used to provide the service. Up to 17 out-and-back services are provided daily. Freight traffic is run as demand warrants, largely as spare parts for the power stations which arrive from the Brünigbahn.
The line features one long (1502 m) tunnel, the Kirchettunnel, at approximately 2 km from Meiringen. The workshops are at the far end in Innertkirchen.