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Special Romanian feature: old two-axle railcars coupled at the back of a loco with carriages train.

Is this railcars going together with train all trip? Or only some distance, and next they are separating, and going alone in other direction? I saw similar situation last year when I was in Timisoara. In the timetable at those time was only one train. I remember that in railcars were drivers, and the engines were working.

In this photo, the railcars are going, for the last part of their trip, together with train 3122 from Santana to Arad.
In the morning the railcars made the following trains :
P 3729 Arad - Santana - Chisineu Cris, and 3730 Chisineu Cris - Santana.