Since 1973, the RhB the Bernina Express takes as a separate train from Chur to Tirano. In the early years took place because of the different power systems between main line and Bernina railway locomotive changes necessary in Samedan. The Bernina Express from Chur to come here was divided. Train locomotive and the front part of the train continued on to St. Moritz. The principal feature was inherited from the dual power locomotive Gem 4 / 4. This led to the train in diesel traction Surovas and changed there to DC operation to Tirano.
The composition was then made of the still green, shortened unit cars of 2307-2314 and Series B
B 2451-2460 and the 1541-1546 AB. In the low traffic season often enough for a single Gem 4 / 4.
