Another training puzzle, this is a 123 box, a variation on the ABC box that was introduced at the German Logic Masters.
Also, I’ve posted a Doppelter Rundweg on the puzzle portal. That one is probably the hardest puzzle I’ve constructed to date.
Rules Put a number from 1 to 3 in each cell. The hints correspond exactly to connected groups of equal numbers within that row/column. A number clue stands for a group that consists of that number, or is that size, or both. A question mark clue stands for an arbitrary non-empty group.
There’s an example with the (German) instructions on the puzzle wiki.
Maybe Puzzles 
While definitely not easy this one and the Doppelter Rundweg felt both much easier than your Sackbahnhöfe for which I still haven’t found an approach. Very nice the first two and solvable completely logically. Not yet sure about the latter one ;).
Now I wonder if I made some bad deduction with the Sackbahnhöfe. It doesn’t feel particularly difficult to me.
Oh, it might help to solve it as a Sackbahnhöfe puzzle instead of Höhlenbahnhöfe. Seems as if the weekend left some marks…
Bei mir war es umgekehrt, und zwar um ein Vielfaches (zeitlich gesehen)…?