The line is long and has a
track gauge of . It is a
rack and
adhesion railway, using the
Strub rack system to overcome a height difference of . Except for the terminal stations, which are operated in adhesion mode, the line has a gradient varying from 11% to 22%. The line is operated by the which also manages the
Mont Blanc Tramway and many
ski lifts in the
Mont Blanc region. The first section of the line as far as Caillet opened in 1908 and the line was completed in 1909. The trains originally were drawn by steam locomotives built by
SLM who supplied six 2-4-2T locomotives between 1908 and 1923. By 1953 the line was electrified, using an
overhead line at 11 kV
AC and 50
Hz, and service is provided by six electric railcars and trailers and three diesel locomotives, all from SLM. Trains run at and take 20 minutes for the journey. A
cable car connects the station at Montenvers with the glacier which is tunnelled out at that point enabling tourists to walk inside the glacier. ==Incidents==