It begins the journey attached to one train, and arrives at its destination attached to another train.
[1][2] Through coaches save their transit passengers the need to change trains themselves.
[1] They also increase the number of direct links offered by the train operator(s).
[2] Most frequently in the form of sleeping or couchette cars, through coaches have commonly been used for long-distance journeys, especially in continental Europe, although they are much less common now than they were in the early 1970s.
[2] In 2010 and 2011, the Basel – Moscow sleeping car (2,856 km or 1,775 mi in 37 hours and 11 minutes) was attached successively to the following trains:[3][4]